Design Guidelines for EM Wireless Powering of Miniature Battery-Free Implantable Devices

Wireless power transfer enables battery-free operation of implantable bioelectronic devices, ensuring long-term functionality without relying on bulky batteries. This paper provides design guidelines for efficient electromagnetic WPT to miniature deep-body implants. It compares near-field, mid-field, and far-field methods, focusing on mid-field WPT for improved efficiency for miniature devices at greater depths. Key factors such as frequency selection, transmitter and receiver design, and methods to reduce tissue losses are discussed. Strategies like wavefront shaping and metasurfaces are examined to enhance power delivery while meeting safety constraints.