EQS Res-HBC: A 65-nm Electro-Quasistatic Resonant 5–240 μW Human Whole-Body Powering and 2.19 μW Communication SoC With Automatic Maximum Resonant Power Tracking Nirmoy Modak , Student Member , IEEE

Abstract

Applications like connected healthcare through physiological signal monitoring and secure authentication using wearable keys can benefit greatly from the battery-less operation. Low-power communication along with energy harvesting is criti- cal to sustain such perpetual battery-less operation. Human body channel is known to be a promising alternative to wireless radio wave communication for low power operation through human body communication (HBC), as well as very recently demon- strated as a medium for power transfer through body-coupled power transfer. However, channel length (L) dependency of the received power makes it inefficient for L >40 cm. In this article, we utilize electro-quasistatic resonant HBC (EQS Res-HBC) with maximum resonant power tracking (MRPT) to enable channel length-independent whole-body communication and powering. We design the first system to transfer power and data from a HUB device to wearable energy-harvested NODE through the human body to enable battery-less perpetual operation. Measure- ment results show 240, 28, and 5 µW power transfer through the body in a machine–machine (large devices with strong ground connection), tabletop (small devices kept on a table), and wearable–wearable (small form factor battery-operated wearable devices) scenario, respectively, independent of body channel length, while enabling communication at 2.19 µW. This enables >25× more power transfer with >100× more efficiency compared to the state of the art for 100-cm body