Electromagnetic Energy Harvester Targeting Wearable and Biomedical Applications

This work presents a miniaturized electromagnetic energy harvester (EMEH) based on two coils moving in a head-to-head permanent magnet tower. The two coils are separated by a set distance so that the applied force moves the EMEH from one equilibrium position to another. In this configuration, the harvester produces energy in two different working modes: when a force is applied to the moving part or when an external random acceleration is applied to the whole system. A custom test bench has been designed to characterize the behavior of this energy harvester under a variety of conditions encountered in wearable applications. Notably, at 10 Hz and 1.32 g RMS acceleration, our inertial EMEH demonstrates its capability to sustain a consistent output power of 1696 mu W within a total volume of 22.39 cm3, showcasing its efficiency in environments with erratic stimuli typical of wearable and biomedical applications. The presented EMEH is compared with reported inertial EMEH structures to extract its design limitations as well as future improvements, situating the present work in a comprehensive state-of-the-art and defining a generic performance target for biomedical and wearable applications.