Self-powered wearable ultraviolet index detector using a flexible thermoelectric generator

Self-powered wearable electronics have attracted extensive attention due to the limited power supply of traditional batteries. Small sized and flexible thermoelectric generators (TEGs) can harvest body heat and convert it into electricity, which is a promising approach to obtain a sustainable power source for wearable electronics. This paper develops a self-powered wearable ultraviolet index (UVI) detector, which is enabled by using a flexible TEG as the power supply. The design of the wearable UVI detector, including the driven circuit, voltage conversion and UVI detection modules arc presented. The step-up chip is utilized in the voltage conversion module to boost the relatively low voltage, which is generated by the TEG. The output power is stored by the capacitors, which can wake up the UVI sensor for detection periodically. Then, the prototype UVI detector is fabricated and its detection performances are characterized. Wrist wearing experiments showed that the wearable UVI detector can be successfully self-powered by harvesting human body heat. Also, the proposed wearable UVI detector can measure the environmental UVI under different weathers and protections, which can provide a reference for the daily dressing and healthcare applications.