Design and Simulation of Mems based Piezoelectric Acoustic sensor

A MEMS based acoustic sensor that combines high sensitivity, wide frequency range and low cost batch processed miniaturized silicon components to build self powered systems is presented in this paper. It also throws light on an effective method to monitor health of a machine which is by using an piezoelectric Mems microphone. The proposed Acoustic sensor consists of a sputtered piezoelectric ZnO layer that transforms the mechanical deflection of a thin-etched-Si diaphragm into a piezoelectric charge. This ZnO layer is sandwiched between bottom Al electrode and top Al electrode. The simulations of the proposed acoustic sensor is carried out for two designs i) The piezoelectric material being placed at the 4 corners of the silicon substrate and ii) The piezoelectric material being placed at centre of the silicon substrate. The thickness of the layers are chosen so as to withstand the dynamic sound pressure of 96-106db and it produces maximum of 8pV/Pa. The simulation is done by Comsol multiphysics and Coventorware.