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Electrohydrodynamic micropumps

: Richter, A.

Lenz, K. ; VDI/VDE Technologiezentrum Informationstechnik:
Actuator 90. Proceedings
Bremen, 1990
ISBN: 3-88132-905-6
International Technology-Transfer Congress <2, 1990, Bremen>
Conference Paper
Fraunhofer IFT; 2000 dem IZM eingegliedert
actuator; EHD; electrohydrodynamic; Elektrohydrodynamik; micromachining; micropump; Mikromechanik; Mikropumpe; Pumpe

Electrohydrodynamic (EHD) pumps offer the unique advantage that the electric forces act directly on the fluid throughout the entire pumping volume. Therefore, they require no moving parts as opposed to mechanical pumps, which have to use some kind of impeller or moving piston. With the new silicon micromachining technologies miniaturized EHD pumps based on different principles with high throughput and modest driving voltages can be realized. An EHD injection pump which consists mainly of two opposed grids, which are micromachined from single crystal silicon and bonded together anodically is presented. Pumping and static pressure generation was achieved with different polar fluids such as ethanole, propanole or acetone but most organic solvents and isolating oils can be pumped. With ethanole a maximum static pressure of 2.5 kPa (32 cm pumping head) and a pumping rate of 14 ml/min at a pressure of 420 Pa were achieved. For the realized pump the grid area measures 3 mm x 3 mm and the grid distance 350 mym. Pumping started at d. c. voltages as low as 40 V, wheras 700 V were needed for maximum throughput. To increase pressure several of the devices can be stacked. This opens up new applications like micromachined cooling systems or microhydraulic actuators. By further reducing the grid distance driving voltages below 100 V are expected.