Tuning the Nonlinear Dynamics of Electrostatically Coupled Micromechanical Resonators to Enhance the Sensitivity of Mode-Localized Sensors

We demonstrate experimentally a nonlinear tuning mechanism enabling the sensitivity enhancement of mode-localized micromechanical sensors. First, the static pull in, eigenfrequency, and linear dynamics of the fabricated device are numerically calculated using finite element simulations to identify the operating dynamic range. Then, an open-loop experimental platform is established to test the fabricated device in a vacuum environment, and the experimental results show that the coupling voltage significantly affects the nonlinear behavior of the mode-localized resonators. Remarkably, the coupling voltage modifies the nonlinear dynamics of the proposed device with a transition in the frequency response from hardening to softening behavior for the out-of-phase mode. As a result, such a device can be used to detect the electric field strength, and the sensitivity depicted as the amplitude ratio per bias voltage can be enhanced up to 116% compared to fully hardening vibrations for both modes.