Implantable Magnetic Resonance Wireless Power Transfer System Based on 3D Flexible Coils

A magnetic resonance wireless power transfer system based on flexible 3D dual-coil is proposed and implemented in this paper. Firstly, a magnetic coupling resonant circuit model based on dual-coil is established, and the analysis indicates that enlarging the coil inductance and quality factor can effectively improve the transfer efficiency and performance. The coil parametric model is created by HFSS (High Frequency Structure Simulator), the effects of structural parameters on the coil inductance and quality factor are analyzed, and the optimized coil structure parameters are determined. To achieve maximum power transfer, the coupled resonant model after impedance matching is established and simulated in HFSS, and S11 reaches 30 dB at 13.56 MHz. Considering the radiation on human tissues, the SAR (Special Absorption Rate) value is evaluated simultaneously. To confirm the validity of the proposed prototype, the efficient wireless power transfer system composed of two flexible and biocompatible coils with 10 mm radius has been verified by the experimental measurements, and measure results show that the output power is 70 mW, when the transfer distance is 6 mm, the input power is 200 mW, and the maximum transfer efficiency is 35%.