Micropump manufactured by thermoplastic molding

Abstract

A micromembrane pump was manufactured by combined thermoplastic molding and membrane techniques. Pump cases were made of polyvinylidene fluoride (PVDF) and polysulfone (PSU). The mold insert was milled from a brass substrate. The lateral dimensions of the complete pump are 7 mm/spl times/10 mm. The depth and the diameter of the pump chamber are 100 /spl mu/m and 4 mm, respectively. The pump chamber is covered by a polyimide membrane 2.5 /spl mu/m thick. The inlet and outlet valves are integrated. The part of the membrane covering the pump chamber is corrugated to reduce the force needed for deflection of the membrane during pumping. The membrane is driven by an integrated thermopneumatic actuator. The air enclosed in an actuator chamber located on top of the membrane is heated by an electric current in a titanium wire. A micromembrane pump made of PSU was driven by short pulses (58 ms) of 15 V at a frequency of 5 Hz. The pump membrane was deflected 100 /spl mu/m towards the bottom of the pump chamber. The high compression ratio attained with the large membrane deflection allows gases to be pumped. A flow rate of 44 /spl mu/l/min and a differential pressure of 38 hPa was achieved. The average power consumption of the micropump was 0.45 W.