Low-profile rotational electret generator using print circuit board for energy harvesting from arm swing

Rotational electret energy harvester (EH) is prototyped for powering low-power electronics from human motion. Stator with electrodes and rotor with electret are fabricated using flexible print circuit board (PCB) technology, which makes it easier to combine with metal ball bearing for rotational support. The maximum thickness for the rotational part including the eccentric mass is as thin as 3.3 mm. Output power up to 80 μW has been obtained from arm swing during walking at 1.45 m/s in our initial test.