One-Step and Spontaneous in Situ Growth of Popcorn-like Nanostructures on Stretchable Double-Twisted Fiber for Ultrasensitive Textile Pressure Sensor.

Highly conductive fibers play an essential role in the development of electronic textiles for wearable devices. Even though great progress has been made recently, big challenges of developing simple and rapid methods to prepare functional fibers with stretchability, high sustainability, and electrical conductivity still remain. Herein, we proposed a simple, rapid, and scalable approach to fabricate stretchable and conductive fibers by growing Au nanostructures on a double-twisted fiber coated with metallic MoS2 nanosheets. The formation of Au nanostructures with a unique "popcorn"-like shape (namely, Au "nanopopcorn", AuNPC) occurs instantaneously and spontaneously on the surface of MoS2-coated fiber, without any additional reducing reagents or heating conditions. Moreover, the overall fabrication process takes less than 5 min, demonstrating the realization of fast fabrication of functional conductive fibers. The obtained fiber with piezoresistive property can be fabricated into a pressure sensor. The unique morphology of AuNPC with a rough surface can significantly enhance the performance of the pressure sensor, with high sensitivity of up to 0.19 kPa-1 and a fast response time of 93 ms. Furthermore, the functional fiber can be woven into electronic textiles with sensing arrays, which has multiple two-dimensional (2D) force mapping properties. Therefore, we envision that this simple, rapid, and scalable method to fabricate conductive functional fibers would show great potential in the field of electronic textiles and wearable devices.