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

With the rapid development of biomedical and microelectronics,implantable medicine has gradually become an important approach of adjuvant therapy and health monitoring.The implantable medical device can effectively acquire various physiological signals and perform implantable fixed-point treatment,thereby contributing to a more reasonable and efficient treatment program.Unfortunately,the power supply of these implantable medical devices has always been a limiting factor suppressing the rapid development.Traditional battery power has many drawbacks such as bulky,requiring regular replacement,poor biocompatibility and safety.Wireless power transfer can effectively solve these above problems.Compared with the inductive coupling,the wireless power transfer system based on magnetic resonance has higher transfer efficiency and anti-interference ability.In order to realize wireless power supply for implantable medical devices,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 the performance.The coil parametric model is created by HFSS(High Frequency Structure Simulator),which respectively performs the coil turns,radius,wire pitch and wire width,the effects of these structural parameters on the coil inductance and quality factor are analyzed and the optimized coil structure parameters are determined.To ensure the input signal is transmitted at maximum power,the impedance matching of the pre-coupled resonant model is designed,the resonant circuit and the coupled resonant model after impedance matching are established and simulated in HFSS,S11 reaches-30dB at the resonant frequency 13.56MHz.The signal processing modules at receiver are designed separately,and the rectifier,low-pass filter and voltage regulator modules are simulated in Multisim.Based on the simulation,the actual circuit of the above modules is built and verified.At last,the efficient wireless power transfer system composed of two flexible 3D coils with 10mm radius has been verified by the experimental measurements.The full-wave rectifier and low-pass filter modules at receiver provide regulated voltage,and measure result shows that the output load voltage is 8.35V and the output power is 70mW,when the transfer distance is 2mm,the load is 1k?,and the input power is 200mW,the maximum transfer efficiency is 35%.