Destructive Interference-Enabled Metasurface for Efficient Wireless Power Transfer in Implantable Medical Devices

Wireless power transfer (WPT) holds significant promise for enabling continuous operation of implantable medical devices (IMDs), overcoming the limitations of conventional power sources such as batteries and wired interconnects. However, energy transfer efficiency in radiative WPT systems is often hindered by pronounced reflection losses at the tissue–air interface. Herein, we report the design and fabrication of an ultrathin (~λ/26), flexible anti-reflection metasurface based on destructive interference principles to minimize reflection within the ISM band (5.725–5.875 GHz). Engineered using biocompatible polydimethylsiloxane (PDMS), the metasurface exhibits excellent mechanical conformability to skin, forming an integrated interface with the body. When coupled with a miniaturized implantable antenna and a directional external patch antenna, the metasurface significantly improves power transmission efficiency, yielding a 6.1 dB increase in the transmission coefficient without requiring bulky or multilayer impedance matching structures. Moreover, the system demonstrates stable performance under angular misalignment (up to 45°), lateral displacement, structural deformation, and variations in tissue dielectric properties. This study introduces a novel interface-engineering approach for enhancing transcutaneous energy transfer, paving the way for thinner, more efficient, and wearable bioelectronic systems.