Fabrication of a micropump for integrated chemical analyzing systems

Utilizing micromachining based on a semiconductor device fabrication technique, a miniature pump (micropump) was fabricated on a silicon substrate. The purpose is to integrate a conventional chemical analyzing system on an Si substrate by using microchemical sensors such as ISFET's and microvalves. The micropump was the diaphragm type. The pump was composed of an inlet and outlet having a one-way microvalve, a pressure chamber formed on an Si substrate and a miniature piezoactuator. The size of the pump was 8 mm × 10 mm × 10 mm and the flow rate on the order of μl/min could easily be controlled by the voltage signal applied to the actuator. To monitor the flow of the pump, a differential pressure sensor which could be formed on the Si substrate was developed. The sensor was composed of a one-way valve and a piezoresistive diaphragm-type pressure sensor, and had a high sensitivity to small flow.