Torque Sensing Device with Off-Center Anchored Resonant Sensing Suspension Beams

We report on the resonant torque-sensing silicon-oninsulator (SOI) device, where vibrating sensing elements simultaneously serve as elastic suspensions and a forceamplifying structure. Three double-clamped beams, making an angle of 120° to each other, are attached to a suspended ring at one of their ends and are anchored to the substrate with an offset from the ring's center of rotation. Torque applied to the ring induces axial stress in the beams, altering their frequencies. The stress is amplified due to a small inclination angle between the beams and the ring's geometric radius. The frequency sensitivity of 1.23 $\text{Hz} / \mu \text{rad}$, or alternatively, $7.50 \text{kHz} /(\text{nN} \cdot \mathrm{m})$ was registered in the experiments. Moreover, single-input-single-output (SISO) actuation and frequency sensing were demonstrated.