Frequency conversion interposer with no-internal stress curved-beam for MEMS vibrational energy harvesters

The generating efficiency of an micro electro mechanical system vibrational energy harvester (MEMS VEH), which converts vibrational energy into electrical energy, is maximized at resonance. However, because the resonance frequency of an MEMS VEH is an order of magnitude higher than the vibrational frequency in the environment and not only has a high Q value, but the frequency of vibration in the environment changes randomly, it is difficult for MEMS VEHs to harvest vibrational energy efficiently. In this study, we propose a method to improve the generation efficiency of MEMS VEHs using a Frequency Conversion Interposer (FCI) that vibrates nonlinearly with its bistable no-internal stress curved-beam. As a simulation model combining FCI with the MEMS VEH, we fabricated a Two-Dimensional Monolithic Structure (TDMS) with a curved-beam and a straight beam that mimicked the FCI and oscillatory structure of the MEMS VEH, respectively. It was observed that the vibration of the straight beam induced snap-through (ST) of the curved-beam of the FCI, and the measured acceleration was more than 1.3 times the applied acceleration applied from the FCI to the MEMS VEH. As the power generation of the MEMS VEH is proportional to the square of the applied acceleration, the FCI is useful for improving the generating efficiency of the MEMS VEH.