Media protected surface micromachined leverage beam pressuresensor

Abstract

In this paper we present the first surface micromachinedultraminiaturized, highly sensitive, pressure sensor that utilizes aforce-transducing beam and a 2 µm thick polysilicon pressure sensingdiaphragm as an encapsulation layer for high media isolation of thesensing piezoresistor. A beam is attached to the diaphragm at one end andto the cavity at the other end. The pressure-induced diaphragm deflectionis transduced to strain in the beam and sensed by a piezoresistivestrain-gauge on the beam. The piezoresistor is thus well isolated from thesensing environment. The pressure sensing performance was measured to0.9 µV V-1 mmHg-1.