Resonant inductive coupling for wirelessly powering active implants: Current issues, proposed solutions and future technological attempts

Since the 20th century, portable electronic devices such as laptops, cell phones, tablets, and medical implants have emerged in our daily life. All these devices are mainly power supplied by batteries. However, their lifespan is a major disadvantage. This challenge becomes more critical when it comes to Implantable Medical Devices (IMDs). Therefore, Wireless Power Transfer (WPT) is considered as a promising alternative to overcome this challenge. The near-field magnetic WPT approach is a common-used way to power-up active implants wirelessly. Although many improvements have made on the implant’s design and their remote powering approaches, stringent requirements and several parameters should be considered during the design of the WPT system, such as the power transfer efficiency, the transfer distance, the implant size, and its biocompatibility. In this paper, a comprehensive study of the commonly proposed approaches to power-up IMDs have been reviewed. In particular, various advanced mechanisms and technical solutions related to the Near-field magnetic WPT approach have been discussed. These solutions are carried out to optimize transcutaneous WPT transfer efficiency, maintaining robustness and safety against many factors such as coil misalignments and load variations. Human safety concerns and exposure limits to the electromagnetic field by respecting international guidelines are also explored in this review. Finally, a summary of relevant information and directions for future research investigations are provided.