A MEMS Resonant Accelerometer With High Relative Sensitivity Based on Sensing Scheme of Electrostatically Induced Stiffness Perturbation

Abstract

This paper reports a micro electromechanical system (MEMS) resonant accelerometer with high relative sensitivity based on sensing scheme of electrostatically-induced stiffness perturbation for the first time. The perturbation electrodes convert the acceleration induced displacement of proof masses to electrostatic perturbation force and cause the effective stiffness perturbation and frequency shift of the resonator. The design of structure dimensions and the application of electrostatically-induced stiffness perturbation lower the resonant frequency and improve the sensitivity, resulting in the improvement of relative sensitivity. The sensing scheme is theoretically analyzed and the device is systematically simulated by finite element analysis (FEA). The open-loop characterization demonstrates that the differential sensitivity is 297.5 Hz/g at resonant frequency of 16.061 kHz under polarization voltage of 50 V. The relative sensitivity, defined as the absolute sensitivity divided by resonant frequency, of 1.8523 %/g is much higher than the traditional instability is 0.11 mg and noise floor is 13.2 mg/√Hz. The resonant accelerometers based on axial force sensing. The bias performance makes the device a potentially attractive option for highly-sensitive acceleration measurements.