Implanted sensors will enable the next generation of healthcare by in-situ testing of abnormal physiological conditions, personalized medicine and proactive drug delivery. These functions require energy efficient communication of data between implants through the body tissues, which is difficult to achieve via radio frequency (RF) waves owing to their high attenuation within the body. The project involves the design of a network protocol stack using weak electrical currents as the underlying communication mechanism, instead of conventional RF waves to connect the implants. This paradigm results in energy savings of two orders of magnitude compared to RF. This research will help in realizing diverse applications arising out from a network of connected implants that benefit athletes, military personnel, and other at-risk populations. The ability to proactively report physiological changes within the body will increase longevity of human life. The project incorporates outreach components targeting K-12 students, design of computer-simulation based projects, and demonstrations at public venues like science museums.
The research planned in the course of this project is the first effort to systematically devise networking protocols based on galvanic coupling of electric signals. It has the following goals: (i) explore the impact of the transmission frequency and power on signal reflection and refraction at the tissue boundaries for multicast communication, (ii) design of interference-free medium access schemes that take into account heat generated at the crossings of the signal paths for all simultaneously active transceiver pairs, for both CSMA and TDMA-based approaches, (iii) research new strategies and conduct performance analysis for optimal placement of on-skin relay nodes for retrieving the sensor data from locations in the body that minimize the data gathering latency while being constrained by feasible on-body locations, and (iv) the first simulator and testbed for galvanic coupled communication using ns-3, and will also propose ways to charge the implanted sensors through contact-less magnetically coupled coils.
