A novel micropump design with thick-film piezoelectric actuation

A new design for a silicon-based micropump is described. Passive cantilever valves are produced by boron etch stop and fusion bonding. Tests of these valves show good performance, as no flow could be detected in the reverse direction. Initial experiments on a thick-film screen printed piezoelectric membrane actuator were undertaken. A study of suitable inks for electrodes on different insulation layers on silicon yielded silicon dioxide and cermet gold ink as the most satisfactory combination. Deflection measurements of a 7 mm x 3 mm PZT (lead zirconate titanate)-8 mm x 4 mm Si bimorph membrane gave 1 mu m movement at an applied voltage of 100 V. A quasi-static simulation package of the flow through a micropump is also presented. The valve action is simulated using ANSYS coupled with FLOW3D. The piezoelectric membrane deflection is simulated with ANSYS. A differential equation for the combined actuation of membrane and valves is solved numerically with Maple. Pump rates of up to 900 mu l min(-1) and a maximum backpressure of up to 70 kPa for a driving voltage of 40 V have been modelled using bulk values for PZT-5H. A pump rate of up to 400 mu l min(-1) and a maximum backpressure of up to 35 kPa at 100 V driving voltage are predicted using thick-film parameters extracted from the measurements.