Polyurethane Nonwovens Integrated with Nanocomposite as Twist-Assisted Healing Flexible Sensor for Ultrasensitive Room-Temperature NO2 Detection.

A twist-assisted healing flexible sensor for ultrasensitive and selective detection of nitrogen dioxide (NO2) at room temperature is developed by sequentially introducing the reduced graphene oxide (rGO) onto polyurethane (PU) nonwovens as the conducting medium, followed by decoration with the Au/Pd nanoparticles (NPs) and polythiophene (Au/Pd&PEDOT) composites as the pivotal sensing layer. The optimized Au/Pd&PEDOT@rGO@PU sensor exhibits outstanding performance across a wide NO2 concentration range (0.1-800 ppm), demonstrating improved sensitivity (≈27% to 1 ppm), rapid response /recovery characteristics (7 s/38 s), ultralow detection limit (2 ppb), and exceptional selectivity at 28 °C. Such superior NO2 sensing can be ascribed to the synergistic effect: the outer PEDOT coating exposes numerous sensing sites, the Au/Pd NPs exert excellent catalysis, and the rGO framework accelerates the charge transfer. More importantly, the sensor demonstrates remarkable mechanical properties, including good robustness, twist-assisted healing capability, and superior water resistance. Combining scalable fabrication, straightforward construction, and competitive detection metrics, this flexible sensor represents a promising platform for real NO2 monitoring applications.