Design of a tri-axial micro piezoelectric accelerometer

Abstract

A piezoelectric accelerometer based on bulk micromachining was presented in this paper. It is composed of a mass block and four cantilever beams with PZT piezoelectric thin films for detection deposited on cantilever beams. In order to realize the multi-axis detection with a single mass block, beam deformations due to the acceleration in X, Y, Z-axis directions were discussed to determine the corresponding connections of sensing elements. Analytical model was fundamentally derived and analyzed. Based on these, finite element method in ANSYS was used to design a tri-axial micro piezoelectric accelerometer. Parameters of the micro piezoelectric accelerometer, including the length, width and thickness of the cantilever beam and thickness of the PZT thin film, were optimized to acquire high charge sensitivity and wide bandwidth. Results showed that charge sensitivity along the X, Y, Z-axis could reach up to 23.85pC/g, 4.62 pC/g and 4.62pC/g, respectively, and the fundamental natural frequency up to 230.46Hz, for the presented micro piezoelectric accelerometer.