On the selective mode excitation of wide tunable MEMS capacitive resonator

This research paper provides a simple and original approach to extend the resonant frequency tuning range for achieving high-to-low frequencies in electrostatically actuated microelectromechanical systems (MEMS) based resonators. In microstructures, low frequencies are usually achieved by increasing the effective mass or decreasing the mechanical stiffness. However, this work intends, assuming a double-sided electrodes design, to control the excited mode of the micro-system in order to achieve low frequencies through DC bias voltage variations and possibly eliminate the displacement dependency in capacitive micro-bridges-based structures. The design consists of a flexible microbeam where its equations of motion are derived within the framework of the nonlinear Euler–Bernoulli beam theory. The equations are then solved using the reduced-order modeling based on the Galerkin modal decomposition while considering the couple-stress theory. Simulation results show an improved performance of the proposed structure compared to previous studies. According to these results, a wide frequency tuning range has been achieved through a proper DC bias voltage arrangement. In addition, the outcomes of the numerical analysis were validated by comparing them with FEM results obtained by COMSOL software.