Wireless Power and Antennas for Bio-Implants

The evolution of wireless power and data telemetry technologies fueled by continued advances in electronic systems and miniaturization of antennas and components played an important role in design and development of wireless medical devices in personal healthcare. This has led to numerous applications in medical diagnostics and therapeutics ranging from in vivo cardiac pacemakers and defibrillators to emerging devices in visual prosthesis, brain computer interfaces, and body area networks for sensing oxygen, glucose, pH level, pressure, temperature, and other medically useful quantities. Neural implants have become ubiquitous with some of them receiving FDA approvals for commercial use recently. Implants powered using batteries have limited life time and a surgical intervention is required to replace them. As batteries have finite recharge cycles, wirelessly charging the batteries only provides an incremental lifetime. Battery-free operation using sustainable wireless powering can extend the lifetime of implants as long as needed. An antenna is one of the most important components to ensure robust link performance. It is a great challenge to design an antenna inside a human body as critical constraints such as biocompatibility issues, antenna size and safety concern should be considered. Besides, due to the complexity and variation of human tissues, wide bandwidth is required in case of frequency shift. In this presentation, different approaches for wireless power and miniaturized antenna used in neural implants will be introduced and their performances are compared against the implant requirements. Then we discuss in detail our wireless platform for peripheral nerve implants with neural recording and muscle stimulation functions starting from the design considerations, power and data link design and safety. The designed wireless platform is tested acutely in rats and the performance of the link is reported.