Study And Optimizing Design Of Wireless Charging System For Implantable Medical Equipment

With the continuous development of contemporary information science and medical level,the implantable medical devices plays an important role in medical diagnosis,treatment and monitoring.Yet,the traditional implantable medical devices are always faced with some problems,for example,short battery life,frequent surgery replacement of the battery easily leads to wound infection,as well as charging the battery in the body makes the local tissue temperature high.The wireless energy transmission technology can effectively solve the above various problem.Therefore,it is widely used in the field of implantable medical electronic systems through the coupling of near-field magnetic field,and electrical energy is delivered to the implanted components through the coupling of near-field magnetic field,meanwhile,it realizes real-time data exchange.Currently,the wireless charging system of implantable medical devices has been faced with such problems as how to improve the energy transmission distance and the wireless charging efficiency,reduce the value of special absorption rate(SAR)of human tissues for protect human health from the electromagnetic radiation.Based on the coupled-mode theory,this paper analyzes the fundamental principle of the dual-coil wireless energy transmission system to calculate the mutual inductance of the double ring coil in different structure,increase the transmission efficiency of the wireless charging system and reduce the SAR value of the antenna near-field electric field radiation.Additionally,this paper designs a set of highly efficient and safe implanted double-ring wireless charging system.The system consists of an external transmitter circuit,a dual coil coupling structure,an internal receiver circuit and load component.For the above wireless charging system,the main research work is as follows:Firstly,the related research background of wireless charging system in implantable medical devices and the development history of wireless energy transmission technology both at home and abroad are introduced.And the basic working principle of wireless energy transmission system is analyzed.Secondly,based on the theory of mutual inductance calculation of double loop coils,the main factors affecting the transmission efficiency of the system are analyzed and discussed.Newman integral formula method and Grover method are used to calculate the coil mutual inductance including the parallel coil,the axial offset,the radial rotation and the double parallel coil respectively with a certain width and thickness,as well as analyze the influence of spatial position parameters on mutual inductance.Finally,based on the theory of magnetic coupling and split method,a double-ring transmission and receiving antenna with embedded core structure and a split double-sided ring transmission antenna with high quality factor(Q)are proposed.Then,two antenna models with different structures are machined and tested.The results show that compared with the traditional single-coil coupling structure,the transmission efficiency of the split double ring structure is increased by about 27.8%and the SAR value is reduced by about 9.8%.Compared with the latter,the transmission efficiency of high-Q split double-sided ring structure has nearly doubled while the SAR value is decreased by about 23.61%.