A Wireless Power Transfer System with Planar Split-Ring Loops Resonators for Implantable Medical Devices Applications

This study proposes a wireless power transfer (WPT) system based on inductive coupling for powering implantable medical devices (IMDs). The system operates at 403MHz, within the Medical Implant Communication Service (MICS) band. It consists of two resonators utilizing split-ring loops geometry. A power transfer efficiency (PTE) of 16.58% is achieved at a transfer distance of 12mm through living tissue. The transmitter and receiver feature compact dimensions of 25mm × 25mm × 1.52mm and 14mm × 14mm × 1.27mm, respectively. These are among the smallest dimensions reported for resonators based on planar split-ring loop geometry. Electromagnetic (EM) simulations were performed to optimize the geometry for maximum efficiency while maintaining reduced dimensions at a 12mm transfer distance. According to simulation results, the maximum received power, limited by specific absorption rate (SAR) regulations, reaches 105.5mW at 8mm and 29.44mW at 12mm. The resulting compact size and level of maximum received power are sufficient to enable integration within implantable medical devices such as cardiac pacemakers, cochlear implants, and certain neurostimulators.