Publikationsliste Dr. Nils Paust

Originalarbeiten in wissenschaftlichen Fachzeitschriften
Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften
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Originalarbeiten in wissenschaftlichen Fachzeitschriften

Jahre: 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007

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2023

Y.-K. Lai, Y.-T. Kao, J. Hess, S. Calabrese, F. von Stetten, N. Paust
Interfacing centrifugal microfluidics with linear-oriented 8-tube strips and multichannel pipettes for increased throughput of digital assays
2023 Lab on a Chip, Band: 23, Seiten: 2623 - 2632
F. Schlenker, P. Juelg, J. Lüddecke, N. Paust, R. Zengerle, T. Hutzenlaub
Nanobead handling on a centrifugal microfluidic LabDisk for automated extraction of cell-free circulating DNA with high recovery rates
2023 Analyst
B. Johannsen, D. Baumgartner, M. Karpíšek, D. Stejskal, N. Boillat-Blanco, J. Knüsli, M. Panning, N. Paust, R. Zengerle, K. Mitsakakis
Patient Stratification for Antibiotic Prescriptions Based on the Bound-Free Phase Detection Immunoassay of C-Reactive Protein in Serum Samples
2023 Biosensors, Band: 13, Seite: 1009

2022

B. Johannsen, D. Baumgartner, L. Karkossa, N. Paust, M. Karpíšek, N. Bostanci, R. Zengerle, K. Mitsakakis
ImmunoDisk - a fully automated bead-based immunoassay cartridge with all reagents pre-stored
2022 Biosensors, Band: 12, Nummer: 6, Seite: 413
S. Hin, N. Paust, M. Rombach, J. Lüddecke, M. Specht, R. Zengerle, K. Mitsakakis
Magnetophoresis in Centrifugal Microfluidics at Continuous Rotation for Nucleic Acid Extraction
2022 Micromachines, Band: 13, Seite: 2112

2021

A. Homann, L. Niebling, S. Zehnle, M. Beutler, L. Delamotte, M.C. Rothmund, D. Czurratis, K.-D. Beller, R. Zengerle, H. Hoffmann, N. Paust
A microfluidic cartridge for fast and accurate diagnosis of Mycobacterium tuberculosis infections on standard laboratory equipment
2021 Lab on a Chip, Band: 21, Nummer: 8, Seiten: 1540 - 1548
KurzfassungWe present a novel centrifugal microfluidic approach for fast and accurate tuberculosis (TB) diagnosis based on the use of standard laboratory equipment. The herein presented workflow can directly be integrated into laboratories with standard equipment and automates complex sample preparation. The system consists of a microfluidic cartridge, a laboratory centrifuge and a standard PCR cycler. The cartridge includes all required reagents and automates collection of bacteria on filter membranes, bacterial lysis, nucleic acid extraction and aliquoting of the DNA extract for PCR analysis. We show that storage of the reagents in aluminium-coated pouches is stable during accelerated storage and transport tests. When the limit of detection was assessed, we found that the cartridge-automated workflow consistently detected 10 CFU ml−1 of mycobacteria in spiked sputum samples. First tests with clinical samples showed a 100% specificity for non-TB specimens. In addition, Mycobacterium tuberculosis (MTB) was re-found in pre-characterized smear microscopy and culture positive sputum samples suggesting a high diagnostic sensitvity. In summary, the novel cartridge-automated workflow enables a flexible and sensitive TB diagnosis without the need to invest in specialized instrumentation.
J.-N. Klatt, T.J. Dinh, O. Schilling, R. Zengerle, F. Schmidt, T. Hutzenlaub, N. Paust
Automation of peptide desalting for proteomic liquid chromatography–tandem mass spectrometry by centrifugal microfluidics
2021 Lab on a Chip, Band: 21, Nummer: 21, Seite: 2255
KurzfassungFor large-scale analysis of complex protein mixtures, liquid chromatography – tandem mass spectrometry (LC-MS/MS) has been proven to be one of the most versatile tools due to its high sensitivity and ability to both identify and quantify thousands of proteins in a single measurement. Sample preparation typically comprises site-specific cleavage of proteins into peptides, followed by desalting and concomitant peptide enrichment, which is commonly performed by solid phase extraction. Desalting workflows may include multiple liquid handling steps and are thus error prone and labour intensive. To improve the reproducibility of sample preparation for low amounts of protein, we present a centrifugal microfluidic disk that automates all liquid handling steps required for peptide desalting by solid phase extraction (DesaltingDisk). Microfluidic implementation was enabled by a novel centrifugal microfluidic dosing on demand structure that enabled mapping multiple washing steps onto a microfluidic disk. Evaluation of the microfluidic disk was performed by LC-MS/MS analysis of tryptic HEK-293 eukaryotic cell peptide mixtures desalted either using the microfluidic disk or a manual workflow. A comparable number of peptides were identified in the disk and manual set with 19 775 and 20 212 identifications, respectively. For a core set of 10 444 peptides that could be quantified in all injections, intensity coefficients of variation were calculated based on label-free quantitation intensities. The disk set featured smaller variability with a median CV of 9.3% compared to the median CV of 12.6% for the manual approach. Intensity CVs on protein level were lowered from 5.8% to 4.2% when using the LabDisk. Interday reproducibility for both workflows was assessed by LC-SRM/MS analysis of samples that were spiked with 11 synthetic peptides of varying hydrophobicity. Except for the most hydrophilic and hydrophobic peptides, the average CV was lowered to 3.6% for the samples processed with the disk compared to 7.2% for the manual workflow. The presented centrifugal microfluidic DesaltingDisk demonstrates the potential to improve reproducibility in the sample preparation workflow for proteomic mass spectrometry, especially for application with limited amount of sample material.
J.-N. Klatt, T. Hutzenlaub, T. Subkowski, T. Müller, S. Hennig, R. Zengerle, N. Paust
Blocking Protein Adsorption in Microfluidic Chips by a Hydrophobin Coating
2021 ACS Appl. Polym. Mater., Band: 3, Nummer: 7, Seiten: 3278 - 3286
KurzfassungMicrofluidics allows the miniaturization of biochemical analyses. Small dimensions reduce sample and reagent consumption and enhance reaction rates. A downside is that high surface-to-volume ratios increase the unspecific binding of proteins to the substrate material. The resulting sample loss and reagent depletion decrease the sensitivity and specificity of protein-based assays, especially if low concentrations are analyzed. Here, we introduce the hydrophobin coating of microfluidic chips made of cyclic olefin copolymers (COC). The recombinant hydrophobin H*Protein B self-assembles into stable monolayers on hydrophobic surfaces, making them hydrophilic and thus reducing hydrophobic interactions between the chip surfaces and proteins. The substrate and sealing layers of the microfluidic chip were simply dip-coated and subsequently assembled by thermodiffusion bonding, which renders our coating procedure compatible with mass fabrication. Contact angle measurements and atomic force microscopy were used to evaluate the effect of high temperatures (107 °C) on COC substrates coated with H*Protein B. The efficiency of the protein-repellent coating was evaluated by depletion experiments with bovine serum albumin, human serum, and cerebrospinal fluid in microfluidic chips. Protein recovery was investigated down to protein concentrations of 0.3 μg/mL. Recoveries of 90% were observed with total protein amounts of 10 ng, even for microfluidic channels up to 835 mm in length and with a cross section of 80 μm × 230 μm in a COC 6013/8007 foil. For comparison, only 30 and 60% of the protein was recovered in uncoated microfluidic channels with lengths of 835 and 128 mm, respectively. The long-term stability of the hydrophobin-coated chips for 8 weeks was demonstrated.
F. Schlenker, E. Kipf, N. Borst, N. Paust, R. Zengerle, F. von Stetten, P. Juelg, T. Hutzenlaub
Centrifugal Microfluidic Integration of 4-Plex ddPCR Demonstrated by the Quantification of Cancer-Associated Point Mutations
2021 Processes, Band: 2021, Nummer: 9, Ergänzungsband: 97
KurzfassungWe present the centrifugal microfluidic implementation of a four-plex digital droplet polymerase chain reaction (ddPCR). The platform features 12 identical ddPCR units on a LabDisk cartridge, each capable of generating droplets with a diameter of 82.7 +/- 9 µm. By investigating different oil–surfactant concentrations, we identified a robust process for droplet generation and stabilization. We observed high droplet stability during thermocycling and endpoint fluorescence imaging, as is required for ddPCRs. Furthermore, we introduce an automated process for fourcolor fluorescence imaging using a commercial cell analysis microscope, including a customized software pipeline for ddPCR image evaluation. The applicability of ddPCRs is demonstrated by the quantification of three cancer-associated KRAS point mutations (G12D, G12V and G12A) in a diagnostically relevant wild type DNA background. The four-plex assay showed high sensitivity (3.5–35 mutant DNA copies in 15,000 wild type DNA copies) and linear performance (R2 = 0.99) across all targets in the LabDisk.
D. Kainz, B. Breiner, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Eliminating viscosity bias in lateral flow tests
2021 Microsystems & Nanoengineering, Band: 7, Seite: 72
S. Hin, B. Lopez-Jimena, M. Bakheit, V. Klein, S. Stack, C. Fall, A. Sall, K. Enan, M. Mustafa, V. Rusu, S. Goethel, N. Paust, R. Zengerle, L. Gillies, S. Frischmann, M. Weidmann, K. Mitsakakis
Fully automated point-of-care differential diagnosis of acute febrile illness
2021 PLoS Negl. Trop. Dis., Band: 15, Nummer: 2, Seite: e0009177
KurzfassungIn this work, a platform was developed and tested to allow to detect a variety of candidate viral, bacterial and parasitic pathogens, for acute fever of unknown origin. The platform is based on a centrifugal microfluidic cartridge, the LabDisk (“FeverDisk” for the specific application), which integrates all necessary reagents for sample-to-answer analysis and is processed by a compact, point-of-care compatible device...
M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. Homann, F. von Stetten, R. Zengerle, N. Paust
High Dynamic Range Digital Assay Enabled by Dual-Volume Centrifugal Step Emulsification
2021 Analytical Chemistry, Band: 93, Nummer: 5, Seiten: 2854 - 2860
KurzfassungWe implement dual-volume centrifugal step emulsification on a single chip to extend the dynamic range of digital assays. Compared to published single-volume approaches, the range between the lower detection limit (LDL) and the upper limit of quantification (ULQ) increases by two orders of magnitude. In comparison to existing multivolume approaches, the dual-volume centrifugal step emulsification requires neither complex manufacturing nor specialized equipment. Sample metering into two subvolumes, droplet generation, and alignment of the droplets in two separate monolayers are performed automatically by microfluidic design. Digital quantification is demonstrated by exemplary droplet digital loop-mediated isothermal amplification (ddLAMP). Within 5 min, the reaction mix is split into subvolumes of 10.5 and 2.5 μL, and 2,5k and 176k droplets are generated with diameters of 31.6 ± 1.4 and 213.9 ± 7.5 μm, respectively. After 30 min of incubation, quantification over 5 log steps is demonstrated with a linearity of R2 ≥ 0.992.
J.-N. Klatt, I. Schwarz, T. Hutzenlaub, R. Zengerle, F. Schwemmer, D. Kosse, J. Vincent, M. Scaer, K. Franaszczuk, D. Wadsworth, N. Paust
Miniaturization, Parallelization, and Automation of Endotoxin Detection by Centrifugal Microfluidics
2021 Analytical Chemistry, Band: 93, Nummer: 24
KurzfassungWe demonstrate microfluidic automation and parallelization of Limulus amebocyte lysate (LAL)-based bacterial endotoxin testing using centrifugal microfluidics. LAL is the standard reagent to test for endotoxin contaminations in injectable pharmaceuticals. The main features of the introduced system are more than 90% reduction of LAL consumption, from 100 μL/reaction to 9.6 μL/reaction, automated liquid handling to reduce opportunities for contamination and manual handling errors, and microfluidic parallelization by integrating 104 reactions into a single centrifugal microplate. In a single Eclipse microplate, 21 samples and their positive product controls are tested in duplicate. In addition, a standard curve with up to five points is generated, resulting in a total of 104 reactions. Test samples with a defined concentration of 0.5 endotoxin units per milliliter were tested, resulting in a coefficient of variation below 0.75%. A key feature for achieving a small coefficient of variation is ensuring the same path length along the microfluidic channels to the final reaction chambers for each sample and the reagent, so that any unspecific adsorption to the polymer surfaces does not affect the accuracy and precision. Analysis of a sample containing naturally occurring endotoxin with the developed microfluidic microplate yielded comparable results to the conventional testing method. A test with eight commercially available pharmaceuticals was found to pass all requirements for bacterial endotoxin testing as specified in the United States Pharmacopeia. The automated endotoxin testing system reveals specific advantages of centrifugal microfluidics for analytical biochemistry applications. Small liquid volumes are handled (metered, mixed, and aliquoted) in a very precise, highly integrated, and highly parallel manner within mass-fabricated microplates.
B. Johannsen, M. Karpíšek, D. Baumgartner, V. Klein, N. Bostanci, N. Paust, S. M. Früh, R. Zengerle, K. Mitsakakis
One-step, wash-free, bead-based immunoassay employing bound-free phase detection
2021 Analytica Chimica Acta, Band: 1153, Seite: 338280
KurzfassungWe present a simple and fast one-step heterogeneous immunoassay, with performance characteristics that can enable easy and versatile adaptation to miniaturized, automated point-of-care systems. This novel analytical method uses magnetic and fluorescent beads as capture and detection agents respectively. Its main feature is the measurement of the fluorescent signal in the bound-free phase for (semi-)quantitative detection of analytes. Thus, no washing is required and the workflow consists only of sample and reagent supply, incubation, separation and detection. The immunoassay concept is demonstrated with C-reactive protein (CRP), a systemic inflammation marker. CRP in only 5 μL of undiluted serum was measured in the range 20-140 mg L-1 (includes clinically relevant cut-off values). The limit of detection (LOD) was 22.1 ± 6.3 mg L-1 (incubation 15 min). A CRP certified reference material was measured on five different days. Intra- and inter-assay coefficients of variation were 4.6 % ± 1.9 % and 5.6 % respectively. To demonstrate the compatibility of the assay concept with additional matrices and concentration ranges, three oral inflammation markers, namely matrix metalloproteinases 8 and 9 (MMP-8, MMP-9) and tissue inhibitor of metalloproteinases 1 (TIMP-1), were measured in saliva in the ranges 0.47-30 ng mL-1 for MMP-8 and MMP-9, and 0.69-44 ng mL-1 for TIMP-1. LODs were 0.24 ng mL-1, 0.38 ng mL-1 and 0.39 ng mL-1 respectively (incubation 20 min). Multiplexing capacity of the assay concept was also shown with these markers. The demonstrated excellent reproducibility of the results, combined with the versatility and low complexity of the introduced immunoassay concept, make it an attractive candidate for applied analytical chemistry and automated point-of-care testing.
D. Baumgartner, B. Johannsen, M. Specht, J. Lüddecke, M. Rombach, S. Hin, N. Paust, F. von Stetten, R. Zengerle, C. Herz, J. R. Peham, P. N. Paqué, T. Attin, J. S. Jenzer, P. Körner, P. R. Schmidlin, T. Thurnheer, F. J. Wegehaupt, W. E. Kaman, A. Stubbs, J. P. Hays, V. Rusu, A. Michie, T. Binsl, D. Stejskal, M. Karpíšek, K. Bao, N. Bostanci, G. N. Belibasakis, K. Mitsakakis
OralDisk: A Chair-Side Compatible Molecular Platform Using Whole Saliva for Monitoring Oral Health at the Dental Practice
2021 Biosensors, Band: 11, Nummer: 11, Seite: 423
L. Becherer, J. F. Hess, S. Frischmann, M. Bakheit, H. Nitschko, S. Stinco, F. Zitz, H. Hofer, G. Porro, F. Hausladen, K. Stock, D. Drossart, H. Wurm, H. Kuhn, D. Huber, T. Hutzenlaub, N. Paust, M. Keller, O. Strohmeier, S. Wadle, N. Borst, R. Zengerle, F. von Stetten
Point-of-Care System for HTLV-1 Proviral Load Quantification by Digital Mediator Displacement LAMP
2021 Micromachines, Band: 12, Nummer: 2, Seite: 159
KurzfassungThis paper presents a universal point-of-care system for fully automated quantification of human T-cell lymphotropic virus type 1 (HTLV-1) proviral load, including genomic RNA, based on digital reverse RNA transcription and c-DNA amplification by MD LAMP (mediator displacement loop-mediated isothermal amplification). A disposable microfluidic LabDisk with pre-stored reagents performs automated nucleic acid extraction, reaction setup, emulsification, reverse transcription, digital DNA amplification, and quantitative fluorogenic endpoint detection with universal reporter molecules. Automated nucleic acid extraction from a suspension of HTLV-1-infected CD4+ Tlymphocytes (MT-2 cells) yielded 8 +/- 7 viral nucleic acid copies per MT-2 cell, very similar to the manual reference extraction (7 +/- 2 nucleic acid copies). Fully automated sample processing from whole blood spiked with MT-2 cells showed a comparable result of 7 +/- 3 copies per MT-2 cell after a run time of two hours and 10 min.
P. Juelg, E. Kipf, M. Specht, M. Fillies, C. Eckert, N. Paust, R. Zengerle, M. Lehnert, T. Hutzenlaub
The MRD disk: automated minimal residual disease monitoring by highly sensitive centrifugal microfluidic multiplex qPCR
2021 Lab Chip, Band: 21, Seiten: 558 - 570
KurzfassungWe present a proof-of-principle study on automated, highly sensitive and multiplexed qPCR quantification by centrifugal microfluidics. The MRD disk can be used for standardisation of repetitive, longitudinal assays with high requirements on reproducibility and sensitivity, such as cancer monitoring. In contrast to high-throughput qPCR automation by bulky and expensive robotic workstations we employ a small centrifugal microfluidic instrument, addressing the need of low- to mid-throughput applications. As a potential application we demonstrate automated minimum residual disease (MRD) monitoring of prognostic markers in patients with acute lymphoblastic leukaemia (ALL). The disk-workflow covers all aspects of clinical gold standard MRD quantification: generation of standard curves, specificity controls, no template controls and quantification of the ALL patient sample. We integrated a highly sensitive, colorimetric 2-plex analysis of MRD targets, as well as a 2-plex analysis of reference genes, both in parallel and in a single LabDisk cartridge. For this purpose, a systematic procedure for crosstalk- and signal-to-noise-optimisation is introduced, providing a guideline for efficient multiplex readout inside microfluidic platforms. The qPCR standard curves (n = 12/12) generated on-disk reach clinically required linearity (R2 = 98.1% to R2 = 99.8%). In three consecutive MRD disk runs with an ALL patient sample containing the two representative MRD targets VH3D3D5JH3 and VkIkde, we observe high accordance between the on-disk quantifications (48 ± 6 copies/reaction and 69 ± 6 copies/reaction) and the expected concentrations (57 copies/reaction for both targets). In comparison to the clinical gold standard of manually pipetted, singleplex assays, the MRD disk yields comparable limit of quantification (1 × 10−4) in n = 6/6 analyses (vs. n = 4/4 in gold standard) and a limit of detection (1 × 10−5) in n = 6/6 analysis (vs. n = 2/4 in gold standard). The automation reduces the risk of manual liquid handling errors, making the MRD disk an attractive solution to assure reproducibility in moderate-throughput, longitudinal gene quantification applications.

