MEMS Electric Field Sensor with Comb-Actuated Resonant Torsional Shutter

This paper presents a MEMS electric field sensor featuring a comb-actuated resonant torsional shutter for DC electric field sensing. The sensor employs a torsional shutter driven by comb drives, with integrated starting electrodes on the fixed combs to initiate torsional oscillation. Compared to in-plane resonant shutters, the proposed torsional design enhances charge-sensing efficiency by modulating surface charges not only on the sidewalls but also on the top surface of the sensing electrode under a DC electric field. This increased modulation area results in improved sensitivity. In addition, the proposed architecture addresses fabrication challenges and structural limitations inherent to existing electrostatically driven torsional shutters with top-bottom electrodes actuation, particularly with respect to achieving large torsional displacement and bidirectional electric field detection. Experimental results demonstrate high linearity <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{R}^{2} &gt; 0.995)$</tex> and a sensitivity of 3.219 mV/(kV/m) over a wide DC electric field range of 0.833-250 kV/m, confirming the superior performance of the proposed sensor design.