A NOVEL MICROPUMP DESIGN WITH THICK-FILM PIEZOELECTRIC ACTUATION

A new design for a silicon-based micropump is described. Passive canti lever valves are produced by boron etch stop and fusion bonding. Tests of these valves show good performance, as no flow could be detected i n the reverse direction. Initial experiments on a thick-film screen pr inted piezoelectric membrane actuator were undertaken. A study of suit able inks for electrodes on different insulation layers on silicon yie lded silicon dioxide and cermet gold ink as the most satisfactory comb ination. 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 a pplied 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 act uation of membrane and valves is solved numerically with Maple. Pump r ates 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 backp ressure of up to 35 kPa at 100 V driving voltage are predicted using t hick-film parameters extracted from the measurements.