Microvalves with bistable buckled polymer diaphragms

A microvalve with a bistable buckled diaphragm has been developed which can be employed for microfluidic systems. The bistable diaphragm is used to open or close the inlet of the microvalve. There is no power consumption either in the closed or in the open state, and the valve is closed tight against an inlet gas pressure of up to 470 hPa. The case of the valve is made by molding in PMMA and joined to a polyimide diaphragm thick by adhesive bonding. The temperature treatment and mechanical loading during bonding, and the different thermal expansions of PMMA and polyimide, result in a compressive stress and in buckling of the diaphragm. The microvalve has an outer diameter of 5 mm and is 1 mm thick.