Piezoelectric MEMS Tilt Sensor

Abstract

This dissertation describes two piezoelectric micro-electro-mechanical (MEMS) resonant tilt sensors and report on the experimental evaluation of them. The sensors are fabricated using silicon on insulator (SOI) MEMS technology. Triple beam turning fork resonators with piezoelectric layer is applied for drive and sense elements for the acceleration. Axial force is applied to the turning forks by a proof mass which is 2.2mm x 1.7mm when the sensors are subjected to angular tilt. The resonant frequency at same magnitude but different direction will change according to the tensile and compressive force from two sides of the sensors. Analysis on finite element modeling is used to find its desired mode and resonant frequency. The resonance frequency of two sensors is 137Hz at the desired mode which is flexural mode. Sensor resolution is improved by a trans-impedance amplifier which have a gain of 40dB and bandwidth is 44MHz.The different between two sensors is that one apply first class micro levers to amplify the input force and one without micro levers.-90 to90 degree dynamic range for tilt measurement is demonstrated to test the sensitivity of the sensors. The sensitivity of the two sensor is 60Hz/g and 46Hz/g respectively.