Recent years have witnessed explosive increase in the number of wearable devices in the market and industry. However, hardly have these devices gained the ability to capture energy from hosts and then get self-charged. In this paper, we design and build a novel disk-shape and watch-size wearable electromagnetic energy harvester to scavenge the swinging energy of human arms during walking and running. The design is composed of mainly three parts: a magnet array, a coil array, and a mechanically excited mechanism. The harvester adopts an eccentric swing mechanism, which converts low frequency (≤5Hz) human motion energy into mechanical kinetic energy. Meanwhile, we employed an array of alternating south- and north-pole magnets. This arrangement allows the array exhibits a unique phenomenon, i.e. abrupt magnetic flux density changes within the array. Because of this phenomenon, the harvester displays excellent performance such as relatively high voltage and high power output. We then conducted FEM analysis to validate the hypothetical abrupt flux density changes. A prototype was fabricated for experimental studies. We investigated open-circuit voltage outputs, output current, and power as well as charging performance into energy storage components. The energy harvester, as a renewable portable power source, can be of great significance for powering smart wearable electronic devices and health care monitoring sensors.


Harnessing Kinetic Energy From Human Motions With a High-Efficiency Wearable Electromagnetic Energy Harvester

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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