Thermal energy harvester using ambient temperature fluctuations for self-powered wireless IoT sensing systems: A review

This paper comprehensively explores a cutting-edge approach that harnesses daily ambient temperature fluc-tuations to generate usable energy for self-sustaining wireless Internet of Things (IoT) sensing systems. With conventional power sources like batteries present limitations in energy capacity, maintenance, and environ-mental impact, and one of the alternatives is harvesting energy from the device's surroundings. The study es-tablishes a foundation by presenting the principles of thermoelectric generators (TEGs) and highlights recent breakthroughs in TEG fabrication technologies. Additionally, the paper extensively investigates the use of phase change materials (PCMs) as crucial heat storage materials, laying the groundwork for further research. At its core, the paper reports the concept of heat storage TEGs, bridging the gap between ambient temperature fluc-tuations and electricity generation. These groundbreaking TEGs leverage the dynamic shifts in ambient tem-perature, providing a sustainable and efficient solution for powering IoT sensors. A practical demonstration showcases a self-powered wireless sensing system utilizing daily ambient temperature variations. The system efficiently employs PCMs to maintain temperature differentials that drive TEGs, resulting in electricity genera-tion. This research underscores the feasibility and potential of such systems, emphasizing their capacity to function autonomously in real-world conditions, even without dedicated heat sources. Future research in this field is poised to concentrate on improving the performance of TEGs though the investigation on high-performance thermoelectric materials, advancements in fabrication technology, and ensuring long-term reli-ability. Furthermore, optimizing the performance of the PCMs, encompassing considerations such as sufficient latent heat, an appropriate melting point, and a sufficient volume, is crucial. Beyond these considerations, the integration with other components, such as gas sensors and actuators, is essential for the widespread adoption of self-powered wireless IoT sensing systems in practical applications. The exploration of scalability for large networks and the conduct of comprehensive environmental impact assessments are pivotal areas of inquiry, ensuring that these advancements align with sustainability goals and real-world deployment requirements.