Design and Analysis of Double-Layer Electromagnetic Field Limiter for Wireless Rechargeable Medical Implants

Human exposure to the electromagnetic field (EMF) has been raising concerns with the fast development of the wireless power transfer (WPT) technology. This article proposes a double-layer coil structure for wireless rechargeable implanted medical equipment, which can effectively strain the power beam into a single direction and limit the EMF emission to other parts of the human body. The system is designed and analyzed based on both the finite-element method (FEM) simulation and practical tests. A prototype of the proposed double-layer receiver with 56 mm diameters has successfully captured 6.84 W power and the EMF emission strength has been effectively reduced by over 20% at the concerning parts of the human body during WPT. The design scheme has been analyzed based on practical considerations and can be embedded into other similar medical implant applications.