Wireless charging for implants

Limb lengthening is a pivotal method in extending the length of deformed bones in disproportionately short limbs. In the limb lengthening treatment, the short bones will be cut and embedded with a metal rod which is powered by a motor. The metal rod will expand in the abnormal bones to enable it grow over several months [1]. However, one of the main obstacles is that the traditional battery cannot support the motor for a prolonged duration. So the aim of the project is to build a power supply system which can transfer energy by wireless charging. A wireless charging system, which can transfer electric energy, has been examined in the previous projects. Nonetheless, the transmission efficiency is not high enough. The transmitting antenna is too hot to use when the system is working. In addition, the receiving circuit is too large in size to insert. In this project, a lot of different types of transmitting antennas have been built, tested, and compared to obtain an excellent transmitting antenna which is efficient and produce less heat. Moreover, a new receiving circuit has been designed by using an industrial rectifier. Finally, the transmitting antenna made of multicore insulation wire solved the efficiency and heating problem. The received power in the same condition had increased from 0.031 W to 0.101W. Meanwhile the operating temperature of the transmitting antenna was significantly reduced such that it is not hot to the touch. With respect to the second research question, the size of the receiving circuit had been reduced by 75%. The most significant finding was that a theory based on skin effect was established to explain the reason why the transmitting antenna made of multicore insulation wire can achieve such good results. Thus, the existing wireless charging system has been greatly improved, and can be used in limb lengthening better.Bachelor of Engineerin