Implantable Radio Frequency Wireless Power Transfer System for In-Body Heat Induction

Abstract

The application of electromagnetic radio frequency waves extends beyond the purpose of communication, to reach out to medical implementations in different forms. Such implementations vary from sensing to treatment. For example, electromagnetic waves can be used in on-body adapted electronics for sensing and monitoring or for electrical nerve and muscle stimulation, diathermy treatment, and many others.

Inspired by the far-reaching aims of this technology, this research was dedicated to studying, designing, implementing, and testing a fully implantable Radio Frequency system based on wireless power transfer technology. The system consists of a miniaturized meandered antenna connected to an inductive heating circuitry through a differential matching network. The miniaturization of the system was successfully achieved by leveraging a plethora of techniques. The system is designed with a cascade of components that direct the received RF signal into a customized meandered coil design integrated with an interdigitated capacitor. In this work, we prove the validity of this system and approach and its superiority in comparison to existing traditional bulky inductive heating components.

For this work, the adopted propagation channel is the human body. Various body layers are included, with their dielectric characteristics according to the targeted frequency of operation within the microwave range of the spectrum. The simulation results are validated according to the constraints of the input signal power, the antenna realized gain, and the specific absorption rate (SAR). As for the experimental testing, the measurements were collected using artificially fabricated phantoms and ex-vivo animal testing. Measurement of wireless power transfer through biological tissues to the implanted proposed system exhibited results that correlate highly with simulated and predicted data. Such results were verified with an incremental rise in temperature proving the applicability of this system in real-life scenarios. This work paves the way for new possible medical treatments based on non-invasive wireless heating of in-body components.