A valve-less planar pump isotropically etched in silicon

The first valve-less diffuser fluid pump in silicon is presented. It consists of a planar double-chamber arrangement fabricated in a silicon wafer anodically bonded to a glass wafer. The pump uses fluid-directing diffuser-nozzle elements which have a depth of 24-48 mu m and a neck width of 88-104 mu m. The pump chamber diameter is 6 mm. Pump cavities and diffuser-nozzle elements are etched with an isotropic HNA silicon etch. Pumps with three different diffuser lengths are compared reaching a maximum pump capacity of 230 mu l min(-1) and a maximum pump pressure of 1.7 m H2O at a resonance frequency of 1318 Hz for methanol.