Ultra‐Sensitive, Ultra‐Linear, Temperature‐Robust Yarn Sensor for Intelligent Monitoring Under Harsh Thermal Condition

ABSTRACT Textile sensors are pivotal for next‐generation wearables, yet their advancement is hindered by challenges including nonlinear high‐sensitivity response and thermal drift. Here we propose a hierarchical assembly strategy to address these limitations and develop a temperature‐robust yarn sensor (TRYS). To fabricate high‐sensitivity piezoresistive fibers, we assemble modified S‐MXene nanosheets and silver nanowires (AgNWs) into the natural wool substrates, whose intrinsic hierarchical microstructure provides stable electrical contact and homogeneous stress distribution, thereby ensuring high sensitivity and linearity. These functionalized fibers are then twisted into sensing yarns and encapsulated using infrared‐reflective antimony‐doped tin oxide (ATO)‐filled polydimethylsiloxane (PDMS). Our TRYS exhibits great performance, featuring an ultra‐high gauge factor of 1468.43 with a linearity of 99.9%, a remarkable linear gauge factor (LGF) of 367, rapid response/recovery times (40/98 ms) and a subtle strain detection limit of 0.05%. With the protection of the ATO/PDMS layer, the TRYS exhibits excellent thermal robustness, achieving a temperature reduction of 42.8 compared with pure wool fibers at 200. Furthermore, integrated with machine learning, our TRYS enables reliable real‐time physiological monitoring and gesture recognition even under extreme thermal variations, demonstrating its potential for early risk warning in firefighting applications.