Beyond Heat Harvesting: Thermoelectric Materials and Hybrid Devices for Smart Sensing and Sustainable Technologies

Abstract Heat is a plentiful energy source available within us and in our surroundings, yet it is still underutilized and wasted. Capturing even a small fraction of this energy provides an opportunity to contribute to an eco‐friendly and sustainable society. Although traditional solid‐state inorganic semiconductor materials have led the research stage of thermoelectric (TE) energy conversion, carbon‐based hybrid materials and hydrogels provide an emerging TE platform for wearable, flexible, and low‐temperature energy harvesting devices for powering sensors. These materials have expanded the application of these thermoelectric materials beyond heat‐to‐electrical energy conversion to power various smart devices for use in healthcare monitoring and environmental remediation. This review is divided into three main categories. First, this work focuses on the fundamentals of TE generators and their classifications. In the second section, a thorough discussion of integrated sensor fabrication, including single and hybrid systems and their performance matrices, is given. Special attention is given to self‐healing materials that improve device longevity and achieve environmental sustainability. Section three discusses the incorporation of machine learning (ML) techniques into TE‐powered sensors. By emphasizing the latest discoveries to tabulate the entire range of thermoelectric‐powered sensors, this review bridges materials science, wearable technologies, and advanced engineering.