Galvanically Coupled Intrabody Communications for Medical Implants: A Unified Analytic Model

Health-care monitoring and diagnostics technology continues to be of great interest in research due to an increasing trend in the number of people with chronic diseases. To improve accuracy and timeliness of diagnosis, electronic devices could be implanted inside human body to provide various real-time diagnostic information. However, effective technique for communicating the implant with outside world is still an open problem. Early efforts based on radio wave propagation are standardized as the medical implant communication services (MICSs) for 402-405-MHz frequency range, which was later adopted as medical device radiocommunication services for 401-406-MHz frequency range. Intrabody communication (IBC) is a relatively new technique that uses the human body as a channel with communication frequencies not exceeding several megahertz. In this paper, we propose a new analytical electromagnetic model that uses galvanically coupled IBC as an alternative to radio wave-based implant communication. The model is unified in the sense that it is based on multilayered ellipsoidal geometry that can be applied to any part of the body (i.e., head, torso, limbs, and so on). Our model effectively describes the influences of tissue layer thicknesses and electromagnetic properties, implant size and depth, and geometry of the body part. The model proves the security and low power consumption of IBC. The path loss characterization of IBC implants shows lower values compared with their MICS counterparts.