Analysis and Testing of Charge Induction in a Resonant Torsional Electric Field Sensor Based on a 3-D Mechanical–Electrical Coupling Model

Microelectromechanical systems (MEMS) electric field sensors are extensively utilized in aerospace, meteorological observation, industrial production, and power system applications due to their advantageous characteristics, including small size, low power consumption, and suitability for mass production. This study investigated a resonant torsional MEMS electric field sensor to develop a 3-D mechanical–electrical coupling model, which addresses the limitations of traditional 2-D models in comprehensively reflecting the variation patterns of electrical parameters. Furthermore, the static mechanics and dynamics of the driving unit were analyzed, revealing the advantages of the sensor’s mirror-type double-torsion structural design; the resonance frequency and amplitude during operation were simulated, and the charge and current output characteristics of the sensing unit were quantitatively characterized. In addition, the incompatibility between the fabrication process and materials was resolved by optimizing the preparation method, thereby improving the overall yield of device fabrication. Furthermore, a frequency-doubling circuit was designed for weak signal detection, which enhances the stability and reliability of the measurement system. The sensor’s basic performance, including dynamic detection range, resolution, measurement uncertainty, and power consumption, was evaluated through the construction of a comprehensive experimental platform. Theoretical analysis revealed that applying a superimposed dc bias voltage can enhance the sensor’s amplitude, thereby improving its sensitivity, resolution, and other performance characteristics. Simulation results indicated that the charge-sensing efficiency and output current of the sensor can be enhanced by appropriately increasing the length, width, and number of sensing electrodes. Energy-dispersive spectroscopy (EDS) testing was conducted to verify the consistency between the device design and the fabrication process. Under industrial frequency electric field conditions, the sensor achieves a measurement range of up to 138 kV/m, with a sensitivity of 6.09 kV/m and a resolution of 3.9 V/m. Experimental results indicated that the electric field sensor achieved a resolution of 5 V/m within an electrostatic field range of 0100 kV/m, a linearity of 1.03%, and an uncertainty of less than 1.41% across three round-trip measurements. The power consumption of the sensor is measured to be only 128 mW. The proposed electric field sensor provides a solid foundation for future practical research in various applications.