Wireless liquid-alloy-based induction heating for soft devices by alternating magnetic field: From characterization to application

Soft heating has attracted remarkable attention due to its extraordinary potential in the emerging multifunctional thermal applications, e.g. heating clothing, thermal therapy and therapy support products. However, current soft heating devices are mostly realized by wired configurations, which will constrain the overall flexibility and increase wiring complexity, especially for discrete multipoint circuits. Here, we propose a wireless liquid alloy induction heating method through a high-frequency alternating magnetic field (AMF), and can achieve rapid wireless heating for fully intrinsically soft devices. Then, we characterized the heating performance under different sizes and their quantitative relations. Further, we found a new phenomenon that liquid alloy continuously shrinks into a ball shape in AMF by mutual repulsion force based on the skin effect. Finally, we demonstrated a wireless trigger detection circuit for AMF and a fully soft wireless electric hot water bag with comparable performance to commercials. This work provides a convenient and rapid wireless heating technology option for fully soft devices and is potential for wireless functional devices and thermal therapy.