Programmable Polyaniline-Nanostructured Sensing Fibers via Microfluidic Spinning Chemistry and Their Wearable...

The development of flexible smart textiles urgently requires conductive fibers with high elasticity, wide strain response, and environmental stability. Conventional polyaniline (PANI)-based composite conductive fibers suffer from low production scalability, inconsistent nanostructure control, and compromised electromechanical properties, severely limiting their practical application in smart textiles. Herein, an innovative online in situ polymerization microfluidic spinning (OIPMS) strategy was proposed. This approach integrated solvent-exchange-induced phase separation for fiber solidification with in situ oxidative polymerization of aniline within a confined space. It enabled continuous growth of tunable PANI nanostructures on the surface of PANI/thermoplastic polyurethane (TPU) composite fibers in a single step, such as PANI nanoparticles, nanorods, nanowires, and nanosheets. Notably, PANI nanowires (PNWs) formed a densely entangled network on the fiber surface. The resulting PANI/TPU@PNW fibers exhibited optimized overall electrical, mechanical, and strain sensing properties: conductivity of 36.21 S/m, breaking elongation > 400%, breaking strength of 0.19 cN/dtex, coupled with a wide strain range (0-300%), high sensitivity (gauge factor = 24.2), excellent linearity (R² = 0.984), and rapid response times (200 and 300 ms). The PANI/TPU@PNW fibers also demonstrated multimodal sensing capabilities for detecting bending and pressure, while maintaining stability after 5000 stretching cycles and 30 machine washes. The excellent sensing performance mechanism stemmed from the multidimensional synergistic conductive network of matrix enhancement, surface cracking, and outer layer bridging. These fibers could also be sewn into smart textiles and were further integrated into smart dancewear, smart camouflage sleeve, and smart varicose vein stocking, demonstrating significant application potential in the fields of sports science, military communication, and medical monitoring.