2020

J. F. Hess, M. Kotrová, S. Calabrese, N. Darzentas, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. Paust
Automation of amplicon-based library preparation for next generation sequencing by centrifugal microfluidics
2020 Anal Chem, Band: 92, Nummer: 19, Seiten: 12833 - 12841
KurzfassungNext generation sequencing has become a mainstream method in bioanalysis. Improvements in sequencing and bioinformatics turned the complex and cumbersome library preparation to the bottle neck in terms of reproducibility and costs in the complete NGS workflow. Here, we introduce an automated library preparation approach based on a generic centrifugal microfluidic car-tridge. Multiplex polymerase chain reaction amplification and subsequent clean-up were processed with all reagents pre-stored on disk, including cell line-based DNA as quality control. Exchange of pre-stored reagents allows to apply the cartridge to different target genes. Sequencing of automatically prepared libraries from T-cell receptor and immunoglobulin gene rearrangements in context of lymphoproliferative disorders demonstrated excellent clean-up performance between 91.9% and 99.9% of target DNA reads and successful amplification of all target regions by up to 15 forward combined with four reverse primers. The fully auto-mated library preparation by centrifugal microfluidics thus offers attractive automation options in diagnostic settings.
M. Schulz, S. Calabrese, F. Hausladen, H. Wurm, D. Drossart, K. Stock, A. M. Sobieraj, F. Eichenseher, M. J. Loessner, M. Schmelcher, A. Gerhardts, U. Goetz, M. Handel, A. Serr, G. Haecker, J. Li, M. Specht, P. Koch, M. Meyer, P. Tepper, R. Rother, M. Jehle, S. Wadle, R. Zengerle, F. von Stetten, N. Paust, N. Borst
Point-of-care testing system for digital single cell detection of MRSA directly from nasal swabs
2020 Lab Chip, Band: 20, Seiten: 2549 - 2561
KurzfassungWe present an automated point-of-care testing (POCT) system for rapid detection of species- and resistance markers in methicillin-resistant Staphylococcus aureus (MRSA) at the level of single cells, directly from nasal swab samples. Our novel system allows clear differentiation between MRSA, methicillin-sensitive S. aureus (MSSA) and methicillin-resistant coagulase-negative staphylococci (MR-CoNS), which is not the case for currently used real-time quantitative PCR based systems. On top, the novel approach outcompetes the culture-based methods in terms of its short time-to-result (1 h vs. up to 60 h) and reduces manual labor. The walk-away test is fully automated on the centrifugal microfluidic LabDisk platform. The LabDisk cartridge comprises the unit operations swab-uptake, reagent pre-storage, distribution of the sample into 20 000 droplets, specific enzymatic lysis of Staphylococcus spp. and recombinase polymerase amplification (RPA) of species (vicK) – and resistance (mecA) -markers. LabDisk actuation, incubation and multi-channel fluorescence detection is demonstrated with a clinical isolate and spiked nasal swab samples down to a limit of detection (LOD) of 3 ± 0.3 CFU μl−1 for MRSA. The novel approach of the digital single cell detection is suggested to improve hospital admission screening, timely decision making, and goal-oriented antibiotic therapy. The implementation of a higher degree of multiplexing is required to translate the results into clinical practice.
M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, L. Roux, T. Sutcliffe, J. Peham, C. Herz, M. Panning, O. Donoso Mantke, K. Mitsakakis
RespiDisk: a point-of-care platform for fully automated detection of respiratory tract infection pathogens in clinical samples
2020 Analyst, Band: 145, Seiten: 7040 - 7047
KurzfassungWe present the RespiDisk enabling the fully automated and multiplex point-of-care (POC) detection of (currently) up to 19 respiratory tract infection (RTI) pathogens from a single sample based on reverse transcriptase polymerase chain reaction (RT-PCR). RespiDisk comprises a RTI-specific implementation of the centrifugal microfluidic LabDisk platform and combines new and existing advanced unit operations for liquid control, thereby automating all assay steps only by a spinning frequency and temperature protocol in combination with the use of a permanent magnet for in situ bead handing. The capabilities of the system were demonstrated with 36 tested quality samples mimicking clinical conditions (clinical and/or cultured material suspended in transport medium or synthetic bronchoalveolar lavage (BAL)) from past external quality assessment (EQA) panels covering 13 of the 19 integrated RTI detection assays. In total, 36 samples × 19 assays/sample resulting in 684 assays were performed with the RespiDisk, and its analytical performance was in full agreement with the routine clinical workflow serving as reference. A strong feature of the platform is its universality since its components allow the simultaneous detection of a broad panel of bacteria and viruses in a single run, thereby enabling the differentiation between antibiotic-treatable diseases. Furthermore, the full integration of all necessary biochemical components enables a reduction of the hands-on time from manual to automated sample-to-answer analysis to about 5 min. The study was performed on an air-heated LabDisk Player instrument with a time-to-result of 200 min.
J.-N. Klatt, M. Depke, N. Goswami, N. Paust, R. Zengerle, F. Schmidt, T. Hutzenlaub
Tryptic digestion of human serum for proteomic mass spectrometry automated by centrifugal microfluidics
2020 Lab Chip, Band: 20, Seite: 2937
KurzfassungMass spectrometry has become an important analytical tool for protein research studies to identify, characterise and quantify proteins with unmatched sensitivity in a highly parallel manner. When transferred into clinical routine, the cumbersome and error-prone sample preparation workflows present a major bottleneck. In this work, we demonstrate tryptic digestion of human serum that is fully automated by centrifugal microfluidics. The automated workflow comprises denaturation, digestion and acidification. The input sample volume is 1.3 μl only. A triplicate of human serum was digested with the developed microfluidic chip as well as with a manual reference workflow on three consecutive days to assess the performance of our system. After desalting and liquid chromatography tandem mass spectrometry, a total of 604 proteins were identified in the samples digested with the microfluidic chip and 602 proteins with the reference workflow. Protein quantitation was performed using the Hi3 method, yielding a 7.6% lower median intensity CV for automatically digested samples compared to samples digested with the reference workflow. Additionally, 17% more proteins were quantitated with less than 30% CV in the samples from the microfluidic chip, compared to the manual control samples. This improvement can be attributed to the accurate liquid metering with all volume CVs below 1.5% on the microfluidic chip. The presented automation solution is attractive for laboratories in need of robust automation of sample preparation from small volumes as well as for labs with a low or medium throughput that does not allow for large investments in robotic systems.
S. Hin, D. Baumgartner, M. Specht, J. Lüddecke, E. M. Arjmand, B. Johannsen, L. Schiedel, M. Rombach, N. Paust, F. von Stetten, R. Zengerle, N. Wipf, P. Müller, K. Mavridis, J. Vontas, K. Mitsakakis, * Indicates equally contributing authors
VectorDisk: A Microfluidic Platform Integrating Diagnostic Markers for Evidence-Based Mosquito Control
2020 Processes, Band: 8, Nummer: 12, Seite: 1677
KurzfassungEffective mosquito monitoring relies on the accurate identification and characterization of the target population. Since this process requires specialist knowledge and equipment that is not widely available, automated field-deployable systems are highly desirable. We present a centrifugal microfluidic cartridge, the VectorDisk, which integrates TaqMan PCR assays in two feasibility studies, aiming to assess multiplexing capability, specificity, and reproducibility in detecting disk-integrated vector-related assays. In the first study, pools of 10 mosquitoes were used as samples. We tested 18 disks with 27 DNA and RNA assays each, using a combination of multiple microfluidic chambers and detection wavelengths (geometric and color multiplexing) to identify mosquito and malaria parasite species as well as insecticide resistance mechanisms. In the second study, purified nucleic acids served as samples to test arboviral and malaria infective mosquito assays. Nine disks were tested with 14 assays each. No false positive results were detected on any of the disks. The coeffcient of variation in reproducibility tests was <10%. The modular nature of the platform, the easy adaptation of the primer/probe panels, the cold chain independence, the rapid (2–3 h) analysis, and the assay multiplexing capacity are key features, rendering the VectorDisk a potential candidate for automated vector analysis.
M. Schulz, S. Probst, S. Calabrese, A. Homann, N. Borst, M. Weiss, F. von Stetten, R. Zengerle, N. Paust
Versatile Tool for Droplet Generation in Standard Reaction Tubes by Centrifugal Step Emulsification
2020 Molecules, Band: 25, Nummer: 8, Seite: 1914
KurzfassungWe present a versatile tool for the generation of monodisperse water-in-fluorinated-oil droplets in standard reaction tubes by centrifugal step emulsification. The microfluidic cartridge is designed as an insert into a standard 2 mL reaction tube and can be processed in standard laboratory centrifuges. It allows for droplet generation and subsequent transfer for any downstream analysis or further use, does not need any specialized device, and manufacturing is simple because it consists of two parts only: A structured substrate and a sealing foil. The design of the structured substrate is compatible to injection molding to allow manufacturing at large scale. Droplets are generated in fluorinated oil and collected in the reaction tube for subsequent analysis. For sample sizes up to 100 µL with a viscosity range of 1 mPa·s–4 mPa·s, we demonstrate stable droplet generation and transfer of more than 6 × 105 monodisperse droplets (droplet diameter 66 µm ± 3 µm, CV ≤ 4%) in less than 10 min. With two application examples, a digital droplet polymerase chain reaction (ddPCR) and digital droplet loop mediated isothermal amplification (ddLAMP), we demonstrate the compatibility of the droplet production for two main amplification techniques. Both applications show a high degree of linearity (ddPCR: R2 ≥ 0.994; ddLAMP: R2 ≥ 0.998), which demonstrates that the cartridge and the droplet generation method do not compromise assay performance.

2019

B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S. M. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. Mitsakakis
Automated Pre-Analytic Processing of Whole Saliva Using Magnet-Beating for Point-of-Care Protein Biomarker Analysis
2019 Micromachines, Band: 10, Nummer: 12, Seite: 833
KurzfassungSaliva offers many advantages for point-of-care (PoC) diagnostic applications due to non-invasive, easy, and cost-effective methods of collection. However, the complex matrix with its non-Newtonian behavior and high viscosity poses handling challenges. Several tedious and long pre-analytic steps, incompatible with PoC use, are required to liquefy and homogenize saliva samples before protein analysis can be performed. We apply magnet-beating to reduce hands-on time and to simplify sample preparation. A magnet in a chamber containing the whole saliva is actuated inside a centrifugal microfluidic cartridge by the interplay of centrifugal and magnetic forces. Rigorous mixing, which homogenizes the saliva sample, is then initiated. Consequently, fewer manual steps are required to introduce the whole saliva into the cartridge. After 4 min of magnet-beating, the processed sample can be used for protein analysis. The viscosity of whole saliva has been reduced from 10.4 to 2.3 mPa s. Immunoassay results after magnet-beating for three salivary periodontal markers (MMP-8, MMP-9, TIMP-1) showed a linear correlation with a slope of 0.99 when compared to results of reference method treated samples. Conclusively, magnet-beating has been shown to be a suitable method for the pre-analytic processing of whole saliva for fully automated PoC protein analysis.
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, M. Keller, T. Hutzenlaub, F. von Stetten, R. Zengerle, N. Paust
Automated serial dilutions for high-dynamic-range assays enabled by fill-level-coupled valving in centrifugal microfluidics
2019 Lab Chip, Band: 19, Seiten: 2205 - 2219
KurzfassungWe introduce a new concept for centrifugal microfluidics that enables fully automated serial dilution generation without any additional means besides temperature control. Key feature is time-independent, serial valving of mixing chambers by fill-level-coupled temperature change rate (FLC-TCR) actuated valving. The automated dilution is realized under continuous rotation which enables reliable control of wetting liquids without the need of any additional fabrication steps such as hydrophobic coatings. All fluidic features are implemented in a monolithic fashion and disks are manufactured by foil thermoforming for scalable manufacturing. The new valving concept is demonstrated to reliably prevent valving if the diluted sample is not added to the mixing chamber (n = 30) and ensures valving if the dilution stage is completed (n = 15). Accuracy and precision of the automated serial dilution are verified by on-disk generation of qPCR standard curve dilutions and compared with manually generated reference dilutions. In a first step, the 5-log-stages standard curves are evaluated in a commercial qPCR thermocycler revealing a linearity of R² ≥ 99.92 % for the proposed LabDisk method vs. R² ≥ 99.67 % in manual reference dilutions. In a second step, the disk automated serial dilution is combined with on-disk qPCR thermocycling and readout, both inside a LabDisk Player. A 4-log-stages linearity of R² ≥ 99.81 % and a sensitivity of one leukemia associated ETV6-RUNX1 mutant DNA copy in a background of 100,000 wild-type DNA copies is achieved.
M. Schulz, F. von Stetten, R. Zengerle, N. Paust
Centrifugal Step Emulsification: How Buoyancy Enables High Generation Rates of Monodisperse Droplets
2019 Langmuir : the ACS Journal of Surfaces and Colloids, Band: 35, Nummer: 30, Seiten: 9809 - 9815
KurzfassungWe demonstrate that buoyancy in centrifugal step emulsification enables substantially higher generation rates of monodisperse droplets compared to pressure driven set-ups. Step emulsification in general can produce droplets in comparatively simple systems (only one moving liquid) with a low CV of <5% in droplet diameter and with a minimum dead volume. If operated below a critical capillary number, the droplet diameter is defined by geometry and surface forces only. Above that critical capillary number, however, jetting occurs, leading to an increased droplet diameter and CV. Consequently, generation rates of monodisperse droplets are limited in pressure-driven systems. In this paper, we show that centrifugal step emulsification can overcome this limitation by applying sufficient buoyancy to the system. The buoyancy, induced by the centrifugal field and a density difference of the continuous and disperse phase, supports droplet necking by pulling the forming droplet away from the nozzle. The influence of buoyancy is studied using specific microfluidic designs that allow for supplying different buoyancies to the same droplet generation rates. For a droplet diameter of 100 μm, droplet generation at rates above 2.8k droplets per second and nozzle were reached, which is an increase of more than a factor of 8 in comparison to pressure-driven systems.
D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Flow control for lateral flow strips with centrifugal microfluidics
2019 Lab Chip, Seiten: 2718 - 2727
KurzfassungLateral flow strips (LFSs) are widely used for clinical diagnostics. The restricted flow control of the current designs is one challenge to the development of quantitative and highly sensitive LFSs. Here, we present a flow control for LFSs using centrifugal microfluidics. In contrast to previously presented implementations of lateral flow membranes into centrifugal microfluidic cartridges, we direct the flow radially outwards through the membrane. We control the flow using only the centrifugal force, thus it is independent of membrane wetting properties and permeability. The flow rate can be decreased and increased, enabling control of incubation times for a wide variety of samples. We deduced a formula as a guideline for the integration of chromatographic membranes into centrifugal microfluidic disks to ensure that all the sample liquid flows through the membrane, hence safely avoiding bypass flow around the membrane. We verified the calculated operation conditions using different membranes, different flow rates, and different sample viscosities.

2018

S. Hin, N. Paust, M. Keller, M. Rombach, O. Strohmeier, R. Zengerle, K. Mitsakakis
Temperature change rate actuated bubble mixing for homogeneous rehydration of dry pre-stored reagents in centrifugal microfluidics
2018 Lab Chip, Band: 18, Seiten: 362 - 370
KurzfassungIn centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided. These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter with respect to pressure changes. Fast temperature increase causes rapid pressure increase in downstream structures pushing the liquid from downstream channels into the mixing chamber. As air further penetrates into the mixing chamber, bubbles form, ascend due to buoyancy and mix the liquid. Slow temperature/ pressure changes equilibrate through the high fluidic resistance air vent enabling sequential heating/cooling cycles to repeat the mixing process. After mixing, a complete transfer of the reaction volume into the downstream fluidic structure is possible by a rapid cooling step triggering TCR actuated valving. The new mixing concept is applied to rehydrate reagents for loop-mediated isothermal amplification (LAMP). After mixing, the reaction mix is aliquoted into several reaction chambers for geometric multiplexing. As a measure for mixing efficiency, the mean coefficient of variation (C —— V, n = 4 LabDisks) of the time to positivity (tp) of the LAMP reactions (n = 11 replicates per LabDisk) is taken. The C —— V of the tp is reduced from 18.5% (when using standard shake mode mixing) to 3.3% (when applying TCR actuated bubble mixing). The bubble mixer has been implemented in a monolithic fashion without the need for any additional actuation besides rotation and temperature control, which are needed anyhow for the assay workflow.

