Recent advances in wireless energy transfer technologies for body-interfaced electronics

Abstract

Wireless energy transfer (WET) technology has been extensively explored over the past decades as an ideal solution for supplying energy to body-interfaced electronics. The utilization of wireless, battery-free devices powered by WET offers high potential for conformal applications in body interfaces, particularly by accommodating repetitive body movements and ensuring a robust power supply. Owing to these attractive features, WET can serve as an alternative to conventional batteries for body-interfaced electronics, addressing challenges including the periodic replacement of batteries, size constraints in a limited target area, and intrinsic rigidity. Furthermore, the untethered system of WET can eliminate the obstruction of user movement, leading to improved applicability of body-interfaced electronics in daily life. In this review, we categorize WET technologies based on their energy sources, distinguishing between external energy obtained from outside the body and internal energy obtained from the body itself. We conducted a comprehensive review of strategies for applying WET technology in body-interfaced electronics, along with recent advances that have adopted unconventional approaches. Furthermore, this review provides additional perspectives on future directions for more practical applications of WET-based body-interfaced devices.