Three-Degree-of-Freedom Mode Localized Sensing within a Single MEMS Resonator Enabled by Two Parametric Modulation Signals

This paper reports the implementation of a three-degree-of-freedom (3-DoF) mode-localized sensing approach which, for the first time, utilizes coupled modes in a slotted double-ended tuning-fork (DETF) MEMS resonator by using two parametric modulation signals. Complex intra-modal virtual coupling and mode-veering behavior has been observed. This is utilized for mode-localized sensing, with amplitude ratio as the chosen output metric, when using a DC offset as a proxy for a physical stimulus induced stiffness perturbation. The proposed approach boasts 3 orders-of-magnitude greater sensitivity than the conventional frequency-shift based method. Also, the sensitivity can be tuned to improve the sensitivity by approximately 3.9-times. The proposed operating scheme shows promise as an alternative approach for realizing highly sensitive, highly tunable and smaller footprint mode-localized resonant sensors.