A Wearable Patch Based on Flexible Porous Reduced Graphene Oxide Paper Sensor for Real‐Time and Continuous Ultraviolet Radiation Monitoring

Abstract Real‐time and continuous monitoring of ultraviolet (UV) radiation in daily activity is critical in diverse fields ranging from personal fitness, cosmetics, to medical aspects. Here, a wearable UV monitoring patch that can be easily fixed/removed at desired locations and provide real‐time and continuous UVA levels in daily life is developed. The wearable patch consists of a highly sensitive, flexible graphene sensor for UVA measurement and a multifunctional fabric patch integrated with commercial electronic components for signal processing, wireless transmission. To achieve a high sensitive UVA sensor with high flexibility and long‐term stability, porous reduced graphene oxide (pRGO) papers are fabricated by simple solvent evaporation followed by thermochemical reduction. The flexible UVA sensors based on pRGO papers feature a high UVA photoresponsivity of 125 mA W −1 , which is comparable to that of a commercial silicon‐based UV sensor. Furthermore, the polydimethylsiloxane‐encapsulated pRGO (PDMS‐pRGO) sensors exhibit stable UVA photoresponse characteristics that is maintained under severe conditions, such as a large number of bending cycles, thermal heating, and high humidity. The use of wearable patches that enable real‐time, wireless monitoring of personal UVA levels in various practical applications are demonstrated.