Sensitivity Enhancement of Thermal Piezoresistive Resonant MEMS Sensors Using Mechanical Coupling and DC Tuning

In this work, we present a Silicon on Insulator (SOI) mechanically coupled MEMS device composed of three rotating ring resonators for enhancing its sensitivity. It shows the exploration of Thermal Piezoresistive (TPR) transduction in mechanically coupled ring resonators for mass sensing applications. Mass sensing experiments are performed by dropping the silver nano drops on the surface of the resonator. It includes the first-time investigation of a three degree of freedom (3-DOF) differential ring-shaped TPR (DR-TPR) MEMS coupled-resonator and involves the selection of the best configuration of the differential drive and sense scheme that enhances the signal-to-noise ratio (SNR) using feedthrough cancellation. Amplitude change and amplitude ratio offer an enhancement in normalized sensitivity by 92 and 131 times respectively along with the common-mode rejection in comparison to their frequency shift counterparts. This coupled-resonator can show a quality factor of more than 1300 in ambient conditions, facilitating the resolution and DC tunability improvement. This work paves the way to realize various sensors for ambient environment applications. [2022-0045]