2017

N. Borst, F. Schuler, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, M. Trotter, A. B. Rodríguez-Martínez, N. Paust, R. Zengerle, F. von Stetten
A technology platform for digital nucleic acid diagnostics at the point of care
2017 Laboratoriumsmedizin, Band: 41, Nummer: 5
KurzfassungThe combination of digital amplification and centrifugal microfluidics can enable quantitative and fast diagnostics at the point of care (PoC). The new unit operation of centrifugal step emulsification allows high throughput droplet generation. Different methods for digital nucleic acid analysis, including PCR, recombinase polymerase amplification (RPA) and loop mediated isothermal amplification (LAMP), have already been demonstrated. Our novel approach of integrated sample-to-answer analysis is introduced, and examples for the detection of HIV and single cell analysis of antibiotic resistant bacteria are presented. Next to these LabDisk based systems, a microfluidic cartridge termed DropChip allows for digital amplification using only commercially available laboratory devices.
Y. Zhao, G. Czilwik, V. Klein, K. Mitsakakis, R. Zengerle, N. Paust
C-reactive protein and Interleukin 6 microfluidic immunoassays with on-chip pre-stored reagents and centrifugo-pneumatic liquid control
2017 Lab Chip, Band: 17, Nummer: 9, Seiten: 1666 - 1677
KurzfassungWe present a fully automated centrifugal microfluidic method for particle based protein immunoassays. Stick-pack technology is employed for pre-storage and release of liquid reagents. Quantitative layout of centrifugo-pneumatic particle handling, including timed valving, switching and pumping is assisted by network simulations. The automation is exclusively controlled by the spinning frequency and does not require any additional means. New centrifugal microfluidic process chains are developed in order to sequentially supply wash buffer based on frequency dependent stick-pack opening and pneumatic pumping to perform two washing steps from one stored wash buffer; pre-store and re-suspend functionalized microparticles on disk; and switch between the path of the waste fluid and the path of the substrate reaction product with 100% efficiency. The automated immunoassay concept comprises on demand ligand binding, two washing steps, substrate reaction, timed separation of the reaction products, and termination of the substrate reaction. We demonstrated separation of particles from three different liquids with particle loss below 4 % and residual liquid remaining within particles below 3 %. The automated immunoassay concept was demonstrated by means of detecting Creactive protein (CRP) in the range of 1 - 81 ng ml-1 and Interleukin 6 (IL-6) in the range of 64 - 13500 pg ml-1. The limit of detection and quantification were 1.0 ng ml-1 and 2.1 ng ml-1 for CRP; 64 pg ml-1 and 205 pg ml-1 for IL-6, respectively.
A. Fallisch, L. Schellhase, J. Fresko, M. Zechmeister, M. Zedda, J. Ohlmann, L. Zielke, N. Paust, T. Smolinka
Investigation on PEM water electrolysis cell design and components for a HyCon solar hydrogen generator
2017 Int J Hydrogen Energ, Band: 42, Seiten: 13544 - 13553
KurzfassungHydrogen as a secondary energy carrier promises a large potential as a long term storage for fluctuating renewable energies. In this sense a highly efficient solar hydrogen generation is of great interest especially in southern countries having high solar irradiation. The patented Hydrogen Concentrator (HyCon) concept yields high efficiencies combining multi-junction solar cells with proton exchange (PEM) membrane water electrolysis. In this work, a special PEM electrolysis cell for the HyCon concept was developed and investigated. It is shown that the purpose-made PEM cell shows a high performance using a titanium hybrid fiber sinter function both as a porous transport layer and flow field. The electrolysis cell shows a high performance with 1.83 V at 1 A/cm2 and 24 °C working under natural convection with a commercially available catalyst coated membrane. A theoretical examination predicts a total efficiency for the HyCon module from sunlight to hydrogen of approximately 19.5% according to the higher heating value.
S. Zehnle, M. Rombach, R. Zengerle, F. von Stetten, N. Paust
Network simulation-based optimization of centrifugo-pneumatic blood plasma separation
2017 Biomicrofluidics, Band: 11, Seite: 024114
KurzfassungAutomated and robust separation of 14 ll of plasma from 40 ll of whole blood at a purity of 99.81%60.11% within 43 s is demonstrated for the hematocrit range of 20%–60% in a centrifugal microfluidic polymer disk. At high rotational frequency, red blood cells (RBCs) within whole blood are concentrated in a radial outer RBC collection chamber. Simultaneously, plasma is concentrated in a radial inner pneumatic chamber, where a defined air volume is enclosed and compressed. Subsequent reduction of the rotational frequency to not lower than 25 Hz enables rapid transfer of supernatant plasma into a plasma collection chamber, with highly suppressed resuspension of red blood cells. Disk design and the rotational protocol are optimized to make the process fast, robust, and insusceptible for undesired cell resuspension. Numerical network simulation with lumped model elements is used to predict and optimize the fluidic characteristics. Lysis of the remaining red blood cells in the purified plasma, followed by measurement of the hemoglobin concentration, was used to determine plasma purity. Due to the pneumatic actuation, no surface treatment of the fluidic cartridge or any additional external means are required, offering the possibility for low-cost mass fabrication technologies, such as injection molding or thermoforming.
M. Keller, G. Czilwik, J. Schott, I. Schwarz, K. Dormanns, F. von Stetten, R. Zengerle, N. Paust
Robust temperature change rate actuated valving and switching for highly integrated centrifugal microfluidics
2017 Lab Chip, Band: 17, Seiten: 864 - 875
KurzfassungWe present new unit operations for valving and switching in centrifugal microfluidics that are actuated by a temperature change rate (TCR) and controlled by the rotational frequency. Implementation is realized simply by introducing a comparatively large fluidic resistance to an air vent of a fluidic structure downstream of a siphon channel. During temperature decrease at a given TCR, air pressure inside the downstream structure decreases and the fluidic resistance of the air vent slows down air pressure compensation allowing for a thermally induced underpressure to build up temporarily. Thereby the rate of temperature change determines the time course of the underpressure for a given geometry. The thermally induced underpressure pulls liquid against a centrifugal counterpressure above a siphon crest, which triggers the valve or switch. The centrifugal counterpressure (adjusted by rotation) serves as independent control parameter to allow or prevent valving or switching at any TCR. The unit operations are thus compatible to any temperature or centrifugation protocol prior to valving or switching. In contrast to existing methods, this compatibility is achieved at no additional costs: neither additional fabrication steps, nor additional disk space or external means are required besides global temperature control, which is per se needed for the assay. For layout, an analytical model is provided and verified. The TCR actuated unit operations are demonstrated, first, by a stand-alone switch that routes liquid to either one of the two collection chambers (n = 6) and, second, by studying robustness of TCR actuated valving within a microfluidic cartridge for highly integrated nucleic acid testing. Valving could safely be prevented during PCR by compensating the thermally induced underpressure of 3.52 kPa by centrifugal counterpressure at a rotational frequency of 30 Hz with a minimum safety range to valving of 2.03 kPa. Subsequently, a thermally induced underpressure of 2.55 kPa was utilized for robust siphon valving at 3 Hz with a minimum safety range of 2.32 kPa.

2016

F. Schuler, M. Trotter, M. Geltman, F. Schwemmer, S. Wadle, E. Domínguez-Garrido, M. López, C. Cervera-Acedo, P. Santibáñez, F. von Stetten, R. Zengerle, N. Paust
Digital Droplet PCR on Disk
2016 Lab Chip, Band: 16, Seiten: 208 - 216
KurzfassungExisting systems for digital droplet PCR (ddPCR) either suffer from low integration or are difficult to introduce to mass fabrication. Here we present an integrated system that is compatible to mass fabrication and combines emulsification, PCR, and fluorescence readout in a single chamber within a disposable cartridge (disk). Droplets are generated by injecting the sample into fluorinated oil via centrifugal step emulsification. The resulting emulsion is aligned in the PCR and readout zone by capillary action. During thermocycling, gas bubbles generated by degassing are removed by capillary driven transport through tapered regions in the PCR chamber. Thereby, the positioning of the emulsion within the readout zone of the PCR chamber is ensured at any time and no bubbles are present during readout. Manual handling of the disk solely requires pipetting of oil and PCR mix into the inlet structures, placing the disk into the thermocycler and subsequently into a microarray scanner. The functionality of the ddPCR process chain is demonstrated by quantitative detection of the cystic fibrosis causing mutation p.Phe508del, which is of interest for non-invasive prenatal testing (NIPT). The mutation was detected in a concentration range spanning four orders of magnitude. We envision that this work will lay the base for the development of highly integrated sample-to-digital-answer PCR systems that can be employed in routine clinical diagnosis.
F. Schuler, C. Siber, S. Hin, S. Wadle, N. Paust, R. Zengerle, F. von Stetten
Digital droplet LAMP as microfluidic App on standard laboratory devices
2016 Anal Methods-uk, Band: 8, Seiten: 2750 - 2755
KurzfassungDigital nucleic acid amplification methods are a growing research field that allows for absolute quantification of DNA making the need of standard curves redundant. However, most existing digital amplification systems require specialized laboratory devices and costly investments. The required disposable cartridges are device specific and not interchangeable. Here, we present digital droplet loopmediated isothermal amplification (ddLAMP) as a microfluidic App on standard laboratory devices. ddLAMP is implemented on a disposable polymer chip (DropChip) of the format of a standard microscope slide. After DNA denaturation off-chip the reaction mix is emulsified in the DropChip in a mini-centrifuge in 6 minutes. The DropChip is transferred to an in situ thermal cycler for 1 hour of incubation. Afterwards, a fluorescence scan in a microarray scanner is performed. The DropChip allows for absolute quantification with a dynamic range of 15-1500 DNA copies μl-1. Assay conditions were optimized for ddLAMP and comparison of ddPCR and ddLAMP for genomic E. coli DNA reveals very good concordance.
F. Schwemmer, C. E. Blanchet, A. Spilotros, D. Kosse, S. Zehnle, H. D. T. Mertens, M. A. Graewert, M. Rössle, N. Paust, D. I. Svergun, F. von Stetten, R. Zengerle, D. Mark
LabDisk for SAXS: a centrifugal microfluidic sample preparation platform for small-angle X-ray scattering
2016 Lab Chip, Band: 16, Seiten: 1161 - 1170
KurzfassungWe present a centrifugal microfluidic LabDisk for protein structure analysis via small-angle X-ray scattering (SAXS) on synchrotron beamlines. One LabDisk prepares 120 different measurement conditions, grouped into six dilution matrices. Each dilution matrix: (1) features automatic generation of 20 different measurement conditions from three input liquids and (2) requires only 2.5 μl of protein solution, which corresponds to a tenfold reduction in sample volume in comparison to the state of the art. Total hands on time for preparation of 120 different measurement conditions is less than 5 min. Read-out is performed on disk within the synchrotron beamline P12 at EMBL Hamburg (PETRA III, DESY). We demonstrate: (1) aliquoting of 40 nl aliquots for five different liquids typically used in SAXS and (2) confirm fluidic performance of aliquoting, merging, mixing and read-out from SAXS experiments (2.7–4.4% CV of protein concentration). We apply the LabDisk for SAXS for basic analysis methods, such as measurement of the radius of gyration, and advanced analysis methods, such as the ab initio calculation of 3D models. The suitability of the LabDisk for SAXS for protein structure analysis under different environmental conditions is demonstrated for glucose isomerase under varying protein and NaCl concentrations. We show that the apparent radius of gyration of the negatively charged glucose isomerase decreases with increasing protein concentration at low salt concentration. At high salt concentration the radius of gyration (Rg) does not change with protein concentrations. Such experiments can be performed by a non-expert, since the LabDisk for SAXS does not require attachment of tubings or pumps and can be filled with regular pipettes. The new platform has the potential to introduce routine high-throughput SAXS screening of protein structures with minimal input volumes to the regular operation of synchrotron beamlines.
S. Burger, M. Schulz, F. von Stetten, R. Zengerle, N. Paust
Rigorous buoyancy driven bubble mixing for centrifugal microfluidics
2016 Lab Chip, Seiten: 261 - 268
KurzfassungWe present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations.
I. Schwarz, S. Zehnle, T. Hutzenlaub, R. Zengerle, N. Paust
System-level network simulation for robust centrifugal-microfluidic lab-on-a-chip systems
2016 Lab Chip, Band: 16, Seiten: 1873 - 1885
KurzfassungCentrifugal microfluidics shows a clear trend towards a higher degree of integration and parallelization1. This trend leads to an increase in number and density of integrated microfluidic unit operations. The fact that all unit operations are processed by the same common spin protocol turns higher integration into higher complexity. To allow for efficient development anyhow, we introduce advanced lumped models for network simulations in centrifugal microfluidics. These models consider the interplay of centrifugal and Euler pressures, viscous dissipation, capillary pressures and pneumatic pressures. The simulations are fast and simple to set up and allow for the precise prediction of flow rates as well as switching and valving events. During development, channel and chamber geometry variations due to manufacturing tolerances can be taken into account as well as pipetting errors, variations of contact angles, compliant chamber walls and temperature variations in the processing device. As an example for considering these parameters during development, we demonstrate simulation based robustness analysis for pneumatic siphon valving in centrifugal microfluidics. Subsequently the influence of liquid properties on pumping and valving is studied for four liquids relevant for biochemical analysis, namely: water (large surface tension), blood plasma (large contact angle hysteresis), ethanol/water (highly wetting) and glycerine/water (highly viscous). In a second example, we derive a spin protocol to attain a constant flow rate under varying pressure conditions. Both examples show excellent agreement to experimental validations.

