Design optimization of a wide band MEMS resonator for efficient energy harvesting

Wide band MEMS resonators banking on the principle of amplitude dependent stiffness nonlinearity as reported in few recent publications can stretch the frequency response. A recent report by our group on four internal proof mass based membrane resonator has been observed to vibrate below 350 Hz with more than three closely placed peaks within 2kHz in the frequency response without introducing non-linearity. However, improvements in the design of such wide band MEMS resonators operating in the linear regime are required, so that the lower frequency range can be reduced further. In this paper we have optimized the lateral dimensions and displacements of the internal proof-masses by introducing a figure of merit to estimate the performance of these resonators. The figure of merit incorporates three parameters viz. power output per unit area, lower cut off frequency and no peaks in the operating frequency range within 2 KHz (most of the practical vibration sources lie within it). It has been observed that the resonator with four internal proof-masses each of dimensions 3×2mm2placed 0.5mm apart from each other shows highest figure of merit.