An Ergonomic Wireless Charging System for Integration With Daily Life Activities

Abstract

In this article, we present a clothing-integrated wireless power transfer and harvesting system that uses a novel class of anchor-shaped antennas for wireless power transfer up to the 4-ft distance. Notably, the system allows wireless charging during daily life activities, such as sitting on a chair or while lying on a fabric surface. Owning to up to a 4-ft power transfer, a user may also walk around during the wireless charging. The proposed system features a novel anchor-shaped antenna, which is miniaturized than a loop antenna and extends the range of fringing fields. Furthermore, a textile-based rectifying circuit with RF-to-dc conversion efficiency of 77.23% at 22.5 dBm is proposed. The efficiency remains better than 60% for an input power from 2 dBm to 24 dBm. For garment integration, a system consisting of a rectifier and an antenna were prototyped by using embroidered conductive thread on denim fabric. To understand the effectiveness, wireless power transfer tests are conducted under mechanical deformations and misalignments. The resulting prototype was tested for power transfer of several mW power over an area of 4 ft × 4 ft and by using a 1-W transmitter. This textile power harvesting system can be used as an ergonomic charging platform to supply power to a wide range of wearable medical, Internet of Things, and portable devices.