Novel vibration-driven micro-electrostatic induction energy harvester with asymmetric multi-resonant spring

We developed an asymmetric gammadion spring electrode for wide band vibration as a counter electrode for the electret electrode film of a micro electrostatic energy harvester. A vibration-driven micro power generator with a high-Q mechanical resonator works efficiently under single-frequency vibration, but, the associated narrow operation frequency bandwidth tightly limits the power output under normal wideband vibrations. To solve this problem, we therefore present concept, design, simulation, fabrication, and evaluation of our novel micro generator based on electrostatic induction using electret. The asymmetric gammadion spring is made of stacked SU-8 and has three vibration modes. For mode 1 vibration the maximum power output our generator was 7.48 nW at 110 Hz, for mode 2 vibration it was 2.19 nW at 165 Hz, and for mode 3 it was 1.72 nW at 243 Hz.