Highly Stretchable and Durable Electrospinning Polyurethane Nanofiber Composite Yarn for Electronic Devices

High-conductivity yarns with remarkable flexibility and sensitivity have great potential for application in manufacturing wearable electronics. However, the development of electronic textiles (E-textiles) is still limited by the insufficient extents of size manipulation and weight reduction. In this study, a novel nanofiber yarn with a high flexibility, durability, and sensitivity was prepared by a facile electrospinning technique. The composite yarn with silver nanowires used as a reinforcement for polyurethane nanofibers exhibits a high elongation at break (500 %), conductivity (0.4 kΩ/cm), and durability (recovery after 200 tensile cycles). Furthermore, the yarn was used to monitor body language. The results showed distinct fluctuations in resistance in response to subtle changes in expression and small movements of the body. In addition, the composite yarn was examined as a potential electric heater material. The yarn’s surface temperature rised to 62.6 °C in 5 s, which proved its excellent electrothermal properties, and it could be realized even at 1 V. The combination of highly conductive structural components, i.e., silver nanowires and the flexible polyurethane nanofibers is a promising design strategy for producing new multifunctional composites for wearable devices.