A Versatile MEMS Electrostatic Transducer Structure To Achieve Near-Zero Stiffness For Low-Frequency Energy Harvesting

This paper presents an inertial structure with electrically controllable stiffness, enabling adaptive low-frequency operation in vibration-based MEMS energy harvesters. The structure design combines bistable and linear springs with different electrostatic transducers to maintain overall stiffness to close or equal to zero over the operational range of proof mass displacement. In the zero-stiffness mode, the simulation results show that a maximum displacement amplitude can be achieved within a low-frequency range of $f \leq 14 \mathrm{~Hz}$, even when excited by an extremely small acceleration of $A=5 \times 10^{-3} \mathrm{~g}$. As an added feature, the harvester can be adjusted to operate in either linear or bistable mode by tuning the linear electromechanical forces of the integrated transducers. Multimode operation of the proposed structure can offer a versatile solution that effectively adapts to the diverse frequency characteristics of real-world ambient vibrations.