A selective excitation mode design for a wider high-to-low frequencies tunable capacitive MEMS resonator

This research paper offers a simple and original approach to extend the resonant frequency tuning range from high-to-low frequencies in electrostatically actuated microelectromechanical systems (MEMS) based resonators. Typically, it is possible to achieve low frequencies in MEMS through increasing the effective mass or decreasing the mechanical stiffness in micro structures. However, this work intends, assuming a double-sided electrodes design, to control the excited mode of the micro-system in order achieve low frequencies through DC bias voltage variations and possibly eliminating 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 and while considering the couple-stress theory. Simulations show an improved performance of the micro- structure as compared to previous investigations. In addition, a wider frequency tuning range has been achieved through a proper DC bias voltage arrangement.