Structure design and fabrication of a bistable microvalve

A bistable microvalve is presented in this paper. The microvalve is fabricated using a cheap and developing technology combined of micro-milling of a polymer, sputtering, photolithography and adhesive bonding. The bistable characteristic of a magnetic system compensates the high power consumption of thermopneumatic actuators. The initial gap height between the sealing membrane and the valve seat is optimized with respect to a large flow through the valve even at low inlet-outlet pressure difference and providing enough sealing force. Simulation results show that when the valve has an initial gap height of 70 µm, a gas flow can reach over 90% of the flow limit of the valve and the valve can theoretically seal a pressure difference of more than 5 bars. A prototype of the microvalve, which has a PMMA housing in dimensions of 26.0 mm × 26.0 mm × 10.9 mm, was fabricated. The valve can seal a gas flow of 350 kPa practically and the flow passes through the valve quite well even when the pressure difference is low. A gas flow of 490 Pa can generate continuous bubble flow when the tube connected to the outlet is put into water.