2015

F. Schuler, N. Paust, R. Zengerle, F. von Stetten
Centrifugal Step Emulsification can Produce Water in Oil Emulsions with Extremely High Internal Volume Fractions
2015 Micromachines, Band: 6, Nummer: 8, Seiten: 1180 - 1188
KurzfassungThe high throughput preparation of emulsions with high internal volume fractions is important for many different applications, e.g., drug delivery. However, most emulsification techniques reach only low internal volume fractions and need stable flow rates that are often difficult to control. Here, we present a centrifugal high throughput step emulsification disk for the fast and easy production of emulsions with high internal volume fractions above 95%. The disk produces droplets at generation rates of up to 3700 droplets/s and, for the first time, enables the generation of emulsions with internal volume fractions of >97%. The coefficient of variation between droplet sizes is very good (4%). We apply our system to show the in situ generation of gel emulsion. In the future, the recently introduced unit operation of centrifugal step emulsification may be used for the high throughput production of droplets as reaction compartments for clinical diagnostics or as starting material for micromaterial synthesis.
F. Schuler, F. Schwemmer, M. Trotter, S. Wadle, R. Zengerle, F. von Stetten, N. Paust
Centrifugal step emulsification applied for absolute quantification of nucleic acids by digital droplet RPA
2015 Lab Chip, Band: 15, Seiten: 2759 - 2766
KurzfassungAqueous microdroplets provide miniaturized reaction compartments for numerous chemical, biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for the fast and easy production of monodispers droplets. Homogenous droplets with preselectable diameters in a range from 120 μm to 170 μm were generated with coefficients of variation of 2-4% and zero run-in time or dead volume. The droplet diameter depends on the nozzle geometry (depth, width, and step size) and interfacial tensions, only. Droplet size is demonstrated to be independent of the dispersed phase flow rate between 0.01-1 μl/s, proving the robustness of the centrifugal approach. Centrifugal step emulsification can easily be combined with existing centrifugal microfluidic unit operations, is compatible to scalable manufacturing technologies such as thermoforming or injection moulding and enables fast emulsification (> 500 droplets per second and nozzle) with minimal handling effort (2-3 pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute quantification of Listerias monocytogenes DNA concentration standards with a total analysis time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with processing times of about 2 hours, the overall processing time of digital analysis was reduced by more than a factor of 4.
F. Schwemmer, T. Hutzenlaub, D. Buselmeier, N. Paust, F. von Stetten, D. Mark, R. Zengerle, D. Kosse
Centrifugo-pneumatic multi-liquid aliquoting – parallel aliquoting and combination of multiple liquids in centrifugal microfluidics
2015 Lab Chip, Band: 15, Seiten: 3250 - 3258
KurzfassungThe generation of mixtures with precisely metered volumes is essential for reproducible automation of laboratory workflows. Splitting a given liquid into well-defined metered sub-volumes, the so-called aliquoting, has been frequently demonstrated on centrifugal microfluidics. However, so far no solution exists for assays that require simultaneous aliquoting of multiple, different liquids and the subsequent pairwise combination of aliquots with full fluidic separation before combination. Here, we introduce the centrifugo-pneumatic multi-liquid aliquoting designed for parallel aliquoting and pairwise combination of multiple liquids. All pumping and aliquoting steps are based on a combination of centrifugal forces and pneumatic forces. The pneumatic forces are thereby provided intrinsically by centrifugal transport of the assay liquids into dead end chambers to compress the enclosed air. As an example, we demonstrate simultaneous aliquoting of 1.) a common assay reagent into twenty 5 µl aliquots and 2.) five different sample liquids, each into four aliquots of 5 µl. Subsequently, the reagent and sample aliquots are simultaneously transported and combined into twenty collection chambers. All coefficients of variation for metered volumes were between 0.4% - 1.0% for intra-run variations and 0.5% - 1.2% for inter-run variations. The aliquoting structure is compatible to common assay reagents with a wide range of liquid and material properties, demonstrated here for contact angles between 20° and 60°, densities between 789 and 1855 kg / m3 and viscosities between 0.89 and 4.1 mPa s. The centrifugo-pneumatic multi-liquid aliquoting is implemented as a passive fluidic structure into a single fluidic layer. Fabrication is compatible to scalable fabrication technologies such as injection molding or thermoforming and does not require any additional fabrication steps such as hydrophilic or hydrophobic coatings or integration of active valves.
Y. Zhao, F. Schwemmer, S. Zehnle, F. von Stetten, R. Zengerle, N. Paust
Centrifugo-pneumatic sedimentation, re-suspension and transport of microparticles
2015 Lab Chip, Seiten: 4133 - 4137
KurzfassungMicroparticles are widely used as solid phase for affinity based separation. Here, we introduce a new method for automated handling of microparticles in centrifugal microfluidics that is not restricted by the particle size and requires neither auxiliary means such as magnets nor coating of microfluidic structures. All steps are initiated and controlled by the speed of rotation, only. It is based on storage and “on demand” release of pneumatic energy within tuneable time frames: A slow release of the pneumatic energy triggers a first fluidic path through which the supernatant above the sedimented particles is removed. An abrupt release triggers a second path which allows for liquid routing and transport of the re-suspended particles. Re-suspension of particles is thereby achieved by quickly changing the speed of rotation. We demonstrate the exchange of the particle carrier medium with supernatant removal efficiency of more than 99.5% and particle loss below 4%. Re-suspension and subsequent transport of suspended particles shows particle loss below 7%. The method targets for the automation of particle based assays e.g. DNA extractions and immunoassays. It is compatible to monolithic integration and suitable for mass production technologies e.g. thermoforming or injection moulding.
M. Keller, S. Wadle, N. Paust, L. Dreesen, C. Nuese, O. Strohmeier, R. Zengerle, F. von Stetten
Centrifugo-thermopneumatic fluid control for valving and aliquoting applied to multiplex real-time PCR on off-the-shelf centrifugal thermocycler
2015 Rsc Adv, Band: 5, Seiten: 89603 - 89611
KurzfassungWe introduce microfluidic automation of geometrically multiplexed real-time PCR to off-the-shelf Rotor-Gene Q thermocyclers (RGQ, QIAGEN GmbH, Hilden, Germany). For centrifugal fluid control the RGQ provides low and constant rotation of 400 rpm, only. Compatibility to this very limited flexibility of centrifugal actuation is achieved by using thermal gas compression and expansion for valving and aliquoting. In contrast to existing thermo-pneumatic actuation, centrifugo-thermopneumatic (CTP) fluid control employs the induced change of partial vapor pressure by global temperature control as actuation parameter for two new unit operations: CTP siphon valving and CTP two-stage aliquoting. CTP siphon valving was demonstrated to reliably transfer sample liquid in all cases (n = 35) and CTP two-step aliquoting transfers metered aliquots of 18.2 ± 1.2 μl (CV 6.7%, n = 8) into reaction cavities within 5 s (n = 24). Thermal characteristics of CTP two-stage aliquoting were found to be in good agreement with an introduced analytical model (R2 = 0.9876, n = 3). A microfluidic disk segment comprising both new unit operations was used for automation of real-time PCR amplification of Escherichia coli DNA. Required primers and probes were pre-stored in the reaction cavities and a comparison with reference reactions in conventional PCR tubes yielded the same PCR efficiency, repeatability, and reproducibility.
L. Drechsel, M. Schulz, F. von Stetten, C. Moldovanc, R. Zengerle, N. Paust
Electrochemical pesticide detection with AutoDip – a portable platform for automation of crude sample analyses
2015 Lab Chip, Band: 15, Seiten: 704 - 710
KurzfassungLab-on-a-chip devices hold promise for automation of complex workflows from sample to answer with minimal consumption of reagents in portable devices. However, complex, inhomogeneous samples as they occur in environmental or food analysis may block microchannels and thus often cause malfunction of the system. Here we present the novel AutoDip platform which is based on the movement of a solid phase through the reagents and sample instead of transporting a sequence of reagents through a fixed solid phase. A ball-pen mechanism operated by an external actuator automates unit operations such as incubation and washing by consecutively dipping the solid phase into the corresponding liquids. The platform is applied to electrochemical detection of organophosphorus pesticides in real food samples using an acetylcholinesterase (AChE) biosensor. Minimal sample preparation and an integrated reagent pre-storage module hold promise for easy handling of the assay. Detection of the pesticide chlorpyrifos-oxon (CPO) spiked into apple samples at concentrations of 10−7 M has been demonstrated. This concentration is below the maximum residue level for chlorpyrifos in apples defined by the European Commission.
F. Schwemmer, S. Zehnle, D. Mark, F. von Stetten, R. Zengerle, N. Paust
Microfluidic timer for timed valving and pumping in centrifugal microfluidics
2015 Lab Chip, Band: 15, Seiten: 1545 - 1553
KurzfassungAccurate timing of microfluidic operations is essential for the automation of complex laboratory workflows, in particular for the supply of sample and reagents. Here we present a new unit operation for timed valving and pumping in centrifugal microfluidics. It is based on temporary storage of pneumatic energy and time delayed sudden release of said energy. The timer is loaded at a relatively higher spinning frequency. The countdown is started by reducing to a relatively lower release frequency, at which the timer releases after a pre-defined delay time. We demonstrate timing for 1.) the sequential release of 4 liquids at times of 2.7 s ± 0.2 s, 14.0 s ± 0.5 s, 43.4 s ± 1.0 s and 133.8 s ± 2.3 s, 2.) timed valving of typical assay reagents (contact angles 36° - 78°, viscosities 0.9 mPa s - 5.6 mPa s) and 3.) “on demand” valving of liquids from 4 inlet chambers in any user defined sequence controlled by the spinning protocol. The microfluidic timer is compatible to all wetting properties and viscosities of common assay reagents and does neither require assistive equipment, nor coatings. It can be monolithically integrated into a microfluidic test carrier and is compatible to scalable fabrication technologies such as thermoforming or injection molding.
G. Czilwik, I. Schwarz, M. Keller, S. Wadle, S. Zehnle, F. von Stetten, D. Mark, R. Zengerle, N. Paust
Microfluidic vapor-diffusion barrier for pressure reduction in fully closed PCR modules
2015 Lab Chip, Band: 15, Seiten: 1084 - 1091
KurzfassungMicrofluidic systems for polymerase chain reaction (PCR) should be fully closed to avoid vapor loss and to exclude the risk of contaminating the test environment. In closed systems however, the high temperatures of up to 95°C associated with PCR cause high overpressures up to 100 kPa, dominated by the increase of vapor partial pressure upon evaporation. Such high overpressures pose challenges to the mechanical stability of microfluidic chips as well as to the liquid handling in integrated sample-to-answer systems. In this work, we drastically reduce the pressure increase in fully closed PCR systems by integrating a microchannel that serves as a vapor-diffusion barrier (VDB), separating the liquid-filled PCR chamber from an auxiliary air chamber. In such configurations, propagation of vapor from the PCR chamber into the auxiliary air chamber and as a consequence the increase of pressure is limited by the slow diffusion process of vapor through the VDB. At temperature increase from 23°C to 95°C, we demonstrate the reduction of overpressure from more than 80 kPa without the VDB to only 35 kPa with the VDB. We further demonstrate proper function of VDB and its easy integration with downstream processes for PCR based nucleic acid amplification within centrifugal microfluidics. Without integration of the VDB, malfunction due to pressure-induced delamination of the microfluidic chip occurred.
S. Zehnle, F. Schwemmer, R. Bergmann, F. von Stetten, R. Zengerle, N. Paust
Pneumatic siphon valving and switching in centrifugal microfluidics controlled by rotational frequency or rotational acceleration
2015 Microfluid Nanofluid, Band: 19, Seiten: 1259 - 1269
KurzfassungAir-pressure-mediated, pneumatic siphon valves employ temporary storage and subsequent release of pneumatic energy, exclusively controlled by rotation of the disk. Implementation is easy, and robust valves can be integrated in a monolithic way at minimum additional costs. However, so far, pneumatic siphon valving requires deceleration from high to low rotational frequencies. Valve opening is performed always when the rotation of the disk drops below a critical rotational frequency. To overcome this limitation, we introduce new concepts for pneumatic siphon valving which enable operation of the disk at any rotational frequency without unwanted bursts of the siphon valves. Thus, the design space for pneumatic siphon valves in centrifugal microfluidics is significantly extended. Three types of pneumatic siphon valves are presented with release control at (1) rotational frequencies between 25 and 48 Hz, (2) positive rotational accelerations between 1 and 22 Hz s−1, and (3) negative rotational accelerations between 5 and 20 Hz s−1. Finally, we combine two valve types to realize robust switching into two fluidic paths with flow rate ratios of 94/6 and 0/100.
G. Czilwik, T. Messinger, O. Strohmeier, S. Wadle, F. von Stetten, N. Paust, G. Roth, R. Zengerle, P. Saarinen, J. Niittymäki, K. McAllister, O. Sheils, J. O'Leary, D. Mark
Rapid and fully automated bacterial pathogen detection on a centrifugal-microfluidic LabDisk using highly sensitive nested PCR with integrated sample preparation
2015 Lab Chip, Band: 15, Seiten: 3749 - 3759
KurzfassungDiagnosis of infectious diseases suffers from long turnaround times for gold standard culture-based identification of bacterial pathogens, therefore impeding timely specific antimicrobial treatment based on laboratory evidence. Rapid molecular diagnostics-based technologies enable detection of microorganisms within hours however cumbersome workflows and complex equipment still prevent their widespread use in the routine clinical microbiology setting. We developed a centrifugal-microfluidic “LabDisk” system for rapid and highly-sensitive pathogen detection on a point-of-care analyser. The unit-use LabDisk with pre-stored reagents features fully automated and integrated DNA extraction, consensus multiplex PCR pre-amplification and geometrically-multiplexed species-specific real-time PCR. Processing merely requires loading of the sample and DNA extraction reagents with minimal hands-on time of approximately 5 min. We demonstrate detection of as few as 3 colony-forming-units (cfu) of Staphylococcus warneri, 200 cfu of Streptococcus agalactiae, 5 cfu of Escherichia coli and 2 cfu of Haemophilus influenzae in a 200 μL serum sample. The turnaround time of the complete analysis from “sample-to-result” was 3 h and 45 min. The LabDisk consequently provides an easy-to-use molecular diagnostic platform for rapid and highly-sensitive detection of bacterial pathogens without requiring major hands-on time and complex laboratory instrumentation.

2014

L. Zielke, T. Hutzenlaub, D. R. Wheeler, I. Manke, T. Arlt, N. Paust, R. Zengerle, S. Thiele
A Combination of X-Ray Tomography and Carbon Binder Modeling: Reconstructing the Three Phases of LiCoO2 Li-Ion Battery Cathodes
2014 Adv Energy Mater, Band: 4, Seite: 1301617
KurzfassungX-ray tomography allows the active-material domain (LiCoO2) of Li-ion battery cathodes to be imaged, but it is unable to resolve the carbon-binder domain (CBD). Here, a new method for creating a complete 3D representation (virtual design) of all three phases of a cathode is provided; this includes the active-material domain, the CBD, and the electrolyte-filled pore space. It combines X-ray tomographic data of active material with a statistically modeled CBD. Two different statistical CBD morphology models are compared as examples: i) a random cluster model representing a standard mixture of carbon black and polyvenylidene fluoride (PVDF) and ii) a fiber model. The transport parameters are compared in a charged and a discharged cathode. The results demonstrate that the CBD content and morphology changes the ionic and electronic transport parameters dramatically and thus cannot be neglected. Calculations yield that the fiber model shows up to three times higher electrical conductivity at the same CBD content (discharged case) and better ionic diffusion conditions for all CBD contents. In the charged case, the morphology impact on electrical conduction is small. This effective method to generate transport parameters for different CBDs can be transferred to other CBD morphologies and electrodes.
M. Hoehl, E. Schulte Bocholt, A. Kloke, N. Paust, F. von Stetten, R. Zengerle, J. Steigert, A. Slocum
A versatile-deployable bacterial detection system for food and environmental safety based on LabTube-automated DNA purification, LabReader-integrated amplification, readout and analysis
2014 Analyst, Band: 139, Seiten: 2788 - 2798
KurzfassungContamination of foods is a public health hazard that episodically causes thousands of deaths and sickens millions worldwide. To ensure food safety and quality, rapid, low-cost and easy-to-use detection methods 10 are desirable. Here, the LabSystem is introduced for integrated, automated DNA purification, amplification and detection. It consists of a disposable, centrifugally-driven DNA purification platform (LabTube) and the subsequent amplification and detection in a low-cost UV/vis-reader (LabReader). For demonstration of the LabSystem in the context of food safety, purification of Escherichia coli (nonpathogenic E. coli and pathogenic verotoxin-producing E. coli (VTEC)) in water and milk, and the 15 product-spoiler Alicyclobacillus acidoterrestris (A. acidoterrestris) in apple juice was integrated and optimized in the LabTube. Inside the LabReader, the purified DNA was amplified, readout and analyzed using both qualitative isothermal loop-mediated DNA amplification (LAMP) and quantitative real-time PCR. For the LAMP-LabSystem, the combined detection limits for purification and amplification of externally lysed VTEC and A. acidoterrestris is 102-103 cell-equivalents. In the PCR-LabSystem for E. coli cells, the quantification limit is 102 20 cell-equivalents including LabTube-integrated lysis. The demonstrated LabSystem only requires a laboratory centrifuge (to operate the disposable, fully closed LabTube) and the low-cost LabReader for DNA amplification, readout and analysis. Compared with commercial DNA amplification devices, the LabReader improves sensitivity and specificity by the simultaneous readout of four wavelengths and the continuous readout during temperature cycling. The 25 use of a detachable eluate tube as an interface affords semi-automation of the LabSystem, which does not require specialized training. It reduces hands-on time from about 50 to 3 min with only two handling steps: sample input and transfer of the detachable detection tube.
M. Hoehl, M. Weissert, A. Dannenberg, T. Nesch, N. Paust, F. von Stetten, R. Zengerle, A. Slocum, J. Steigert
Centrifugal LabTube platform for fully automated DNA purification and LAMP amplification based on an integrated, low-cost heating-system
2014 Biomed Microdevices, Band: 16, Nummer: 3, Seiten: 375 - 385
KurzfassungThis paper introduces a disposable battery-driven heating system for loop-mediated isothermal DNA amplification (LAMP) inside a centrifugally-driven DNA purification platform (LabTube). We demonstrate LabTube-based fully automated DNA purification of as low as 100 cell-equivalents of verotoxin-producing Escherichia coli (VTEC) in water, milk and apple juice in a laboratory centrifuge, followed by integrated and automated LAMP amplification with a reduction of hands-on time from 45 to 1 min. The heating system consists of two parallel SMD thick film resistors and a NTC as heating and temperature sensing elements. They are driven by a 3 V battery and controlled by a microcontroller. The LAMP reagents are stored in the elution chamber and the amplification starts immediately after the eluate is purged into the chamber. The LabTube, including a microcontroller-based heating system, demonstrates contamination-free and automated sample-to-answer nucleic acid testing within a laboratory centrifuge. The heating system can be easily parallelized within one LabTube and it is deployable for a variety of heating and electrical applications.
A. Kloke, A. R. Fiebach, S. Zhang, L. Drechsel, S. Niekrawietz, M. Hoehl, R. Kneusel, K. Panthel, J. Steigert, F. von Stetten, R. Zengerle, N. Paust
The LabTube – A novel microfluidic platform for assay automation in laboratory centrifuges
2014 Lab Chip, Band: 14, Seiten: 1527 - 1537
KurzfassungAssay automation is the key for successful transformation of modern biotechnology into routine workflows. Yet, it requires considerable investment in processing devices and auxiliary infrastructure, which is not cost-efficient for laboratories with low or medium sample throughput or point-of-care testing. To close this gap, we present the LabTube platform, which is based on assay specific disposable cartridges for processing in laboratory centrifuges. LabTube cartridges comprise interfaces for sample loading and downstream applications and fluidic unit operations for release of prestored reagents, mixing, and solid phase extraction. Process control is achieved by a centrifugally-actuated ballpen mechanism. To demonstrate the workflow and functionality of the LabTube platform, we show two LabTube automated sample preparation assays from laboratory routine: DNA extractions from whole blood and purification of His-tagged proteins. Equal DNA and protein yield were observed compared to manual reference runs, while LabTube automation could significantly reduce the hands-ontime to one minute per extraction.
L. Zielke, T. Hutzenlaub, D. R. Wheeler, C.-W. Chao, I. Manke, A. Hilger, N. Paust, R. Zengerle, S. Thiele
Three-Phase Multiscale Modeling of a LiCoO 2 Cathode: Combining the Advantages of FIB–SEM Imaging and X-Ray Tomography
2014 Adv Energy Mater, Band: 5, Seite: 1401612
KurzfassungLiCoO 2 electrodes contain three phases, or domains, each having specific-intended functions: ion-conducting pore space, lithium-ion-reacting active material, and electron conducting carbon-binder domain (CBD). Transport processes take place in all domains on different characteristic length scales: from the micrometer scale in the active material grains through to the nanopores in the carbon-binder phase. Consequently, more than one imaging approach must be utilized to obtain a hierarchical geometric representation of the electrode. An approach incorporating information from the micro- and nanoscale to calculate 3D transport-relevant properties in a largereconstructed active domain is presented. Advantages of focused ion beam/ scanning electron microscopy imaging and X-ray tomography combined by a spatial stochastic model, validated with an artifi cially produced reference structure are used. This novel approach leads to signifi cantly different transport relevant properties compared with previous tomographic approaches: nanoporosity of the CBD leads to up to 42% additional contact area between active material and pore space and increases ionic conduction by a factor of up to 3.6. The results show that nanoporosity within the CBD cannot be neglected.
T. Hutzenlaub, S. Thiele, N. Paust, R. Spotnitz, R. Zengerle, C. Walchshofer
Three-dimensional electrochemical Li-ion battery modelling featuring a focused ion-beam/scanning electron microscopy based three-phase reconstruction of a LiCoO2 cathode
2014 Electrochim Acta, Band: 115, Seiten: 131 - 139
KurzfassungWe combine a three-phase, three-dimensional reconstruction of a LiCoO2battery cathode based onfocused ion-beam/scanning electron microscopy (FIB/SEM) imaging with an electrochemical model. Themodel considers the electric potential and lithium/salt concentration distribution in both the liquid elec-trolyte and the solid active-material phases. In contrast to previously presented models, we spatiallyresolve the carbon-binder phase to provide a more realistic description of the electric potential. Weobserve that carbon-binder coverage of the solid electrolyte interface (SEI) impedes local surface reac-tions and thus affects lithium redistribution. For the considered cathode, the total surface to volumeratio of the SEI is reduced from 11.2 × 105to 6.5 × 105m2m−3when the carbon-binder phase is modelledexplicitly. This leads to increased inhomogeneity of the lithium concentration in active-material grainsduring charging.Additionally, we study lithium/salt concentration in the electrolyte, revealing gradients between 0.9and 1.5 kmol m−3depending on the distance to the separator. This is significant because the lithium/saltconcentration directly affects the ion transport properties of the electrolyte.
L. Zielke, A. Fallisch, N. Paust, R. Zengerle, S. Thiele
Tomography based screening of flow field / current collector combinations for PEM water electrolysis
2014 Rsc Adv, Band: 4, Seiten: 58888 - 58894
KurzfassungCurrent collectors in PEM water electrolysis perform several functions that influence overall performance. These include conducting heat and electrons, as well as transporting water and gas. X-ray tomography, standardized reconstruction, and calculation methods are used to compare the morphological and transport parameters of eight different current collectors functioning as flow fields for PEM water electrolysis. We find simple exponential relations between through-plane thermal conductivity l and porosity p (l20 C(p) ¼ 1749p 1.306 4.420), as well as between through-plane electrical conductivity s and water permeability K (s(K) ¼ 10 6 K 0.6376). In addition, we use both local and global concepts to investigate the pore space of current collectors. We hereby investigate homogeneity and characteristic sizes, like mean pore diameter or mean distance between solid parts at the catalytic interface. Moreover, we find that the local concept of mean chord lengths can be used to explain electrical and thermal conductivity anisotropies. These chords can be used to predict the direction of the largest conductivity for fibrous current collectors.

