A wide-bandwidth MEMS energy harvester based on a novel voltage-sliding stiffness tunability

Abstract

Due to the significance of power harvesting technologies in making use of the energy sources available in the surroundings, in this research, an innovative piezoelectric energy harvesting mechanism with adjustable stiffness is presented. The presented design performs based on the transverse motion of the two microbeams supported at one end. The beams are sandwiched between two piezoelectric layers and are in exposure to an external acceleration field. At the free end of the microbeams, a rectangular microplate is embedded as a slip-over electrode without an electric charge. A thin dielectric layer separates the microplate and two other stationary electrodes. Once a constant adjusting voltage is applied through the stationary electrodes, the free electrons’ displacement in the microplate causes the plate to encounter a nonlinear deflection-dependent electrostatic force. The produced electrostatic will perform as an electric spring so that its stiffness can be altered by the applied adjusting DC voltage. As the rigidity coefficient of the electric spring can be controlled easily, it makes the structure a wide-frequency bandwidth energy harvester. Mathematical modeling of the design has been analyzed to demonstrate the structure's nonlinear vibration behavior coupled with the harvesting section of the system. The derived equations are solved altogether after being discretized by the use of the Galerkin method. The energy harvester's steady-state response in various harmonies is found by applying a learning-based method. Also, the appearance of the main resonance as well as secondary resonances in the energy harvester's response in the frequency domain in different harmonies can be analyzed. The design's geometric effect on the power harvester's effective performance is examined in detail. The power harvester's output power versus the impedance and also the structure's output power density undergoing the external acceleration are investigated.