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.