2013

N. Wangler, M. Welsche, M. Blazek, M. Blessing, M. Vervliet-Scheebaum, R. Reski, C. Müller, H. Reinecke, J. Steigert, G. Roth, R. Zengerle, N. Paust
Bubble Jet agent release cartridge for chemical single cell stimulation
2013 Biomed Microdevices, Band: 15, Seiten: 1 - 8
KurzfassungWe present a new method for the distinct specific chemical stimulation of single cells and small cell clusters within their natural environment. By single-drop release of chemical agents with droplets in size of typical cell diameters (d <30 μm) on-demand micro gradients can be generated for the specific manipulation of single cells. A single channel and a double channel agent release cartridge with integrated fluidic structures and integrated agent reservoirs are shown, tested, and compared in this publication. The single channel setup features a fluidic structure fabricated by anisotropic etching of silicon. To allow for simultaneous release of different agents even though maintaining the same device size, the second type comprises a double channel fluidic structure, fabricated by photolithographic patterning of TMMF. Dispensed droplet volumes are V015 pl and V0 10 pl for the silicon and the TMMF based setups, respectively. Utilizing the agent release cartridges, the application in biological assays was demonstrated by hormone-stimulated premature bud formation in Physcomitrella patens and the individual staining of one single L 929 cell within a confluent grown cell culture.
C. Cupelli, T. Borchardt, T. Steiner, N. Paust, R. Zengerle, M. Santer
Leukocyte enrichment based on a modified pinched flow fractionation approach
2013 Microfluid Nanofluid, Band: 14, Nummer: 3-4, Seiten: 551 - 563
KurzfassungIn this paper, a simple and robust design for a passive hydrodynamic cell sorter based on pinched flow-field fractionation is presented and analyzed. Two principal layouts of the sorter are discussed and investigated experimentally as well as numerically based on the dissipative particle dynamics (DPD) method. Experimentally, design 1 approximately sorts 87 % of the erythrocytes to their designated outlet, while 100 % of the leukocytes branch correctly. This also holds for design 2 differing merely in the direction of the outlet for erythrocytes, but here only 69 % of the red blood cells are redirected to the designated outlet. This behavior can be elucidated by employing DPD simulations, where erythrocytes advected with the flow are modeled explicitly. Our results suggest that if a cell sorter is designed to operate at high throughput, its layout may not entirely rely on commonly assumed idealizing conditions, because cells cannot be considered as point-like, isolated objects following definite stream lines. Hydrodynamic forces originating from the cells as extended objects must be taken into account.

2012

S. Zehnle, F. Schwemmer, G. Roth, F. von Stetten, R. Zengerle, N. Paust
Centrifugo-dynamic inward pumping of liquids on a centrifugal microfluidic platform
2012 Lab Chip (Lab on a Chip) 2012, Band: 12, Seiten: 5142 - 5145
KurzfassungWe present a method to pump liquids in a centrifugal microfluidic spinning disk from a radial outward position to a radial inward position. Centrifugal forces are applied to compress air in a cavity, this way storing pneumatic energy. The cavity is connected to an outlet channel having a lower hydraulic resistance compared to the inlet channel. The stored pneumatic energy is quickly released by fast reduction of rotational frequency. This way liquid is transported mainly through the channel with lower resistance, directing the liquid radially inwards. Pump efficiencies of .75% per pump cycle have been demonstrated for water, ethanol, a highly viscous lysis buffer and whole blood. By employing three pump cycles, water has been pumped radially inwards with an efficiency of .90%. The inward pumping requires centrifugation only, which is intrinsically available on every centrifugal microfluidic platform.

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A. Ernst, K. Mutschler, L. Tanguy, N. Paust, R. Zengerle, P. Koltay
Numerical Investigations on Electric Field Characteristics with Respect to Capacitive Detection of Free-Flying Droplets
2012 sensors, Band: 12, Seiten: 10550 - 10565
KurzfassungIn this paper a multi-disciplinary simulation of a capacitive droplet sensor based on an open plate capacitor as transducing element is presented. The numerical simulations are based on the finite volume method (FVM), including calculations of an electric field which changes according to the presence of a liquid droplet. The volume of fluid (VOF) method is applied for the simulation of the ejection process of a liquid droplet out of a dispenser nozzle. The simulations were realised using the computational fluid dynamic (CFD) software CFD ACE+. The investigated capacitive sensing principle enables to determine the volume of a micro droplet passing the sensor capacitor due to the induced change in capacity. It could be found that single droplets in the considered volume range of 5 nL < Vdrop < 100 nL lead to a linear change of the capacity up to ΔQ < 30 fC. The sensitivity of the focused capacitor geometry was evaluated to be Si = 0.3 fC/nL. The simulation results are validated by experiments which exhibit good agreement.
A. Tropmann, N. Lass, N. Paust, T. Metz, C. Ziegler, R. Zengerle, P. Koltay
Pneumatic Dispensing of Nano- to Picoliter Droplets of Liquid Metal with the StarJet Method for Rapid Prototyping of Metal Microstructures
2012 Microfluid Nanofluid, Band: 12, Seiten: 75 - 84
KurzfassungThis work presents a new, simple and robust, pneumatically actuated method for the generation of liquid metal micro droplets in the nano- to picoliter range. The so called StarJet dispenser utilizes a star-shaped nozzle geometry that stabilizes liquid plugs in its center by means of capillary forces. Single droplets of liquid metal can be pneumatically generated by interaction of the sheathing gas flow in the outer grooves of the nozzle and the liquid metal. For experimental validation, a print head was build consisting of silicon chips with a star-shaped nozzle geometry and a heated actuator (up to 280 °C). The silicon chips are fabricated by Deep Reactive Ion Etching (DRIE). Chip designs with different star-shaped geometries were able to generate droplets with diameters in the range of the corresponding nozzle diameters. The StarJet can be operated in two modes: Either continuous droplet dispensing mode or drop on demand (DoD) mode. The continuous droplet generation mode for a nozzle with 188 µm diameter shows tear-off frequencies between 25 Hz and 120 Hz, while droplet diameters remain constant at 210 µm for each pressure level. Metal columns were printed with a thickness of 0.5 to 1.0 mm and 30 mm height (aspect ratio >30) to demonstrate the directional stability of droplet ejection and its potential as a suitable tool for direct prototyping of metal microstructures.

2011

Marc Karle, Johannes Wöhrle, Junichi Miwa, Nils Paust, Günter Roth, Roland Zengerle, Felix von Stetten
Controlled counter-flow motion of magnetic bead chains rolling along microchannels
2011 Microfluid Nanofluid, Band: 10, Nummer: 4, Seiten: 935 - 939
KurzfassungWe demonstrate controlled transport of superparamagnetic beads in the opposite direction of a laminar flow. A permanent magnet assembles 200 nm magnetic particles into about 200 lm long bead chains that are aligned in parallel to the magnetic field lines. Due to a magnetic field gradient, the bead chains are attracted towards the wall of a microfluidic channel. A rotation of the permanent magnet results in a rotation of the bead chains in the opposite direction to the magnet. Due to friction on the surface, the bead chains roll along the channel wall, even in counter-flow direction, up to at a maximum counter-flow velocity of 8 mm s(-1). Based on this approach, magnetic beads can be accurately manoeuvred within microfluidic channels. This counter-flow motion can be efficiently be used in Lab-on-a-Chip systems, e.g. for implementing washing steps in DNA purification.
N Wangler, L Gutzweiler, K Kalkandjiev, C Müller, F Mayenfels, H Reinecke, R Zengerle, N Paust
High-resolution permanent photoresist laminate TMMF for sealed microfluidic structures in biological applications
2011 J Micromech Microeng, Band: 21, Seite: 095009
KurzfassungWe demonstrate the use of photosensitive epoxy laminate TMMF S2045 for the fabrication and sealing of tapered microfluidic channels. The 45 μm thick resist enables the fabrication of shallow sealed cavities featuring extreme aspect ratios of less than 1:40 (h = 45 μm, w = 2000 μm). It also provides high resolution and enables minimum feature sizes of 10 μm. For the fabrication of free-standing structures, an aspect ratio of up to 7:1 was achieved. The dry-film photoresist can be applied easily by lamination onto structured substrates. The total thickness variation of the resist across a 100 mm wafer was determined to be less than ±0.6 μm. Process parameters for the fabrication and sealing of various micro-channels are discussed and optimized in this paper. The main focus was to minimize thermal impact during lamination, soft-bake, exposure and post–exposure bake, which could lead to lid sagging or channel clogging due to liquefaction of uncured resist. We tested TMMF according to ISO 10995-5 and found it to be non-cytotoxic, enabling its use for biological applications. Swelling of less than 5% for incubation of the dry-film resist in several biologically relevant solvents, buffers and cleaning solutions was observed.
T. Hutzenlaub, N. Paust, R. Zengerle, C. Ziegler
The effect of wetting properties on bubble dynamics and fuel distribution in the flow field of direct methanol fuel cells
2011 J Power Sources, Band: 196, Seiten: 8048 - 8056
KurzfassungWe investigate CO2 bubble dynamics on the anode side of a direct methanol fuel cell (DMFC). In contrast to previous studies, we analyse the effect of both channel wall and diffusion layer wettability by observing two-phase flow from the side at different mean velocities of the fuel supply. Hydrophobic and hydrophilic flow channel surfaces are compared experimentally. The hydrophilic flow channel leads to a minimum pressure drop along the channel. Bubbles show virtually no pinning and consequently travel at approximately the mean fuel velocity inside the channel. In contrast to this, we observe bubble pinning in the hydrophobic flow channels. The critical fuel velocities necessary for detachment of the bubbles mainly depends on bubble length. We identify and describe a new bubble bypass configuration where fuel bypass channels are solely generated in a favourable position underneath a blocking bubble along the diffusion layer. This enforces fuel to bypass the CO2 bubble at a large relative velocity close to the diffusion layer, thus enhancing mass transfer. Our experimental findings are in excellent agreement with a CFD/analytical model. This model allows for quantitative prediction of average bypass flow velocity.

2010

Tobias Metz, Nils Paust, Roland Zengerle, Peter Koltay
Capillary driven movement of gas bubbles in tapered structures
2010 Microfluid Nanofluid, Band: 9, Seiten: 341 - 355
KurzfassungThis article presents a study on the capillary driven movement of gas bubbles confined in tapered channel configurations. These configurations can be used to transport growing gas bubbles in micro fluidic systems in a passive way, i.e. without external actuation. A typical application is the passive degassing of CO2 in micro direct methanol fuel cells (lDMFC). Here, a one-dimensional model for the bubble movement in wide tapered channels is derived and calibrated by experimental observations. The movement of gas bubbles is modelled on straight trajectories based on a balance of forces. The bubble geometry is considered as three dimensional. In the development of the model, the effects of surface tension, inertia, viscosity, dynamic contact angle and thin film deposition are considered. It is found that in addition to viscous dissipation, the dynamics related to the contact line—dynamic contact angle and thin film deposition—are essential to describe the gas bubble’s movement. Nevertheless, it was also found that both of these effects, as modelled within this work, have similar impact and are hard to distinguish. The model was calibrated against experiments in a parameter range relevant for the application of travelling gas bubbles in passive degassing structures for lDMFCs.

2009

N. Paust, Ch. Litterst, T. Metz, M. Eck, Ch. Ziegler, R. Zengerle, P. Koltay
Capillary-driven pumping for passive degassing and fuel supply in direct methanol fuel cells
2009 Microfluid Nanofluid, Band: 7, Seiten: 531 - 543
KurzfassungIn this paper we present a new concept of creating and using capillary pressure gradients for passive degassing and passive methanol supply in direct methanol fuel cells (DMFCs). An anode flow field consisting of parallel tapered channels structures is applied to achieve the passive supply mechanism. The flow is propelled by the surface forces of deformed CO2 bubbles, generated as a reaction product during DMFC operation. This work focuses on studying the influence of channel geometry and surface properties on the capillary-induced liquid flow rates at various bubbly gas flow rates. Besides the aspect ratios and opening angles of the tapered channels, the static contact angle as well as the effect of contact angle hysteresis has been identified to significantly influence the liquid flow rates induced by capillary forces at the bubble menisci. Applying the novel concept, we show that the liquid flow rates are up to thirteen times higher than the methanol oxidation reaction on the anode requires. Experimental results are presented that demonstrate the continuous passive operation of a DMFC for more than 15 h.
Paust, N, Krumbholz, S, Munt, S, Müller, C, Koltay, P, Zengerle, R, Ziegler, C
Self-Regulating Passive Fuel Supply for Small Direct Methanol Fuel Cells Operating in All Orientations
2009 J Power Sources, Band: 192, Seiten: 442 - 450
KurzfassungA microfluidic fuel supply concept for passive and portable Direct Methanol Fuel Cells (DMFCs) that operate in all spatial orientations is presented. The concept has been proven by fabricating and testing a passive DMFC prototype. Methanol transport at the anode is propelled by the surface energy of deformed carbon dioxide bubbles, generated as a reaction product during DMFC operation. The experimental study reveals that in any orientation, the proposed pumping mechanism transports at least 3.5 times more methanol to the reactive area of the DMFC than the stoichiometry of the methanol oxidation would require to sustain DMFC operation. Additionally, the flow rates closely follow the applied electric load; hence the pumping mechanism is self-regulating. Oxygen is supplied to the cathode by diffusion and the reaction product water is transported out of the fuel cell along a continuous capillary pressure gradient. Results are presented that demonstrate the continuous passive operation for more than 40 hours at ambient temperature with a power output of p = 4 mW cm-2 in the preferred vertical orientation and of p = 3.2 mW cm-2 in the least favourable horizontal orientation with the anode facing downwards. Keywords: passive DMFC; self-regulating fuel supply; capillary-force-driven bubble pump

2008

T. Metz, J. Viertel, C. Müller, S. Kerzenmacher, N. Paust, R. Zengerle, P. Koltay
Passive water management for µfuel-cells using capillary microstructures
2008 J Micromech Microeng, Band: 18, Nummer: 10
KurzfassungIn this work we present a novel system for the passive water management in polymer electrolyte fuel cells (PEMFC) based on capillary effects in microstructures. The system removes abundant water that occurs at low temperatures at a fuel cell cathode and secures the humidity of the electrolyte membrane on higher temperatures. Liquid water is removed by hydrophilic gas supply channels with a tapered cross section as presented previously, and further transported by a system of capillary channels and a layer of nonwoven material. To prevent the membrane from running dry, a storage area in the nonwoven layer is introduced, controlled by a novel passive capillary overflow valve. The valve controls whether water is stored or finally disposed by gravity and evaporation. Experiments in a model system show that the nonwoven material is capable of removing all liquid water that can be produced by the fuel cell. A miniaturized fuel cell utilizing the novel water removal system was fabricated and experiments show that the system can stabilize the performance during changes of electrical load. Clearing the drowned miniaturized fuel cell flow field was proven and required 2 min. To make the capillary effects available for the originally hydrophobic graphite composite materials that were used to fabricate the flow fields, hydrophilic grafting based on photochemistry was applied to the material and contact angles of about 40° could be achieved and preserved for at least three months.

2007

Metz,T., Paust,N., Müller,C., Zengerle,R., Koltay,P.
Passive water removal in fuel cells by capillary droplet actuation
2007 Sensors & Actuators: A.Physical, Band: Special Issue MEMS 2007

Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften

Jahre: 2020 | 2019 | 2015

zurück zur Übersicht aller Publikationen

2020

J. F. Hess, T.A. Kohl, M. Kotrová, K. Roensch, T. Paprotka, V. Mohr, T. Hutzenlaub, M. Brüggemann, R. Zengerle, S. Niemann, N. Paust
Library preparation for next generation sequencing: A review of automation strategies
2020 Biotechnol Adv, Seite: 107537
KurzfassungNext generation sequencing is in the process of evolving from a technology used for research purposes to one which is applied in clinical diagnostics. Recently introduced high throughput and benchtop instruments offer fully automated sequencing runs at a lower cost per base and faster assay times. In turn, the complex and cumbersome library preparation, starting with isolated nucleic acids and resulting in amplified and barcoded DNA with sequencing adapters, has been identified as a significant bottleneck. Library preparation protocols usually consist of a multistep process and require costly reagents and substantial hands-on-time. Considerable emphasis will need to be placed on standardisation to ensure robustness and reproducibility. This review presents an overview of the current state of automation of library preparation for next generation sequencing. Major challenges associated with library preparation are outlined and different automation strategies are classified according to their functional principle. Pipetting workstations allow high-throughput processing yet offer limited flexibility, whereas microfluidic solutions offer great potential due to miniaturisation and decreased investment costs. For the emerging field of single cell transcriptomics for example, microfluidics enable singularisation of tens of thousands of cells in nanolitre droplets and barcoding of the RNA to assign each nucleic acid sequence to its cell of origin. Finally, two applications, the characterisation of bacterial pathogens and the sequencing within human immunogenetics, are outlined and benefits of automation are discussed.

2019

J. F. Hess, S. Zehnle, P. Juelg, T. Hutzenlaub, R. Zengerle, N. Paust
Review on pneumatic operations in centrifugal microfluidics
2019 Lab Chip, Band: 22, Seiten: 3745 - 3770
KurzfassungCentrifugal microfluidics allows for miniaturization, automation and parallelization of laboratory workflows. The fact that centrifugal forces are always directed radially outwards has been considered a main drawback for the implementation of complex workflows leading to the requirement of additional actuation forces for pumping, valving and switching. In this work, we review and discuss the combination of centrifugal with pneumatic forces which enables transport of even complex liquids in any direction on centrifugal systems, provides actuation for valving and switching, offers alternatives for mixing and enables accurate and precise metering and aliquoting. In addition, pneumatics can be employed for timing to carry out any of the above listed unit operations in a sequential and cascaded manner. Firstly, different methods to generate pneumatic pressures are discussed. Then, unit operations and applications that employ pneumatics are reviewed. Finally, a tutorial section discusses two examples to provide insight into the design process. The first tutorial explains a comparatively simple implementation of a pneumatic siphon valve and provides a workflow to derive optimum design parameters. The second tutorial discusses cascaded pneumatic operations consisting of temperature change rate actuated valving and subsequent pneumatic pumping. In conclusion, combining pneumatic actuation with centrifugal microfluidics allows for the design of robust fluidic networks with simple fluidic structures that are implemented in a monolithic fashion. No coatings are required and the overall demands on manufacturing are comparatively low. We see the combination of centrifugal forces with pneumatic actuation as a key enabling technology to facilitate compact and robust automation of biochemical analysis.

2015

O. Strohmeier, M. Keller, F. Schwemmer, S. Zehnle, D. Mark, F. von Stetten, R. Zengerle, N. Paust
Centrifugal microfluidic platforms: advanced unit operations and applications
2015 Chem Soc Rev, Band: 44, Seiten: 6187 - 6229
KurzfassungCentrifugal microfluidics has evolved into a mature technology. Several major diagnostic companies either have products on the market or are currently evaluating centrifugal microfluidics for product development. The fields of application are widespread and include clinical chemistry, immunodiagnostics and protein analysis, cell handling, molecular diagnostics, as well as food, water, and soil analysis. Nevertheless, new fluidic functions and applications that expand the possibilities of centrifugal microfluidics are being introduced at a high pace. In this review, we first present an up-to-date comprehensive overview of centrifugal microfluidic unit operations. Then, we introduce the term “process chain” to review how these unit operations can be combined for the automation of laboratory workflows. Such aggregation of basic functionalities enables efficient fluidic design at a higher level of integration. Furthermore, we analyze how novel, ground-breaking unit operations may foster the integration of more complex applications. Among these are the storage of pneumatic energy to realize complex switching sequences or to pump liquids radially inward, as well as the complete pre-storage and release of reagents. In this context, centrifugal microfluidics provides major advantages over other microfluidic actuation principles: the pulse-free inertial liquid propulsion provided by centrifugal microfluidics allows for closed fluidic systems that are free of any interfaces to external pumps. Processed volumes are easily scalable from nanoliters to milliliters. Volume forces can be adjusted by rotation and thus, even for very small volumes, surface forces may easily be overcome in the centrifugal gravity field which enables the efficient separation of nanoliter volumes from channels, chambers or sensor matrixes as well as the removal of any disturbing bubbles. In summary, centrifugal microfluidics takes advantage of a comprehensive set of fluidic unit operations such as liquid transport, metering, mixing and valving. The available unit operations cover the entire range of automated liquid handling requirements and enable efficient miniaturization, parallelization, and integration of assays.

