Abstract
The increasing popularity of wearable devices, particularly smartwatches, has highlighted the limitations of conventional battery-powered systems, with most smartwatches requiring frequent charging due to short battery life. This issue disrupts user convenience and limits the functionality that can be incorporated into such devices. To address this limitation, this paper presents a novel approach by harnessing human body heat as a renewable energy source to power smartwatch batteries using thermoelectric generators (TEGs). The proposed energy harvesting system leverages the temperature difference between the human body and the surrounding environment to generate usable electricity. By incorporating flexible TEGs and an optimized heat sink design, the system effectively captures thermal energy and converts it into electrical power, producing up to 3.55 V and 1 A under a temperature differential of 8.5°C. Experimental testing demonstrates that this approach significantly extends the operational lifespan of smartwatches by reducing the frequency of charging, making it an attractive alternative for enhancing user convenience and improving device sustainability. The incorporation of this energy harvester allows smartwatch manufacturers to overcome the trade-offs between battery life and functionality, thus offering users an uninterrupted experience without sacrificing performance. This paper also explores the impact of various environmental factors, such as ambient temperature and skin contact, on the performance of TEGs. Additionally, the potential for scaling up this technology and commercializing it for widespread use in future smartwatch designs is discussed, with an emphasis on optimizing efficiency and adapting the technology for diverse wearable applications.