Effect of Body Materials on Transmission Efficiency and Resonant Frequency in Wirelessly Powered Personal Mobility Devices

Personal mobility devices (PMDs) are gaining ground as a modern form of transportation that can seamlessly connect the first and the last miles to public transportation. The batteries installed in these devices are currently charged via wires, which enforce unnecessary charging mainly done by humans and exposed electrodes that limit durability in outdoor use. To overcome these issues, we aim to introduce wireless power transfer (WPT) systems, in which PMDs get autonomously charged as they are placed at parking stations. Despite many research efforts on WPT for electric vehicles (EVs), however, adopting WPT systems for PMDs — which requires lighter weight than those for EVs — has not been well explored. Therefore in this paper, we (a) investigate how the body material of PMDs affects WPT performance and (b) explore potential designs of new PMDs that integrate WPT performance as a design requirement. Through evaluations on the shift in resonant frequency, Q factor, and power transfer efficiency, we present a PMD that can achieve efficient (> 90%) WPT without impairing basic functions as a mobility device.