Survey of energy scavenging for wearable and implantable devices

This paper reviews state-of-the-art methods of energy harvesting for implantable and wearable devices based on the available mechanical and heat energy sources in the human body. The development of a compatible and sustainable power supply for wearable and implantable devices is a demand to realize their continuous and high-performance operation, minimize the need for external energy sources, and increase the lifetime of the devices. Heat and mechanical movement are two available and reliable energy sources in the human body. Since mechanical and heat energy harvesting methods have been extensively studied over the past decades, researchers focus on developing techniques to integrate these energy harvesters with implantable and wearable electronics. Therefore, energy requirement for wearable and implantable devices, available energy level from the human body, and convenience and feasibility of the implementation are taken into account to provide full or partial power support. This survey aims to present recent findings and developments in the field of energy harvesting from continuous heat source and mechanical movements of the human body. In particular, working principles, technical details, and current status as well as issues and challenges of energy harvesting from human body including thermoelectric, photovoltaic, piezoelectric, electrostatic, electromagnetic, and triboelectric harvesters are discussed.