eMeD: An Experimental Study of an Autonomous Wearable System with Hybrid Energy Harvester for Internet of Medical Things

Abstract

We propose and experimentally validate a hybrid energy harvester embedded in a wearable system used to measure real-time information, such as body temperature, heartbeat, blood oxygen saturation (SpO2), and movement (or acceleration) of human body in real time. This hybrid energy harvester, or in short eMeD, has a unique design that can improve the energy efficiency of the overall wearable system and extract more energy from ambient sources. Specifically, the wearable system is integrated with a hybrid photovoltaic-radio frequency (RF) energy harvester as the power source to prolong its lifetime and reduce the dependence on battery energy. Experimentally, the current consumption of the wearable system with load switching and event management algorithm improved from 31 mA to 18.6 mA. In addition, the maximum conversion efficiency is 14.35%. The experimental results illustrate a sustainable and long-term monitoring operation for Internet of Medical Things systems.