Kurzbeiträge

Jahre: 2011

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2011

Daniel Mark, Günter Roth, Dominique Kosse, Nils Paust, Roland Zengerle, Felix von Stetten
Assay-Automatisierung als Dienstleistung - Mikrofluidische Integration von Laborprozessen durch den Lab-on-a-Chip Design- & Foundry-Service
2011 Labo, Band: April, Seiten: 10 - 13

Vorträge

Jahre: 2017 | 2013

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2017

F. Schuler, S. Wadle, N. Borst, M. Schulz, L. Becherer, J. Li, M. Specht, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten
A Technology Platform for Digital Nucleic Acid Diagnostics at the Point of Care (invited talk)
2017 3. Münchner point-of-care testing symposium, Deutsche Gesellschaft für Klinische Chemie und Laboratoriumsmedizin (DGKL), München, 13.-15. 3. 2017
F. Schuler, N. Borst, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten
Centrifugal Step Emulsification Allows Miniaturized Digital Droplet-RPA,-LAMP and -PCR on the Centrifugal Microfluidic Platform (invited talk)
2017 9th Annual lab-on-a-chip & microfluidics Conference, Selectbio, Munich, 10.-11.5. 2017

2013

R. Zengerle, D. Mark, O. Strohmeier, D. Kosse, N. Paust, F. von Stetten, G. Czilwik, T. van Oordt, M. Keller, J. Drexler
LabDisk - a set of novel centrifugal microfluidc unit operations enables point of care sample-to-answer nucleic acid testing
2013 Gordon Research Conference on ”Physics and Chemistry of Microfluidics: Challenges, Advances and New Technologies for Diagnostics” in Lucca, Tuscany, Italy , 09. – 14.06.2013
F. von Stetten, A. Kloke, A. Fiebach, L. Drechsel, S. Zhang, N. Paust, J. Steigert, R. Zengerle
LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
2013 Gordon Research Conference on ”Physics and Chemistry of Microfluidics: Challenges, Advances and New Technologies for Diagnostics” in Lucca, Tuscany, Italy , 09. – 14.06.2013

Konferenzbeiträge

Jahre: 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007

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2023

Y.-K. Lai, J. F. Hess, N. Paust
Centrifugal gravity enables void-free priming of dead-end nanoliter cavities
2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023
T.-T. Truong, K. Mikloska, N. Paust, T. Hutzenlaub, L. Kubetzko, S. Derer, N. von Bubnoff, P. Juelg
Comparison of DNA reference material for pre analytics : Nucleosomal plasma spike ins reveal true recovery efficiencies of circulating cell free DNA extractions
2023 ISMRC 2023 - 13th International Symposium on Minimal Residual Cancer, Hamburg, 02.-04.05.2023
S. Murad, M. Heyer, F. Lickert, J. Menges, S. Calabrese, T. Hutzenlaub, N. Paust, P. Juelg
Fast and bubble-free filling of nano-imprinted high-density picoliter well arrays for digital assays enabled by centrifugal microfluidics
2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023
E. Mahmodi Arjmand, F. Schlenker, G. Grether, T. Tu Troung, T. Hutzenlaub, R. Zengerle, N. Paust, J. Lüddecke, P. Juelg
Gleichzeitige Extraktion von extrazellulären Vesikeln und zellfreier DNA aus einer einzigen Blutprobe durch zentrifugale Mikrofluidik
2023 Mikrosystemtechnik Kongress 2023, Dresden, 23.-25.10.2023
B. Johannsen, D. Baumgartner, M. Karpíšek, D. Stejskal, N. Paust, R. Zengerle, K. Mitsakakis
Integration of a bead-based immunoassay on a commercial PCR-performing POC device
2023 Eurosensors 2023, Lecce, Italy, 10. - 13.09.2023
T. Tu-Truong, Y. Kaku, S. ElGenk, M. Bösenberg, H. Sültmann, T. Gemoll, N. von Bubnoff, E. Dazert, L. Kubetzko, S. Derer, M. Oberländer, A. Katalinic, R. Deck, C. Sina, H. Busch, S. Kartmann, J. Lüddecke, T. Hutzenlaub, N. Paust, P. Juelg
Robotic centrifugal microfluidics: a novel automation platform for large sample volume applications demonstrated by cell-free DNA isolation
2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023
J. Schlanderer, J. Lüddecke, A. Golubov, W. Grasse, T. A. Kohl, C. Metzger-Boddien, S. Niemann, C. Pilloni, S. Plesnik, B. Raya, B. Shresta, R. Zengerle, M. Beutler, H. Hoffmann, N. Paust
Two-Stage Tuberculosis Diagnostics: Combining Centrifugal Microfluidics at the Point-of-Care with subsequent Antibiotic Resistance Profiling by Targeted NGS
2023 MicroTAS 2023, Katovice/Poland, 15.-19.10.2023
J. Schlanderer, M. Beutler, W. Grasse, T. A. Kohl, J. Lüddecke, S. Niemann, H. Hoffmann, N. Paust
Two-stage tuberculosis diagnostics: centrifugal microfluidics at the point of care with subsequent antibiotic resistance profiling by tNGS
2023 Eurosensors 2023, Lecce, Italy, 10. - 13.09.2023

2022

T. Tu Truong, F. Schlenker, L. Karkossa, E. M. Arjmand, G. Grether, J. Lüddecke, U. A. Walker, S. Giaglis, N. Paust, T. Hutzenlaub, P. Juelg
Towards standardization of pre-analytics: Highly efficient platelet-poor-plasma generation for ccfmtDNA analysis on a centrifugal microfluidic platform
2022 EACR Liquid Biopsy, Bergamo, Italy, May 24-26, 2022

2021

J.-N. Klatt, T.-L. Dinh, O. Schilling, R. Zengerle, F. Schmidt, T. Hutzenlaub, N. Paust
Automation of Solid Phase Extraction for Peptide Desalting by Centrifugal Microfluidics
2021 37th International Symposium on Microscale Separations and Bioanalysis 2021, Boston/USA (online), 12.-15.07.2021
J.-N. Klatt, T.J. Dinh, N. Paust, R. Zengerle, F. Schmidt, O.Schilling, T. Hutzenlaub
Automation of peptide desalting by centrifugal microfluidics
2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
B. Johannsen, D. Baumgartner, L. Karkossa, L. Müller, N. Paust, M. Karpíšek, N. Bostanci, R. Zengerle, K. Mitsakakis
Detection of systemic and oral inflammation biomarkers through biochemical and microfluidic integration
2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
D. Kainz, B. Breiner, R. Zengerle, N. Paust, T. Hutzenlaub, S. M. Früh
Determining binding kinetics of a PCT lateral flow assay during runtime
2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
P. Juelg, E. Kipf, M. Specht, J. Menges, M. Fillies, C. Eckert, N. Paust, R. Zengerle, M. Lehnert, T. Hutzenlaub
Die MRD Disk: Automatisiertes Monitoring Minimaler Resterkrankung durch hochsensitive, zentrifugal-mikrofluidische Multiplex-qPCR / The MRD disk: automated minimal residual disease monitoring by highly sensitive centrifugal microfluidic multiplex qPCR
2021 MST
L. Niebling, S. Burger, N. Paust, A. R. Homann
Fast and on-site animal species identification in processed meat
2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
F. Schlenker, L. Karkossa, N. Paust, R. Zengerle, S. Giaglis, U. A. Walker, T. Hutzenlaub, P. Juelg
Generation of platelet poor plasma for circulating cell-free mitochondrial DNA analysis on a centrifugal microfluidic platform
2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021
J. Schlanderer, J. Lüddecke, R. Zengerle, N. Paust
Large sample volume management on centrifugal microfluidic cartridges
2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021
D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. Mitsakakis
Microfluidic-based molecular analysis of plant psts for insecticide resistance management (Superpests-Disk)
2021
L. Becherer, J.F. Hess, S. Frischmann, M. Bakheit, H. Nitschko, S. Stinco, F. Zitz, H. Hofer, G. Porro, F. Hausladen, K. Stock, D. Drossart, H. Wurm, H. Kuhn, D. Huber, T. Hutzenlaub, N. Paust, M. Keller, O. Strohmeier, S. Wadle, N. Borst, R. Zengerle, F. von Stetten
Point-of-Care System for HTLV-1 Proviral Load Quantification by Digital Mediator Displacement LAMP
2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021
D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. Mitsakakis
SuperPests LabDisk: a microfluidic-based molecular diagnostic platform for detection of biotypes, resistance mutations and plant pathogens P3.021
2021 Biosensors, Haeundae-gu, South Korea (online), 26. – 29.07.2021
E. Mahmodi Arjmand, G. Grether, R. Zengerle, N. Paust, J. Lüddecke
Waste liquid assisted flow-switching on a centrifugal microfluidic platform
2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021

2020

A. Brunauer, B. Breiner, S. Hennig, D. Kainz, R. Verboket, B. Johannsen, D. Baumgartner, K. Mitsakakis, L. Gutzweiler, Z. Shu, P. Koltay, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, S. M. Früh
Actuation principles for bioanalytical platforms to combat infectious diseases
2020 Virtual EMBL Conference: Microfluidics: Designing the Next Wave of Biological Inquiry 2020, 13.-15.07.2020
J. F. Hess, M. Kotrová, S. Calabrese, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. Paust
Automated library preparation for next generation sequencing of immunoglobulin gene rearrangements by centrifugal microfluidics
2020 MicroTAS 2020, 04.-09.10.2020, virtual
F. Schlenker, E. Kipf, N. Borst, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, P. Juelg
Centrifugal microfluidic 4 Plex digital droplet PCR for quantification of circulating tumor DNA
2020 MicroTAS 2020, 04.-09.10.2020, virtual
M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, K. Mitsakakis
RespiDisk: A Point-of-Care platform for fully automated detection of respiratory tract infection pathogens in clinical samples
2020 MicroTAS 2020, 04.-09.10.2020, virtual

2019

B. Johannsen, L. Müller, D. Baumgartner, L. Karkossa, S. M. Früh, N. Bostanci, M. Karpíšek, R. Zengerle, N. Paust, K. Mitsakakis
Automated pre-analytic processing of whole saliva on a centrifugal microfluidic platform for protein biomarker analysis
2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland
F. Schlenker, E. Kipf, S. Jenne, N. Borst, J. Lüddecke, K. Dormanns, T. Hutzenlaub, J. Steinert, N. Paust, R. Zengerle, F. von Stetten, P. Juelg
Doubling the order of color-multiplexing by photobleaching in Mediator Probe droplet digital PCR
2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17. 05. 2019
D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Flow profile through exposed porous media in centrifugal microfluidics
2019 MicroTAS, 27. – 31. October 2019, Basel/Switzerland
P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Baensch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. Hutzenlaub
Individual Response Monitoring Assay (IRMA) – Standardization Of Personalized Multiplex Biomarker Quantification
2019 EACR-ESMO Joint Conference on Liquid Biopsies, Bergamo/Italien, 15. – 17.05. 2019
S. Burger, L. Drechsel, A. Homann, F. von Stetten, R. Zengerle, N. Paust
LabSlice XL – A centrifugal microfluidic cartridge for the automated bio-chemical processing of industrial process water
2019 Transducers, Berlin, 23. - 27. 06. 2019
M. Specht, J. Schemberg, T. Förster, S. Burger, M. Rombach, N. Paust, R. Zengerle, F. von Stetten, G. Gastrock, M. Karle
Microfluidic App for centrifugal separation and purification of lymphatic cancer cells from whole blood
2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin
S. Hin, N. Paust, M. Rombach, J. Lueddecke, M. Specht, R. Zengerle, K. Mitsakakis
Minimizing ethanol carry-over in centrifugal microfluidic nucleic acid extraction by advanced bead handling and management of diffusive mass transfer
2019 Transducers 2019 - EUROSENSORS XXXIII, 23.-27. Juni 2019 - Berlin, Germany
KurzfassungWe present three concepts for centrifugal microfluidics reducing ethanol carry-over in magnetic bead-based nucleic acid (NA) extraction. Ethanol carry-over is critical regarding inhibition of downstream NA amplification. We identified two possible carry-over pathways: Liquid co-transport within bead-clusters and vapor diffusion. For the first time, we integrated magnetic bead handling in centrifugal microfluidics at continuous rotation aiming to avoid liquid co-transport within bead-clusters. Consequently, no significant contribution to ethanol carry-over could be assigned anymore to liquid cotransport. Major carry-over was attributed to diffusive transport of ethanol vapor. Countermeasures reduced this from 9.7 % (v/v) to 0.4 % (v/v), below the critical level for inhibition of downstream amplification reactions.
P. Juelg, M. Specht, M. Meyer, E. Kipf, F. Schlenker, F. Bänsch, S. Neumann, F. von Stetten, R. Zengerle, N. Paust, M. Fillies, R. Kirschner-Schwabe, S. Groeneveld-Krentz, M. Lehnert, C. Eckert, T. Hutzenlaub
Standardization of Personalized Multiplex Biomarker Quantification: Individual Response Monitoring Assay (IRMA)
2019 MST-Kongress, 28. - 30.Oktober 2019, Berlin
S. M. Früh, D. M. Kainz, T. Hutzenlaub, R. Zengerle, N. Paust
Tailor-made immunological reactions in lateral flow strips enables by total flow control
2019 Wissenschaftsforum Chemie, Aachen, 15. -18.09.2019
A. Brunauer, B. Breiner, D. Kainz, R. Verboket, F. von Stetten, R. Zengerle, N. Paust, T. Hutzenlaub, S. M. Früh
Towards digital diagnostic devices - From smart membrane cartridges to highly integrated test stripes
2019 Diagnostics-4-Future, 27. – 28. 11. 2019, Konstanz

2018

P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. Hutzenlaub
Automation of qPCR based Minimal Residual Disease Monitoring by Centrifugal Microfluidics
2018 11th Symposium on minimal residual cancer, 03. – 05.05.2018, Montpellier, Frankreich
J. F. Hess, S. Yazar, N. Paust, R. Zengerle, T. Hutzenlaub
Capillary Valve for Microfluidic Foil Chips Fabricated by Micro-Milled Metal Master Tools
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
N. Paust
Centrifugal Microfluidics:Unique operations enabled by artificial buoyancy
2018 Lab-on-a-Chip and Microfluidics Europe 2018, Rotterdam/Niederlande, 05. - 06.06.2018
S. Hin, B. Lopez-Jimena, M.A. Bakheit, V. Klein, S. Stack, C. Fall, A.A. Sall, K. Enan, S. Frischmann, L. Gillies, M. Weidmann, S. Goethel, V. Rusu, O. Strohmeier, N. Paust, R. Zengerle, K. Mitsakakis
Differential diagnosis of fever in West- and East-Africa
2018 WHO Geneva Health Forum, 10. – 12.04.2018, Genf / Schweiz
M. Schulz, N. Borst, M. Specht, S. Calabrese, F. von Stetten, R. Zengerle, N. Paust
From nasal swab to digital answer: unit operations for antibiotic resistance screening on a single cell level
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, R. Zengerle, T. Hutzenlaub
LabDisk for fully automated quantification of two leukemia associated gene targets
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
T. A. Kohl, M. Beutler, M. Merker, T. Paprotka, K. Rönsch, M. Schmitt, W. Grasse, C. Metzger-Boddien, K. Dormanns, J. Lüddecke, N. Paust, J. Schlanderer, L. Delamotte, J. Schickedanz, M. Steinwand, S. Niemann, H. Hoffmann
TB-SeqDisK: A microfluidics platform in combination with next generation sequencing for ultra-fast notification of Mycobacterium tuberculosis and its resistance pattern
2018 39th Annual Congress of European Society of Mycobacteriology, Dresden, 01. – 04.07.2018
D. Kainz, S. M. Früh, T. Hutzenlaub, R. Zengerle, N. Paust
Total flow control for lateral flow tests with centrifugal microfluidics
2018 MicroTAS 2018, 11. -15. November 2018, Kaohsiung / Taiwan
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, N. Paust, F. von Stetten, R. Zengerle, T. Hutzenlaub
Towards Standardization of Molecular Diagnostic Workflows: Centrifugal Microfluidic Automation of qPCR for Cancer Monitoring
2018 6th International Molecular Diagnostics Europe, Lissabon / Portugal, 22. - 24. 05.2018

