Fig. 2: The experimental setup of the MEMS devices and frequency tracking system.

a, b Microscopic graph of the MEMS resonant accelerometer and the external readout resonator. The micromechanical resonant accelerometer consists of a proof mass, two DETFs and microlevers. The proof mass is placed in the center, with the microlevers and the DETFs symmetrically arrayed around. c Photograph of the testing PCB (printed circuit board) and packaged MEMS resonant accelerometer. The synchronized resonant accelerometer is composed of a three-stage PCB circuit, including an oscillation circuit, FPGA, STM microcontroller, and AD/DA converter. The sensing resonator and readout resonator are self-oscillated by their oscillation circuit, and the stable oscillating frequency is input to FPGA for high-precision frequency measurement. The frequency automatic tracking algorithm is written into the STM microcontroller and controls the output voltage of the AD/DA module