Wireless power transfer has drawn great interest from many researchers. Electronic biomedical devices can be powered up either by an external power cord or by batteries. However, an external power cord may limit the mobility of a person and batteries tend to have a very limited power capacity. When the battery of implantable medical device has run out, surgery for replacement battery is needed in order to sustain their life. Hence, a wireless power transfer system is proposed to solve the problems by charging the medical implant wirelessly. This wireless power transmission system conveys the power by magnetic resonant coupling technique. In order to improve the efficiency of system, a novel lumped element impedance matching approach was introduced by a specified ratio of LC formula. The prototype transfer power with 60% efficiency and to a distance of 1 time the transmitter coil diameter. Other electronic devices that can be implemented with this WPT system are cell phone and laptop.
While designing the system, few issues need to be considered. First foremost, the operating frequency and the PTE of the system to ensure sufficient amount of power is transmitted to charge or operate the receiver devices. To achieve that objective, the design of circuit and coil must be optimized. Besides, the WPT system may be able to charge the device through the air efficiently, however, when it comes to human tissue as the transfer medium, the energy transfer performance will be degraded since human tissue is a lossy dielectric as observed in few recent studies. Hence, analysis need to be carried out to make sure the system is still able to perform in human tissue environment. Next, the safety of the system must be guaranteed that it does not cause harmful biological effect on human. Currently, there are two safety guidelines which are ICNIRP Guidelines and IEEE. Both the safety guideline has provided the recommended Specific Absorption Rate and induced electric field levels.
transfer power to a place which is difficult to assess, such as biomedical implant inside human body
provide charging port/area to users without the need of cable, such as table which can charge phones and laptop on it