Harnessing human motion energy by a rolling-swing electromagnetic energy harvester with counter-rotations

Nowadays, the demand for portable devices has been rapidly increasing with the development of the Internet-of-Things technology. However, traditional batteries face challenges to meet the design requirements of portable devices for lightweight and long-term operation. This work proposes a rolling-swing electromagnetic energy harvester (RS-EMEH) which harvest energy from human motion to serve as an alternative energy source for such devices. RS-EMEH creates the counter-rotations between magnets and coils, thereby amplifying the magnetic field variation within a single cycle of ultralow- frequency excitation of the human motion. The prototype of the proposed RS-EMEH is then built and its performance is experimentally characterized. The outcomes from experiment displays that the RS-EMEH can provide milliwatt-level output at the walking speed ≤ 3.5 km/h, sufficient to power portable wireless low-power electronic devices.