A novel micropump design with thick-film piezoelectric actuation

Abstract

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 mm PZT (lead zirconate titanate) - bimorph membrane gave 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 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 and a maximum backpressure of up to 35 kPa at 100 V driving voltage are predicted using thick-film parameters extracted from the measurements.

Current micropump technologies and their biomedical applications

“…The magnetic force ð F ! mag Þ between a current carrying wire and a permanent magnet can be expressed as: (Koch et al 1997) …”

“…Passive microvalves may only allow fluid to pass in one direction. The directional effect is a result from the motion of a mechanical opening/closing element, such as a cantilever (Koch et al 1997(Koch et al , 1998, membrane (Nguyen and Truong 2004) or ball or special flow directional geometry (nozzle/diffuser and Tesla).…”

06/00145 Valveless piezoelectric micropump for fueldelivery in direct methanol fuel cell (DMFC) devices

“…The earlier micropump design presented by M. Koch et al from UK utilized passive cantilever valves to control the fluid flow [36,37]. The pump actuator was fabricated by screen-printing a piezoelectric layer onto a silicon membrane (8 mm x 4mm x 70 m µ ).…”

“…Given that the material properties, dimensions and the applied voltage are known, this deflection is fully determined by Eqs. (31), (36) and (37). Here these equations are rewritten with the notations that will be used throughout the rest of the dissertation.…”

Photoresist patterned thick-film piezoelectric elements on silicon

“…Screen printed lead zirconate titanate (PZT) thick films have been used in numerous micro electromechanical systems (MEMS) applications such as micropumps [4,6,8], accelerometers [1] and resonant sensors [2]. The approach is attractive since it is a simple, low-cost process for depositing thick layers of piezoelectric material in the desired pattern.…”