A microvalve with a bistable buckled diaphragm has been developed whic
h can be employed for microfluidic systems. The bistable diaphragm is
used to open or close the inlet of the microvalve. There is no power c
onsumption 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 dia
phragm 25 mu m thick by adhesive bonding. The temperature treatment an
d mechanical loading during bonding, and the different thermal expansi
ons of PMMA and polyimide, result in a compressive stress and in buckl
ing of the diaphragm. The microvalve has an outer diameter of 5 mm and
is 1 mm thick.