Strain gauge pressure and volume-flow transducers made by thermoplastic molding and membrane transfer

Abstract

Strain gauge pressure and volume-flow transducers have been developed using the techniques of the so-called AMANDA process. It combines injection molding, surface micromachining, and membrane transfer and allows low-cost batch production of microfluidic devices. The strain gauges of the pressure transducer measure the deformation of a thin plate which is a linear function of the differential pressure. For temperature compensation, four strain gauges are arranged to a Wheatstone bridge, operated at constant supply voltage. Different designs cover the pressure range of up to 1 bar, the outer dimensions being 5.5/spl times/4.3/spl times/1.2 mm/sup 3/. A special design with an integrated capillary is used to measure volume flows.