Electrostatic charge sensor based on micro resonator with sensing scheme of effective stiffness perturbation

Abstract

A resonant electrostatic charge sensor with high sensitivity based on micro electromechanical system technology is proposed to measure electric charge. During measurement, input charge produces lateral electrostatic force to change effective stiffness of double-ended tuning forks resonator, and lead to a resonant frequency shift. The charge sensing functionality is experimentally verified and the sensitivity is found to be 4.4×10−4 Hz/fC2. We show that the proposed scheme has a higher sensitivity compared to the traditional axial strain modulation counterpart. The charge sensing scheme also introduces electrical coupling inside the device to create additional energy transmission path that improve quality factor. The resonant frequency stability associated with linear transduction and instability associated with mechanical nonlinearity are investigated.