2017

Y. Zhao, V. Klein, K. Mitsakakis, G. Czilwik, R. Zengerle, N. Paust
Automated particle based C-reactive protein immunoassay with on-disk pre-stored reagents and centrifugo-pneumatic liquid control
2017 MST Kongress, München, 23. - 25.10.2017
KurzfassungRapid and highly sensitive immunoassays can be achieved using microparticles due to the large surface to volume ratio. Such assays automated in centrifugal microfluidics show great potential for point-of-care application. We present a fully automated centrifugal microfluidic concept for implementing particle based immunoassay. With all reagents pre-stored on a LabDisk, the automation is controlled exclusively by the spinning frequency and does not require any additional means.
P. Juelg, M. Specht, E. Kipf, M. Lehnert, C. Eckert, S. Wadle, M. Keller, N. Paust, R. Zengerle, T. Hutzenlaub
Centrifugal microfluidic automation of dilution series for high dynamic range assays demonstrated for decadal dilutions up to 1:100,000
2017 MicroTAS 2017, Savannah /USA, 22.-26.10.2017
KurzfassungFor the first time we present the centrifugal microfluidic automation of an extensive dilution series that can cover all biochemically relevant dilution ranges. In contrast to existing methods, the new concept is based on iteration loops of individual dilution steps that can be easily combined in a theoretically unlimited fashion. Thus, any combination and range of dilutions can be implemented. The concept was demonstrated by generating a qPCR standard curve for cancer biomarker ETV6-RUNX1 up to 1:100,000. We achieved the following analytical performance characteristics: A high coefficient of determination of R²=98.9 %, equidistant quantification cycles of ΔCq=3.4±0.3 and low replicate variation coefficients of CV<3.5 %.
B. Johannsen, R. Zengerle, N. Paust
Disk-integrated repeated dispensing of 200 nl volumes for the automation of pyrosequencing
2017 MicroTAS 2017, Savannah /USA, 22.-26.10.2017
KurzfassungFor the first time, we present a proof-of-concept of disk-integrated automation of pyrosequencing. In contrast to existing methods-[1][2], our presented workflow doesn’t require any external dispensers for adding the nucleotides (dNTPs): instead, centrifugo-pneumatic timing, metering, and valving is employed to repeatedly dose-200 nl-dNTP solution from four different disk-integrated reservoirs in any user-defined sequence. First results of a seven-time repeated usage of all four dispensers show a maximum volume deviation of 9% to target volume. Preliminary sequencing results demonstrate the successful detection of the subsequent integration of thymine and adenine. The new automation concept enables a fully closed sequencing system, which is attractive for a potential use at the point-of-care (PoC).
F. Schuler, N. Borst, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, T. Hutzenlaub, N. Paust, R. Zengerle, F. v. Stetten
Eine Technologieplattform für die digitale Nukleinsäurediagnostik vor Ort (A Technology Platform for Digital Nucleic Acid Diagnostics at the Point of Care)
2017 3. Münchner Point-of-Care-Testing Symposium der DGKL (Deutsche Gesellschaft für Klinische Chemie und Laboratoriumsmedizin e.V.) 13. – 15. März 2017, München
N. Borst, M. Specht, M. Schulz, N. Paust, J. Li, S. Wadle, U. Götz, E. Held-Föhn, A. Heiß, F. Hausladen, R. Mader, K. Stock, M. Röder, A. Serr, G. Häcker, R. Zengerle, F. von Stetten
Integriertes System zur simultanen Detektion von Krankenhauskeimen und deren Antibiotikaresistenzen auf Einzelzellebene
2017 MST Kongress, München, 23. - 25.10.2017
KurzfassungBei Krankenhausinfektionen mit mehreren beteiligten Erregern ist die Zuordnung von Antibiotikaresistenzen zu den Erregern besonders wichtig um eine spezifische Therapie zu ermöglichen. Ein Projektkonsortium aus 6 Instituten der Innovationsallianz Baden Württemberg entwickelt im Projekt IDAK ein integriertes System das es künftig ermöglichen soll auf Einzelzellebene simultan die Spezies und die Resistenz aller Erreger in einer Probe zu bestimmen. Wir berichten von den aktuellen Forschungsarbeiten und ersten Ergebnissen. Diese umfassen: Entwicklung eines mikrofluidischen Testträgers zur Integration aller Prozessschritte; Überführung einzelner Bakterien eines Nasalabstriches in Tröpfchen; Bakterienlyse; digitaler multiplex-DNA Nachweis auf Basis einer isothermen Amplifikation; Multispektrale Fluoreszenzdetektion der Genotypen.
S. Burger, J. Schemberg, T. Förster, M. Specht, M. Rombach, N. Paust, R. Zengerle, M. Karle
Separation of low-abundance cells as an App on standard laboratory centrifuge
2017 MicroTAS 2017, Savannah /USA, 22.-26.10.2017
KurzfassungA novel centrifugal microfluidic cell separation module is presented to extract target cells (KG-1) from buffy coat using antibody coated microbeads. All structures required for the target cell separation are monolithically integrated in the microfluidic cartridge including mixing under constant rotation using oxygen bubbles. Thus, the microfluidic cartridge processing can be done on a standard laboratory centrifuge lowering the monetary investment for the user. The entire process chain of the module is completed within 26 minutes and recovers approximately 90 % of the lympathic cells in the sample while only requiring few manual pipetting steps.
S. Hin, B. Lopez-Jimena, M. Bakheit, V. Klein, S. Stack, C. Fall, A. Sall, K. Enan, S. Frischmann, L. Gillies, M. Weidmann, S. Goethel, V. Rusu, O. Strohmeier, N. Paust, R. Zengerle, K. Mitsakakis
The FeverDisk: Multiplex detection of fever-causing pathogens for rapid diagnosis of tropical diseases
2017 MicroTAS 2017, Savannah /USA, 22.-26.10.2017
KurzfassungWe report the successful implementation of twelve assays for detecting a diverse panel of fever-causing pathogens based on a centrifugal microfluidic LabDisk platform (FeverDisk). The target panel was selected to diagnose tropical regions’ most prevalent endemic and epidemic fever-causing diseases. The FeverDisk was used by local scientific staff in two clinical settings (Dakar, Senegal & Khartoum, Sudan). It was able to detect single and double infections from real patient samples in less than 2 h without any user intervention. The FeverDisk may provide an important solution for differential diagnosis in cases of fever of unknown origin thus improving accurate diagnostics and reducing the burden of pathogen drug resistance.
M. Rombach, M. Keller, N. Paust, F. von Stetten, D. Mark, R. Zengerle, M. Karle
The LabCard – A new approach for centrifugal assay automation
2017 MST Kongress, München, 23. - 25.10.2017
KurzfassungWe present the LabCard, a new centrifugal microfluidic approach for simultaneous processing of multiple test carriers by arranging them in the vertical plane. As a proof-of-concept, we fluidically integrated an assay for isothermal nucleic acid analyses of respiratory pathogens with the microfluidic network comprising unit operations and processing chains[1] for thermal lysis of a patient sample (25–75 μL), release of pre-stored reagents, mixing of reagents, aliquoting and distribution into amplification wells, which was successfully demonstrated in 5/5 runs with an overall fluidic processing time of 10 min.

2016

S. Hin, N. Paust, M. Keller, O. Strohmeier, R. Zengerle, K. Mitsakakis
A novel approach for dead-volume-free rehydration and mixing of dry pre-stored reagents in non-terminal chambers on centrifugal microfluidic platforms
2016 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, µTAS 2016, Dublin / Irland, 09. – 13.10.2016
F. Schuler, C. Siber, S. Hin, S. Wadle, N. Paust, R. Zengerle, F. von Stetten
Digital droplet loop-mediated isothermal amplification (ddLAMP) on a microscope slide
2016 Biosensors 2016, Goeteborg, 25. - 27.05.2016
I. Schwarz, D. Kosse, F. Schwemmer, R. Zengerle, N. Paust
Parallel robust hydraulic resistance aliquoting for equal reaction conditions on the centrifugal microfluidic platform
2016 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, µTAS 2016, Dublin / Irland, 09. – 13.10.2016
M. Rombach, M. Keller, N. Paust, F. von Stetten, D. Mark, R. Zengerle, M. Karle
The LabCard – A new approach for centrifugal assay automation”
2016 20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, µTAS 2016, Dublin / Irland, 09. – 13.10.2016

2015

F. Schuler, M. Trotter, S. Wadle, F. Schwemmer, R. Zengerle, F. von Stetten, N. Paust
Centrifugal microfluidic step emulsification for digital droplet recombinase polymerase amplification
2015 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences October 25-29, 2015, Gyeongju, KOREA
KurzfassungFor the first time we show centrifugal step emulsification. It enables the fast and easy production of monodispers w/o droplets with minimal handling effort (3 pipetting steps). In contrast to previously presented centrifugal emulsification systems [1], homogenous droplets with pre-selectable diameters were generated with zero run-in time and zero dead volume. The centrifugal microfluidic step emulsification was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). Compared to digital droplet PCR, the amplification time was reduced by a factor of 4 from 2 hours to 30 minutes.
M. Rombach, S. Zehnle, N. Paust, M. Weil, Ö. Sogukpinar, R. Zengerle, M. Karle
Microfluidic App for buffy coat extraction from large peripheral blood samples for low-abundance living-cell analysis
2015 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences October 25-29, 2015, Gyeongju, KOREA
L. Zielke, R. Moroni, T. Hutzenlaub, D.R. Wheeler, I. Manke, T. Arlt, N. Paust, R. Zengerle, S. Thiele
Modeling the missing carbon phase in X-ray tomographic reconstructions of a metal-based battery cathode
2015 ModVal, 12th Symposium on Fuel Cell and Battery Modeling and Experimental Validation. Munzingen (Germany), 26. - 27.03.2015

2014

R. Zengerle, D. Mark, N. Paust, F. von Stetten
Advanced centrifugal microfluidics and Microfluidic Apps
2014 EMBL Conference Series Microfluidics, Heidelberg, 23. - 25.07.2014
Y. Zhao, F. Schwemmer, S. Zehnle, F. von Stetten, R. Zengerle, N. Paust
Centrifugo-pneumatic handling of microparticles without external actuation as a new unit operation for centrifugal microfluidics
2014 MicroTAS 2014, San Antonio, USA, 26. – 30.10.2014 , Seiten: 21 - 23
KurzfassungFor the first time we present a microfluidic method for handling of microparticles that requires neither surface treatment of chambers and channels nor external actuators such as magnets. Thus it is not limited to handling of magnetic particles. Using centrifugal forces and temporary storage of pneumatic energy, only, we demonstrate 1) liquid mediated microparticle loading, 2) re-suspension of microparticles by shake mode at low centrifugation; sedimentation of microparticles and afterwards exchange of liquids with particle loss below 2% and supernatant removal efficiency of more than 99.5%, 3) re-suspension and subsequent transport of microparticles together with liquid reagent with particle loss of 6% or less.
L. Zielke, T. Hutzenlaub, D. R. Wheeler, I. Manke, T. Arlt, N. Paust, R. Zengerle, S. Thiele
Combining X-ray tomography with virtual design in LiCoO2 electrodes
2014 Gordon Research Seminar Batteries, Ventura/CA March 09.-14.03.2014
N. Paust, A. R. Fiebach, L. Drechsel, S. Zhang, R. Zengerle, F. von Stetten
LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
2014 IFCC WorldLab Istanbul, 22.-26-06-2014, Istanbul, Türkei
KurzfassungThe “LabTube” is a novel centrifugal lab-on-a-chip platform that uses a standard laboratory centrifuge as processing device. It automates multistep protocols such as nucleic acid extraction or protein purification, decreasing the hands-on-time from > 6 to 1 minute per extraction. Future applications will include point-ofcare sample-to-answer nucleic acid analysis. The LabTube approach lowers the market entry barrier for microfluidics as the user only requires to purchase disposable parts without the need to invest in specialized processing devices.
F. von Stetten, A. Kloke, A.R. Fiebach, J. Steigert, M. Hoehl, R. Zengerle, N. Paust
LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
2014 Biosensors 2014, Melbourne, Australia, 27.05.2014 – 30.05.2014
I. Schwarz, S. Zehnle, G. Czilwik, T. Hutzenlaub, F. von Stetten, D. Mark, R. Zengerle, N. Paust
Rapid development of centrifugal microfluidic assay automation by network-simulation based fluidic design
2014 Biosensors 2014, Melbourne, Australia, 27.05.2014 – 30.05.2014

2013

G. Czilwik, O. Strohmeier, I. Schwarz, N. Paust, S. Zehnle, F. von Stetten, R. Zengerle, D. Mark
An integrated Lab-on-a-Chip system with DNA extraction, pre- and main PCR amplification for automated detection of low concentrated pathogens
2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , Seiten: 1607 - 1609
L. Drechsel, M. Schulz, F. von Stetten, R. Zengerle, N. Paust
Automated on-site detection of organophosphorous pesticides in real food samples
2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , Seiten: 1923 - 1925
M. Hoehl, M. Weißert, N. Paust, R. Zengerle, A. H. Slocum, J. Steigert
Centrifugal LabTube for fully automated DNA extraction & lamp assay based on an integrated, low-cost heating system
2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , Seiten: 1276 - 1278
A. Kloke, S. Niekrawietz, A.R. Fiebach, J. Bernhardt, R. Kneusel, K. Schemel, J. Ritzel, F. von Stetten, R. Zengerle, N. Paust
Disposable LabTube cartridges for automated protein purification in standard lab centrifuges
2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , Seiten: 1628 - 1630
KurzfassungThe protein purification process is often the bottleneck for the efficient production of a large number of different proteins. Automation of these procedures is often the crux of the matter and is frequently a trade-off between efficiency and cost. Using our novel disposable LabTube cartridges we demonstrate how the process of His-tagged protein purification can be automated in standard laboratory centrifuges. LabTube cartridges include prestored reagents which are sequentially applied to a Ni-NTA purification matrix by an integrated ballpen mechanism actuated by acceleration changes of the centrifuge. Fully automated runs demonstrated similar yield and purity compared to manual purifications with sample addition as the only manual handling step. Thus, the user is available for parallel tasks during 95 % of the overall process time (33 min). In contrast manual processing requires the user to be present for 18 minutes out of the 33 minute overall process time. Since LabTube automation requires no investment in a special lab automation device, this platform lowers the market entry barrier for lab automation.
M. Keller, G. Czilwik, T. van Oordt, O. Strohmeier, J. Drexler, D. Mark, D. Kosse, N. Paust, R. Zengerle, F. von Stetten
LabDisk – novel centrifugal microfluidic unit operations for sample-to-answer analysis and Microfluidic Apps
2013 9. Jahrestagung des Arbeitskreises Mikrosysteme für Biotechnologie und Lifesciences e.V, Jena, 18. - 20.06.2013
A.R. Fiebach, S. Zhang, L. Drechsel, A. Kloke, N. Fritzemeier, D. Wulff, J. Steigert, R. Zengerle, F. von Stetten, N. Paust
LabTube – an innovative platform for assay automation in laboratory centrifuges
2013 Microsystemtechnik (MST) Kongress 2013, Aachen, 14. - 16.10.2013 , Seiten: 27 - 30
KurzfassungIn this paper we present the innovative LabTube platform: A fully automated, easy to handle and cost-effective system that automatizes diverse assays on standard laboratory centrifuges and thus offers a reasonable alternative to existing lab-on-a-chip systems. The LabTube has the size of a 50 ml centrifuge tube and is composed of three stacked revolvers that are operated by a centrifuge-triggered ball-pen mechanism. The upper revolver provides the reagent pre-storage, the middle revolver comprises the assay-specific fluidic unit operations and the lower revolver functions as a unit for the collection and separation of the processed reagents. To demonstrate the functionality of the LabTube on the basis of a frequently used assay, a DNA extraction was performed. The fully automated DNA extraction from rapeseed lysate in the LabTube resulted in a DNA yield of 17,7 +/- 8,1 ng μl -1 in comparison to a manual reference with 14,8 +/- 1,5 ng μl -1. Thus, the hands-on time was reduced from 15 minutes to 1 minute by employing the LabTube, without the need for special training or special laboratory equipment. Currently, the LabTube is also under investigation for protein analysis and for point-of-care diagnostic.
J. Liebeskind, A. Kloke, A. R. Fiebach, F. von Stetten, R. Zengerle, N. Paust
Mixing by on-chip generated gas bubbles for assay automation in standard laboratory centrifuges
2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , Seiten: 967 - 969
A. Kloke, L. Drechsel, S. Zhang, A.R. Fiebach, N. Paust, R. Zengerle, F. von Stetten
The LabTube Platform – Disposable Cartridges For Automated Processing Of Biochemical Assays In Standard Laboratory Centrifuges
2013 21st annual international BIODETECTION TECHNOLOGIES, Washington, DC, USA, 18-19.6. 2013
KurzfassungA laboratory centrifuge can be applied to automate biochemical assays for point-of-care diagnostics or sample preparation such as DNA or protein extraction. Key innovation is integration of liquid handling into a 50 ml centrifuge tube. This "LabTube" harbors three revolvers which are stepwise rotated against each other by a g-force operated ball pen mechanics. The first revolver sequentially releases pre-stored reagents into the second revolver which is equipped with a mixing chamber and a solid phase column. Fractions of processed liquids are collected by the third revolver. Automated LabTube based DNA-extractions showed comparable yields to manual reference extractions.

2012

D. Mark, T. van Oordt, O. Strohmeier, G. Roth, N. Paust, D. Kosse, J. Drexler, M. Eberhard, F. von Stetten, R. Zengerle
A Functional Blister-Pack LabDisk System for Point of Care Testing
2012 Forum Biotechnologie Baden-Württemberg 19. September 2012, Freiburg
T. van Oordt, O. Strohmeier, D. Mark, D. Kosse, G. Roth, K. Achazi, P. Patel, S. Linke, N. Paust, M. Weidmann, J. Drexler, F. Hufert, R. Zengerle, M. Eberhard, M. Niedrig, F. von Stetten
A Functional Blister-Pack LabDisk System for Point of Care Testing
2012 64th Annual Meeting of the German-Society-for-Hygiene-and-Microbiology (DGHM) Location: Hamburg, GERMANY Date: SEP 30-OCT 03, 2012 Int. J. of Med. Microbiol., Band: 302, Ergänzungsband: 1, Seite: 7-7
R. Zengerle, J. Hoffmann, G. Roth, O. Strohmeier, A. R. Fiebach, L. Drechsel, S. Zhang, A. Kloke, N. Paust, D. Mark, F. von Stetten
Microfluidic Apps on standard Lab-instruments
2012 MicroTAS, Okinawa, Japan, 28. Okt. - 01. Nov. 2012 , Seiten: 239 - 241
KurzfassungHere we promote a new way of thinking: Designing microfluidic chips that can be processed on standard instruments which are already present in typical laboratory setups. Those instruments could be standard lab centrifuges, real-time PCR cyclers or even second generation sequencers. We call this approach the Microfluidic App approach
S. Zehnle, M. Rombach, F. von Stetten, R. Zengerle, N. Paust
Microfluidic centrifugo-pneumatic siphon enables fast blood plasma extraction with high yield and purity
2012 MicroTAS 2012, Okinawa/Japan, 28.10. - 01.11.2012 , Seiten: 869 - 871
F. Schwemmer, S. Zehnle, N. Paust, C. Blanchet, M. Rössle, F. v. Stetten, R. Zengerle, D. Mark
SAXS-LabDisk: A centrifugal microfluidic screening platform for protein structure analysis
2012 MicroTAS 2012, Okinawa/Japan, 28.10. - 01.11.2012 , Seite: p186
F. Schwemmer, S. Zehnle, N. Paust, C. Blanchet, D. Svergun, F. v. Stetten, R. Zengerle, D. Mark, M. Rössle
SAXS-LabDisk: A centrifugal microfluidic screening platform for protein structure analysis
2012 SAS Conference, Sydney, Autralia, Nov. 18 - 23, 2012
KurzfassungA small angle x-ray scattering (SAXS) screening platform for protein structure analysis based on centrifugal microfluidics is presented. SAXS can be used to reconstruct low-resolution structures of macromolecules directly from solution scattering. This enables screening for conformational changes of proteins due to different environmental conditions. However, for state-of-the art techniques, consumption of the protein samples is still at least 6 µl per condition and the time per measurement is at best 3 min. In most cases this still renders multi-parameter screening impractical. We present a centrifugal microfluidic platform capable of decreasing both, time per measurement and consumed protein volumes in small angle scattering screenings by more than one order of magnitude. During an automated rotational protocol the presented compact disk prepares 20 different screening conditions for each protein using 2 µl protein solution, 3 µl buffer and 3 µl screening solution. The three input solutions are split into 40 nl aliquots, the aliquots are then combined at predefined ratios, mixed and can be measured on chip. Up to seven independent protein screenings can be performed on one chip. Protein solution (2 µl), screening reagent (3 µl) and buffer solution (3 µl) are pipetted in the disk. During an automated rotational protocol the liquids are split into 120 aliquots of 40 nl each. Then 6 of these aliquots are combined, respectively. This results in 20 mixtures of different predefined ratios. One disk has enough space for seven dilution matrices or 140 experiments, which can be performed on chip within a SAXS beamline. Including positioning within the beam, the expected time per measurement is less than 5 s. The SAXS-LabDisk will enable routine SAXS screening of minute protein volumes. The performance of the SAXS-LabDisk for protein structure determination will be evaluated at the beamline PETRA-III at EMBL Hamburg, Germany later this year.
F. Schwemmer, S. Zehnle, N. Paust, C. Blanchet, D. Svergun, F. von Stetten, R. Zengerle, D. Mark, M. Rössle
SAXS-LabDisk: A centrifugal microfluidic screening platform for protein structure analysis
2012 EMBL Conference Microfluidics 2012, Heidelberg, Germany, July 25-27 , Seite: 186
KurzfassungA small angle x-ray scattering (SAXS) screening platform for protein structure analysis based on centrifugal microfluidics is presented. SAXS can be used to reconstruct low-resolution structures of macromolecules directly from solution scattering. This enables screening for conformational changes of proteins due to different environmental conditions. However, for state-of-the art techniques, consumption of the protein samples is still at least 6 µl per condition and the time per measurement is at best 3 min. In most cases this still renders multi-parameter screening impractical. We present a centrifugal microfluidic platform capable of decreasing both, time per measurement and consumed protein volumes in small angle scattering screenings by more than one order of magnitude. During an automated rotational protocol the presented compact disk prepares 20 different screening conditions for each protein using 2 µl protein solution, 3 µl buffer and 3 µl screening solution. The three input solutions are split into 40 nl aliquots, the aliquots are then combined at predefined ratios, mixed and can be measured on chip. Up to seven independent protein screenings can be performed on one chip. Protein solution (2 µl), screening reagent (3 µl) and buffer solution (3 µl) are pipetted in the disk. During an automated rotational protocol the liquids are split into 120 aliquots of 40 nl each. Then 6 of these aliquots are combined, respectively. This results in 20 mixtures of different predefined ratios. One disk has enough space for seven dilution matrices or 140 experiments, which can be performed on chip within a SAXS beamline. Including positioning within the beam, the expected time per measurement is less than 5 s. The SAXS-LabDisk will, for the first time, enable routine SAXS screening of minute protein volumes. The performance of the SAXS-LabDisk for protein structure determination will be evaluated at the beamline PETRA-III at EMBL Hamburg, Germany later this year.

