Flexible Wearable Solar-powered Watch Straps for Energy Harvesting: Design and Performance Evaluation

With the diversification and smartification of wearable devices, the increasing energy demand has made device battery life a significant challenge. This study designs and implements watch straps based on flexible amorphous silicon photovoltaic cells, utilizing solar energy from the environment to provide auxiliary power support for wearable devices. The straps adopt a parallel connection method to effectively cope with the uneven solar irradiance distribution on the wrist. Through open-circuit voltage maximum power point tracking, the watch straps efficiently harvest energy during dynamic wrist movements. Under typical daily solar irradiance of 300W/m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, the output power can reach up to 5.52mW. In indoor low-light conditions, the output power drops to the μW level. Although the solar-powered watch straps are low-power energy harvesting devices, they can provide a stable 2.56V voltage supply for low-power devices when combined with efficient energy management and storage modules. The flexible wearable solar-powered watch straps provide a reliable solution to meet the growing energy demands of wearable devices.