Electret Energy Harvester Vibrated at Collision Induced Natural Frequency

摘要

This study demonstrates the electret type inertial energy harvester for low-frequency vibrations such as human movements. Because a moving mass of the harvester is supported by the very soft spring, the mass collides easily with the frame structure. This collision induces the higher natural frequency vibration to the mass even at the applied vibration frequencies below the natural resonant frequency, which improves the efficiency of the power generation. The fabricated device generated the power of 1.8 nW_(rms) for applied vibration of 20 Hz and 200 μm_(p-p) with the optimal load resistance of 32 MSI. The packaged device size is 0.23 cm3 and the weight of the moving mass is 122 mg.