A 403 MHz Wireless Power Transfer System With Tuned Split-Ring Loops for Implantable Medical Devices

A near-field wireless power transfer (WPT) system for implantable medical devices, such as pacemakers, is proposed. Operating at 403 MHz within the medical implants communication service (MICS) band, the WPT link constitutes a primary loop to be based outside the body as a transmitter and an implantable loop with a single-turn as a receiver. Simulation and experimental results show that the proposed link offers good power transfer efficiency (PTE) performance. The maximum measured PTE of the proposed link is 57.9% at a transfer distance of 6 mm through 1 mm of air and 5 mm of body tissue. The maximum input power that can be supplied to stay within specific absorption rate safety guidelines is 159 mW. A rectifying circuit is designed to convert 403 MHz RF signals to dc for a 1.5 $\text{k}\Omega $ load with a measured conversion efficiency of 73.2%. The measured end-to-end PTE of the proposed WPT system is 42.4%.