Comsol models of two different microphones membrane with a piezoresistive sensing element

In this paper we present Finite Element (FEM) models for two different piezoresistive microphones, fabricated using the MultiMEMS process at SensoNor Technologies in Norway with an additional Deep Reactive Ion Etching step done at Sintef. We simulated the membrane displacement and the Eigen frequencies of the systems. Furthermore , we evaluated the stresses in the suspending beams in order to estimate the changes in resistances of the fours piezoresistors. The relative sensitivity of the Wheatstone bridge has also been found to be 0.44 mV/(VPa) for the thin membrane microphone and 1.4 mV/(VPa) for the thick membrane microphone.