Publikationsliste Gerhard Birkle

• Originalarbeiten in wissenschaftlichen Fachzeitschriften
• Konferenzbeiträge

Originalarbeiten in wissenschaftlichen Fachzeitschriften

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2011

• M. Pospischil, K. Zengerle, J. Specht, G. Birkle, P. Koltay, R. Zengerle, A. Henning, M. Neidert, C. Mohr, F. Clement, D. Biro
  Investigations on Thick-Film-Paste Rheology for Dispensing Applications
  2011 Energy Procedia, Band: 8, Seiten: 449 - 454
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  Kurzfassung

  In order to establish dispensing as a promising metallization process in silicon photovoltaics, equipment and metal pastes require further optimization. By conducting several rheological experiments based on rotational tests, shear thinning as well as thixotropic behavior of thick-film pastes were investigated. Both are crucial parameters for continuous dispensing of 60 μm fingers with high aspect ratios. Flow rate fluctuations during dispensing though imply stress peaks that may disturb a continuous paste flow. Thus, a comparison of the flow rate of two pastes was conducted. A comparison of dispensed cells with screen-printed reference cells, on multi-crystalline wafer-material, showed an efficiency increase of 0.3%abs. on average. This is mainly caused by reduced finger widths and higher aspect ratios of dispensed fingers.

2005

• Jeyaprakash JDS, Steger R, Birkle G, Zengerle R, Koltay P, Ruehe J
  Modification of Micronozzle Surfaces Using Fluorinated Polymeric Nanofilms for Enhanced Dispensing of Polar and Nonpolar Fluids
  2005 Analytical Chemistry, Band: 77, Nummer: 19, Seiten: 6469 - 6474

2004

• Streule W, Lindemann T, Birkle G, Zengerle R, Koltay P
  PipeJet: A Simple Disposable Dispenser for the Nano- and Microliter Range
  2004 Journal of the Association for Laboratory Automation (JALA), Band: 9, Nummer: 5, Seiten: 300 - 306
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  Kurzfassung

  This paper reports on a simple, disposable non-contact dispenser for the nano- and microliter range. In contrast to other known dispensers manufactured by silicon micromachining the new device simply consists of an elastic polymer tube with a circular cross section. Actuation is done by a piezostack driven piston, squeezing the tube at a defined position near the open end by a significant fraction of the cross section. In contrast to drop-on-demand devices based on an acoustic actuation principle,5 the squeezing of the tube leads to a significant mechanical displacement of the liquid. Our experiments tested a large number of media in the viscosity range from 1 to 27 mPas. Some of our experiments tested up to approximately 2,000 mPas. Frequency characteristics showed an independent dosage volume for water up to a frequency of 15 Hz for tubes with an inner diameter of approximately 200 lm. Standard deviation within 1,000 shots resulted in an excellent CV (standard deviation/ dosage volume) of less than 2% of the dosage volume. Using tubes with an inner diameter of approximately 1,000 µm and a print frequency of 340 Hz, a flowrate of less than or equal to 143 µL/s could be reached. Beyond the possibility to dispense pure liquids, emulsion paints with particles that have a diameter of approximately 40 µm have also been printed successfully.

Konferenzbeiträge

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2009

• T. Metz, G. Birkle, R. Zengerle, P. Koltay
  StarJet: Pneumatic dispensing of nano- to picoliter droplets of liquid metal
  2009 Proc. IEEE-MEMS; 25 – 29 January 2009, Sorrento, Italy , Seiten: 43 - 46
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  Kurzfassung

