A novel micromachined pump based on thick-film piezoelectric actuation

A new silicon-based micropump is described in this paper. The key element of the device is a thick-film/silicon micromachined hybrid actuator. The actuation principle relies on the flexure of a screen printed piezoelectric lead zirconate titanate (PZT) layer on a silicon membrane (8 mm x 4 mm x 70 mu m) An investigation into the deposition technology of the bottom electrode for the piezoelectric material showed that a gold resinate or Pt evaporated electrode on a 500 nm thick SiO2 covered silicon wafer achieved best results for the membrane actuator. Inlet and outlet valves are of the cantilever type and use deep boron diffusion together with KOH etching. Pump rates of up to 120 mu l min(-1) have been achieved. A maximum backpressure of 2 kPa was measured when using a 600 V-pp sinusoidal drive voltage at 200 Hz across a 100 mu m thick PZT layer. The pump was compared with a conventional surface mounted piezoelectric driven micropump. The conventional pump achieves a performance which was a factor of 3-6 more efficient, but does not allow mass production. (C) 1998 Elsevier Science S.A. All rights reserved.