Non-resonant electrostatic energy harvester for wideband applications
Presented is a novel non-resonant electrostatic energy harvester targeted at the wideband frequency response for micro-system powering. To boost non-resonance power output under low frequency, the vertical gap changing method is adopted to induce variable charges, which generates approximately 17 times of charge change compared with the conventional method of laterally changing overlap area (at 1 mm gap). Further, to boost the low frequency and non-resonant power generating capability, the differential structure is adopted to achieve doubled output voltages. Testing results reveal that optimal output power occurs when the inner plate is of large effective movement range and large relative displacement with surrounding electrets. Maximally, 3.9–7.0 V voltage and 0.2–0.7 μW power are achieved over the 5–120 Hz frequency range.