An electrohydrodynamic micropump

A micromachined electrohydrodynamic (EHD) injection pump is presented. The pump consists mainly of two opposed grids, which are micromachined from single crystal silicon and bonded together anodically. Pumping and static pressure generation is achieved with different polar fluids such as ethanol, propanol, or acetone, but most organic solvents can be pumped. With ethanol 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 are achieved. For the realized pump the grid area measures 3 mm×3 mm and the grid distance 350 μm. Pumping starts at DC voltages as low as 40 V, whereas 700 V are needed for maximum throughput. Pumping is also observed with an AC driving voltage. To increase pressure several of the devices can be stacked. The maximum flow rate and pressure head can be varied in a wide range by adjusting the dimensions of the pump. By further reducing the grid distance the driving voltages can be reduced