  In this work we present a novel, simple and robust, pneumatically actuated dispenser for nano- to picoliter sized droplets of liquid metals. The so called StarJet dispenser utilizes a star-shaped nozzle geometry that stabilizes plugs of liquid in the centre of the nozzle by capillary force. This minimizes the wall contact of the liquid plug and reduces contact line friction. Individual droplets of liquid metal can be pneumatically generated by interplay of the sheathing gas flow in the outer grooves of the nozzle and the liquid metal. The working principle was first discovered and studied by Computational Fluid Dynamic (CFD) simulations. For experimental validation silicon chips with the star-shaped geometry were fabricated by Deep Reactive Ion Etching (DRIE) and assembled into a printhead. With different nozzle chips volumes between 120 pl and 3.6 nl could be generated at natural frequencies of 90 Hz and 400 Hz. The StarJet can either be operated as drop on demand or as continuous droplet dispenser. We printed columns of metal with 0,5 to 1,0 mm width and 40 mm height (aspect ratio >40) to demonstrate the directional stability of the ejection.
• Tobias Metz, Gerhard Birkle, Christoph Ziegler, Roland Zengerle, Peter Koltay
  StarJet: Pneumatische Erzeugung von Nano- bis Picoliter Tropfen flüssigen Lötzinns in einer sternförmigen Düse
  2009 Tagungsband Mikrosystemtechnik-Kongress, Berlin, 12.-14. Oktober , Seite: P 81
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  Kurzfassung

  In dieser Arbeit zeigen wir einen einfachen und robusten, pneumatisch aktuierten drop-on-demand Dispensierer (StarJet) zur Generierung von Tropfen flüssigen Lötzinns im Nano- bis Pikoliterbereich. Das System basiert auf einer sternförmigen Düsengeometrie, die das flüssige Metall im Zentrum der Düse durch Kapillarkräfte stabilisiert. Dabei ist der Wandkontakt und damit die Wandreibung zwischen dem Flüssigkeitstropfen und der Düse minimiert. Die sternförmige Geometrie ermöglicht in einem selbstorganisierten Wechselspiel mit der Strömung des Schutzgases (N2) in den Fingern des Sternprofils einen pneumatisch erzeugten Tropfenabriss. Dabei stellt sich bei konstanter Aktuation eine natürliche Eigenfrequenz der Tropfengenerierung ein. In Experimenten wurden Tropfen flüssigen Lötzinns, die beispielsweise für das Flip-Chip Bonding genutzt werden können, mit Volumen von 450 pl und 7.2 nl bei natürlichen Frequenzen zwischen 30 und 400 Hz erzeugt. Einzeltropfen konnten durch Aktuationszeiten im Bereich der Eigenfrequenz generiert werden. Durch kontinuierliche Aktuation konnten Säulen flüssigen Lötzinns mit einer Höhe bis zu 30mm bei einer Breite von 500µm erzeugt werden.

2004

• Lindemann T, Streule W, Birkle G, Zengerle R, Koltay P
  PipeJet™ – A Simple Disposable Dispenser for the Nanoliter Range
  2004 Bremen; Germany; 14-16 June Proceedings of Actuator 2004, Band: 1, Nummer: 1, Seiten: 224 - 227

2003

• Steger R, Bohl B, Moosmann C, Birkle G, Zengerle R, Koltay P
  A highly integrated nanoliter dispensing systemfor fast liquid handling
  2003 October 14-15, Munich, Germany Proc Micro.tec 2003, Seiten: 563 - 566

2002

• Steger R, Koltay P, Birkle G, Strobelt T, Sandmaier H, Zengerle R
  A Two-Dimensional Array of Piezostack Actuated Nanoliter Dispensers
  2002 8th International Conference on New Actuators, Bremen, Germany Proc. Actuator 2002, Seiten: 537 - 541
• Koltay P, Daub M, Steger R, Birkle G, Birkenmaier B, Zengerle R
  Miniaturized screening using a Dispensing Well Plate
  2002 San Diego, USA Proc High-Throughput Screening & Miniaturization Technologies (screentech)

2001

• Peter Koltay, Gerhard Birkle, Reinhard Steger, H. Kuhn, M. Mayer, Hermann Sandmaier, Roland, Zengerle
  Highly parallel and accurate nanoliter dispenser for High Throughput Synthesis of chemical compounds.
  2001 Proc International MEMS Workshop (I-MEMS) 2001 (Singapore, July 4-6, 2001); pp 115-124
• Peter Koltay, Reinhard Steger, Gerhard Birkle, Hsi-Che Huang, Hermann Sandmaier, Roland Zengerle
  Microdispenser array for highly parallel and aqccurate liquid handling.
  2001 SPIE’s International Symposium on Microelectronics and Micro-Electro-Mechanical Systems; (Adelaide, Australia; December 17-19, 2001)