Development of a low frequency electrostatic comb-drive energy harvester compatible to SoC design by CMOS process

A 3000 μm × 3000 μm × 500 μm in-plane, gap overlap, electrostatic comb-drive operating in charge-constrained cycle is developed to harvest ambient vibration. This is the smallest vibration harvester resonating at 105 Hz, implementable by standard CMOS process and compatible to System-on-Chip (SoC) design. The 2000 μm × 2200 μm × 450 μm (4.9 mg) vibrating mass is made of the CMOS handle layer so as to achieve low frequency operation. Design verifications show that, with the excitation input of 10 μm amplitude at 105 Hz, the harvester can generate an average output power of 0.0924 μW, or equivalent output density 0.021 μW/mm³. The design is the most area-efficient CMOS vibration energy harvester reported to date.