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.

No abstract

An electrostatically actuated polymer microvalve with a movable membrane electrode is presented. The microvalve cases are made by thermal injection molding of conductive polyamide. The movable membrane acting as an electrode consists of two insulating layers with a conductive layer in between. The three layers are patterned differently and transferred from a silicon wafer to the valve case in a batch process. The case of the microvalve and the three-layer membrane are joined by adhesive injected into cavities in the case. The three-layer membrane is moved electrostatically by a suitable voltage applied between the case and the membrane. The membrane of thickness is attracted to the upper or the lower valve chamber, thus opening or closing the inlet of the microvalve. The microvalve has an outer diameter of 5 mm and is 3 mm thick. The membrane electrode is moved when the voltage applied is approximately 60 - 150 V. Volume flows of up to 0.2 are attained at a differential pressure of 1100 hPa.

No abstract