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

Abstract

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.