2011

K. Mutschler, A. Ernst, N. Paust, R. Zengerle, P. Koltay
Capacitive detection of nanoliter droplets on the fly - investigation of electric field during droplet formation using CFD-simulation
2011 16th International Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 5-9 June 2011, Beijing China , Seiten: 430 - 433
KurzfassungRecently we presented a capacitive droplet sensor that enables the characterization of volume and velocity of dispensed nanoliter liquid droplets on the fly in a contact free manner [1]. In this work we perform a multi-physics simulation study to understand the physical effects behind the sensor signal. We combine a two-phase fluid dynamics model for droplet generation and droplet flight with an electrostatic model for analyzing the electric field distribution inside an open plate capacitor while the droplet is passing through. Beside droplet volume and velocity, also droplet tear-off point as well as droplet oscillations are reflected in the electric field distribution. The characteristic negative dip of the transient sensor signal which was observed in experiments can be explained by capacitive coupling of the liquid column with the sensor and is correctly reflected by the model. The detected changes in charge on the sensor capacitor, are in the range of 2 – 28 fC and correspond to droplet volumes in the range of 5 nl < Vdrop < 100 nl. This is in good agreement with experimental findings and analytical approximations.
M. Karle, G. Czilwik, J. Miwa, N. Paust, G. Roth, R. Zengerle, F. von Stetten
Continuous microfluidic DNA purification for online monitoring and process control
2011 Proceedings of 2011 International Conference on Microtechnologies in Medicine and Biology Lucerne, Switzerland, 4-6 May , Seiten: 197 - 198
KurzfassungWe demonstrate the first continuous microfluidic platform for flow-through DNA purification from cell lysate. Using superparamagnetic beads, DNA is continuously transported across interfaces between co-flowing laminar streams of extraction reagents. In on-chip experiments DNA was continuously purified over a time period of 110 min. After the on-chip purification, DNA content and purity of the eluate sampled at different stages of the continuous extraction experiment was analyzed off-chip via qPCR. Results show successful flow-through purification with constant output over almost the complete duration of the experiment. Possible applications are seen in biological safety and environmental monitoring or bioprocess control.
Fabian Stumpf, Junichi Miwa, Nils Paust, Felix von Stetten, Roland Zengerle, Günter Roth
Development of segmented-flow microfluidic operations for single-cell nucleic acid analysis
2011 45. Deutschen Gesellschaft für Biomedizinische Technik (DGBMT), September 27-30, Freiburg
KurzfassungThe importance of single cell analysis is rapidly growing especially in the fields of biological and medical research. A cost- and time-efficient technology for handling and analyzing individual cells instead of averaging whole culture popu-lations is extremely attractive for applications like drug development, pathological screening, cancer development and many others. Segmented-flow microfluidics is thought to be highly suitable for this purpose, considering the ability to handle a series of minute reaction compartments at moderate-to-high throughputs. Our on-going development of segmented-flow microfluidic devices aims for the realization of an integrated, automated single-cell nucleic acid analysis system with complete sample preparation capabilities. Although some of the required unit operations such as droplet mixing and thermocycling are already fairly established in this field, key procedures such as accurate single-cell encapsulation and nucleic acid purification are still missing.
Artur Tropmann, Nils Lass, Nils Paust, Christoph Ziegler, Roland Zengerle, Peter Koltay
Erzeugung monodisperser Mikropartikel aus wässrigen Lösungen Monodisperse Microparticle Generation from Aqueous Solutions
2011 Mikrosystemtechnik-Kongress, Darmstadt, Deutschland, October 10-12 , Seiten: 941 - 944
M. Karle, G. Czilwik, J. Miwa, N. Paust, G. Roth, R. Zengerle, F. von Stetten
Microfluidic flow-through DNA purification for continuous monitoring applications
2011 EuroMedLab Berlin 2011 – Berlin, 15-19 May 2011 Clin Chem Lab Med, Band: 49, Ergänzungsband: 1, Seiten: S607 - S607
A. Tropmann, N. Lass, N. Paust, C. Ziegler, R. Zengerle, P. Koltay
Monodisperse microparticle generation from aqueous solutions
2011 Proc. of 16th International Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 5-9 June 2011, Beijing China , Seiten: 1460 - 1463
KurzfassungWe present a new approach for the generation of monodispersed droplets and tailor-made microparticles of complex liquids from a star-shaped nozzle that precisely defines the dispensed droplet sizes. From two aqueous polymer solutions: 30w% Polyvinylpyrrolidone (PVP) (viscosity η ≈ 105 mPas) and 40w% PVP (η ≈ 490 mPas) droplet volumes of 3.9 nl and 3.2 nl respectively were generated employing a star-shaped silicon nozzle with a diameter of 183 μm. From 1w% Mannitol (η ≈ 1 mPas) droplets (100 pl) and particles (22 μm) were generated from a 59 μm nozzle. These results show for the first time particle generation with the StarJet method that could be applicable for the generation of monodispersed powders for use in healthcare, food and home care products.

2010

A. Yusof, L. Riegger, N. Paust, A. Ernst, R. Zengerle, P. Koltay
A Non-Invasive Single Cell Dispensing Approach for 2-Dimensional Micro-Patterning
2010 Actuator 2010, Bremen, Germany, 14.-16. June , Seiten: 1033 - 1036
KurzfassungWe present a computer vision-based approach for detection of micro-beads and cells combined with a noncontact liquid dispensing system to pattern single polystyrene-beads and yeast cells in a 2-dimensional array. A so called NanoJet dispenser for dispensing liquid borne particles features the average droplet volume of 150pL to 950pL and a reproducibility of (CV) < 3%. The computer vision set-up consists of a CCD camera coupled with a magnifying lens, which was employed to detect the micro-beads close to the dispenser’s orifice prior to dispensing. A real-time sequential image analysis was carried out by using a simple temporal differencing detection algorithm to identify single cells or particles in the proximity of the orifice that would be ejected with the subsequent dispense. Using this process arrays of polystyrene-beads and yeast cells were deposited onto glass slides attached to a programmable motorized stage. The overall deposition efficiency obtained was 70% with 58% of the spots contained single polystyrene-beads or cell respectively. Keywords: single-cell, computer vision based detection, non-contact droplet dispensing, cell printing
N. Wangler, M. Welsche, G. Roth, N. Paust, R. Zengerle
A disposable discrete-agent-release cartridge for flexible endoscopes
2010 Proc. of the 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS), Groningen, The Netherlands, October 3 – 10 , Seiten: 1205 - 1207
KurzfassungWe present a disposable four-channel-cartridge as a new tool for flexible endoscopes to release adjustable and precisely defined agent volumes. The agent volumes are generated by externally triggered (0 – 11 kHz) release of discrete droplets (Vdroplet = 8 pl) with flow rates up to 88 nl/s in each channel. The miniaturized cartridge (l × w × h = 9 mm × 1.2 mm × 1.4 mm) can be inserted into working channels of standard flexible endoscopes (Øworking channel = 2 – 3 mm). Up to four different agents are stored in separate integrated reservoirs (Vreservoir = 1 μl). Each channel is equipped with a bubble jet actuator which allows for addressing the single reagents individually. To prevent any diffusion based agent leakage a diffusion barrier is realized by forming a stable phase separation via capturing an air bubble in front of the dispenser’s nozzle orifices. KEYWORDS: multi channel discrete agent release, bubble jet actuator, minimal invasive surgery, phase gap
M. Karle, G. Czilwik, J. Miwa, N. Paust, G. Roth, R. Zengerle, F. von Stetten, Felix von Stetten
High-performance flow-through DNA purification on a microfluidic chip
2010 Proc. of the 14th International Conference on Miniaturized Systems for Chemistry and Life Sciences (MicroTAS), Groningen, The Netherlands, October 3 – 10 , Seiten: 106 - 108
KurzfassungWe present a significant increase in performance for flow-through purification of nucleic acids by continuous microfluidic processing. After binding to superparamagnetic beads the nucleic acids are sequentially transported across the phase-interface of co-flowing laminar streams of purification reagents. The entire purification procedure is performed within only 2 minutes. Compared to classical batch-wise purification in test tubes, 150  50 % of total DNA have been recovered in on-chip purifications over a DNA concentration range of 7 orders of magnitude. With appropriate surface modification of the magnetic beads the chip is also suggested for the implementation of other continuous biomolecular purification tasks. KEYWORDS: Nucleic Acids Purification, Magnetophoresis, Continuous Processing, Flow-Through Assay
T. Preis, D. Mark, N. Paust, C. Ziegler, G. Roth, R. Zengerle, F. v. Stetten
Lab-on-a-Chip Design- und Foundry-Service: Implementierung und Miniaturisierung biochemischer Assays auf Grundlage einer Bibliothek validierter mikrofluidischer Grundoperationen
2010 Tagungsband des 15. Heiligenstädter Kolloquiums , Seiten: 123 - 132
Phillip Kuhn, Nils Paust, Roland Zengerle, Felix von Stetten, Günter Roth
Smaller Structures Taking the Lead - Analysis and Simulation of Structure Size Influences on Binding Kinetics Down to the Single Molecule Level
2010 Proc. of IEEE-MEMS, Hong-Kong, China, January 24-28 , Seiten: 919 - 922
KurzfassungThis paper describes a method for the quantitative detection of biochemical binding events onto mi-crostructured and functional surfaces on a truly single molecular level. The classic Streptavidin-biotin system is used to provide the last detection step and the binding is visualized via gold-nanoparticles in a SEM. We showed that this allows a spatial resolution down to the nanometer scale. It also allowed us to proof the spot size dependence of binding kinetics according to the theorem of Ekins in one single experiment. The method allows to analyze any binding event on a planar surface and is enabling to measure surface densities of func-tional groups like the amount of BSA molecules on a blocked glass surface.

2009

N. Paust, S. Krumbholz, S. Munt, C. Müller, R. Zengerle, C. Ziegler, P. Koltay
Design of a passive and portable DMFC operating in all orientations
2009 Proc. IEEE-MEMS; 25 – 29 January 2009, Sorrento, Italy , Seiten: 1091 - 1094
KurzfassungA microfluidic layout concept for passive and portable Direct Methanol fuel Cells (DMFCs) is presented. We proofed this concept by developing a DMFC that continuously runs for 40 hours in all orientations without the need for any active components such as pumps or valves. In contrast to our previous work [1], the system now is truly portable. In any orientation of the DMFC, a bubble driven self regulating supply mechanism safely removes carbon dioxide and transports at least 3.5 times more methanol to the anode than critically needed to sustain DMFC operation. On the cathode, diffusive oxygen supply and the transport of the reaction product water along a capillary gradient out of the DMFC ensures a stable performance. Compared to our previous work [1], the power output was increased by a factor of 2.5 and reached p = 5.5 mW cm-2. A stable power output for 40 hours of p = 4 mW cm-2 was achieved for the preferred vertical position with bubbles moving against buoyancy forces. In the most challenging horizontal position with the anode facing downwards, a power output of at least p = 3.1 mW cm-2 was reached for the same period of time.
C. Ziegler, N. Paust, R. Zengerle
Micro two-phase transport in polymer electrolyte fuel cells
2009 Book of abstracts; 6th Symposium on Fuel Cell Modelling and Experimental Validation, German Aerospace Center (DLR), Bad Herrenalb / Karlsruhe , Seite: 67
KurzfassungMicro two-phase flow plays an important role for the operation of polymer electrolyte fuel cells. Hydrogen fuel cells (PEMFC) and direct methanol fuel cells (DMFC) are the most important types of polymer membrane fuel cells. At the cathode water is generated as a result of the oxygen reduction reaction in the PEMFC and DMFC. This leads to two-phase flow of gas and liquid water in the porous components (gas diffusion layer, catalyst layer) and channels of the fuel cell. Moreover in the DMFC carbon dioxide is generated and forms gas bubbles at the anode side. Through the complex coupling of the two-phase flow with the electrochemical reaction the performance and stability of the fuel cell are influenced by the transport on the micro-scale. We present modelling approaches that allow for the analysis of two-phase flow on the micro scale and derive engineering approaches for fuel cell components. Finally experiments are presented that show how the negative impact of the two-phase flow can be mitigated and even be turned into better system efficiency.
N. Wangler, M. Welsche, M. Laufer, A. Träger, N. Paust, M. Thielen, O. Sobolev, G. Roth, R. Zengerle, J. Steigert
Predictable and defined microgradients in liquid environment for chemical single cell stimulation
2009 Proc. of the Thirteenth International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS), Jeju, Korea, November 1-5 , Seiten: 679 - 681
KurzfassungWe present a new method for the precise and predictable generation of defined concentration spots in space and time within liquid environments via a discrete substance release in the sub pL-range (V = 10 pL) with a high spatial (< 50 μm) resolution to stimulate individual cells within densely populated cell cultures. A modular diffusion barrier (phase-gap) placed on the tip of the pL-dispenser (Pico-Injector) prevents of any diffusion based leakage. This allows for the positioning of the dispensing system at any position in a target liquid (e.g. next to an individual cell) to realize sharp and controlled concentration profiles predicted by analytical diffusion model. Dispensing individual droplets enables concentration profiles locally (c < 1/5⋅cmax outside a radius of r = 50 μm) and temporally (c < 1/5⋅cmax after 8 s) well defined. This setup was proven by labeling a single L 929 cell [1].

2008

Paust, Nils, Litterst, Christian, Metz, Tobias, Zengerle, Roland, Koltay, Peter
Fully passive degassing and fuel supply in direct methanol fuel cells
2008 Proc. IEEE-MEMS 2008, Tucson, USA , Seiten: 34 - 37
KurzfassungIn this paper a micro direct methanol fuel cell (μDMFC) is presented, which is operated in a completely passive way, i.e. the cell does not require an external pump for fuel supply. The surface energy of deformed CO2 bubbles, generated as a reaction product during DMFC operation, is employed to supply methanol to the anode. In contrast to a digital valve based approach presented earlier by Meng et. al. [1], a tapered channel is applied to achieve a pumping mechanism. This way the pump rates can be adapted to the requirements of a specific cell. The presented study reveals that this concept is able to maintain the supply for all typical DMFC operation conditions. Experimental results are presented that demonstrate the continuous operation of a passive μDMFC for more than 15 hours.

2007

Paust,N., Litterst,C., Metz,T., Eck,M., Zengerle,R., Koltay,P.
Capillary driven fuel supply in direct methanol fuel cells with double tapered t-shaped channel flow fields
2007 Proceedings of PowerMEMS, Freiburg, Germany, 28-29 November 2007 , Seiten: 185 - 188
Paust,N., Litterst,C., Metz,T., Zengerle,R., Koltay,P.
Gasblasengetriebene Pumpe für Mikroreaktoren
2007 MikroSystemTechnik Kongress, Dresden, Germany, 15.-12. Oktober 2007 Proceedings, VDE, Seiten: 481 - 484
Metz,T., Paust,N., Müller,C., Zengerle,R., Koltay,P.
Micro structured flow field for passive water management in miniaturized PEM fuel cells
2007 MEMS 2007, Kobe, Japan, 21-25 January 2007 Proceedings of the 20th IEEE International Conference on Micro Electro Mechanical Systems, MEMS
Metz,T., Paust,N., Müller,C., Zengerle,R., Koltay,P.
Mikrostrukturierte Gasverteilerstrukturen für den passiven Wasseraustrag aus PEM Brennstoffzellen
2007 MikroSystemTechnik Kongress, Dresden, Germany, 15.-12. Oktober 2007 Proceedings, VDE, Seiten: 913 - 916
Metz,T., Kerzenmacher,S., Paust,N., Mueller,C., Zengerle,R., Koltay,P.
Passive water management system for pem fuelcells using microstructures
2007 Proceedings of PowerMEMS 2007, Freiburg, Germany , Seiten: 177 - 180

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Publikationsliste Dr. Nils Paust

Originalarbeiten in wissenschaftlichen Fachzeitschriften

Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften

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