Enhanced Room-Temperature NO₂Sensing via a Reduced Graphene Oxide/CuO Composite on Flexible Nylon Fibers

To address the need for compact, flexible nitrogen dioxide (NO₂) gas sensors capable of operating under complex wearable conditions, this study presents a composite gas-sensitive structure comprising reduced graphene oxide/copper oxide (RGO/CuO) integrated with a flexible nylon fiber. The proposed sensor demonstrates reliable detection of low-concentration NO₂gas at room temperature, offering benefits such as compact size, lightweight design, excellent flexibility, and superior gas-sensitive response. RGO was incorporated onto the nylon fiber surface through a straightforward infiltration technique, followed by the growth of a zinc oxide nanowire array on the RGO nylon fiber via a water bath method. This process enhances the specific surface area of the gas-sensitive film. The RGO material was doped and modified with CuO nanoparticles, with additional regulation of the oxygen vacancy concentration. Testing revealed a detection limit of 0.5 ppm. Within a NO₂gas concentration range of 2–10 ppm, the sensor exhibited a linear increase in responsiveness, demonstrating excellent room-temperature response. The gas-sensing enhancement mechanism was investigated, identifying the synergistic effects of the heterogeneous structure, the high specific surface area of the film, and the high carrier mobility as key contributors to its performance. Additionally, a low-power monitoring and early warning node powered by a lithium battery was developed, and the reliability of the wearable sensor system was verified. These results underscore its substantial application potential in wearable electronics.