Enhanced Sensitivity and Stability of a Novel Resonant MEMS Electric Field Sensor Based on Closed-Loop Feedback

To improve the sensitivity and stability, a novel mode-localization resonant MEMS (Micro-Electro-Mechanical System) electric field sensor based on closed-loop feedback is presented in this paper. The sensor is based on the principle that the mode localization effect can dramatically increase the sensitivity of a resonant system. Moreover, in order to detect the electric field in real-time and improve the resolution and stability of the sensor, closed-loop feedback is introduced. One of the output signals of the sensor is fed back to the input port, where the output signal has been processed by a phase-locked loop part and automatic gain control part. This paper analyzes amplitude-frequency characteristics, phase-frequency characteristics, sensitivity, and output characteristics by modeling, theoretical calculation, and finite element simulation. The device prototype is fabricated based on SOI process. Tested in vacuum conditions, the minimum detectable electrostatic field of the sensor is better than 10V/m, the accuracy of the sensor is 5.3%, and the repeatability is 0.56%.