Dip-coated stretchable fabric strain sensor using a SEBS/TPU/CNC@carbon black composite

• A strain sensor based on commercial fabric was fabricated with flexible structure, rapid response, and good sensitivity. • Inclusion of CNC significantly enhanced CB dispersion and reinforced the polymer matrix stability. • Uniform Joule heating and reliable strain sensing confirmed applicability for dynamic wearable use. Flexible fabrics are widely used in clothing and sportswear, yet their potential for sensing applications remains underutilized. Although there are already many commercialized stretchable fabrics with flexibility, their sensing functionalities have not been fully explored. The development of flexible, commercialized strain sensors is hindered by several critical challenges. Key limitations include the lack of electrical conductivity in market-available flexible fabrics and limited fabrication methods that offer stable electromechanical performance under repeated deformation. In this study, a scalable solution-blending and dip-coating strategy to dip-coat the commercialized fabric is employed with a nanocomposite solution based on thermoplastic polyurethane, styrene-ethylene-butylene-styrene, cellulose nanocrystals, and carbon black to shape the sensor. The resulting sensors integrate a percolating nanoscale conductive network with a macroscale fabric scaffold, achieving gauge factors up to 3.77, rapid response and recovery (<0.75 s), and excellent durability over 1000 loading cycles at 50% strain. Furthermore, the sensor exhibits uniform Joule heating with a fast thermal response, confirming the stability of its conductive network under electrical load. Real-time monitoring of human joint motions (finger, wrist, and knee bending) demonstrates conformability, signal stability, and long-term wearability. This work presents a scalable approach that enables existing elastic textiles to function as advanced strain sensors and wearable electronics.