Three-layer core–shell Ag/AgCl/PEDOT: PSS composite fibers via a one-step single-nozzle technique enabled skin-inspired tactile sensors

High sensitivity plays a crucial role in the development of wearable electronic devices. For fiber-based wearable sensors, the sensitivity mainly depends on the conductive properties and surface structure of the fibers. In this work, PEDOT: PSS fibers were firstly prepared by wet spinning, which were subsequently placed in Tollens' reagent with the addition of hydroxyurea for a specific silver mirror reaction, achieving three-layer core–shell Ag/AgCl/PEDOT: PSS composite fibers with an optimal conductivity up to 5.2 × 104 S·cm−1. The resultant composite fibers have extremely fast response time (32 ms) and high sensitivity (5.12 kPa−1), while revealing a pressure-dependent feature. It is worth mentioning that the surface of these composite fibers is not a smooth silver layer, but a layer made of tightly stacked Ag nanoparticles, which contribute to a fast response time, ultra-low detection limit, and bidirectional resistance change. Benefiting from the excellent performance, these fibers have been demonstrated to be used as a flexible sensor in wearable e-textiles. Meanwhile, it is expected to be prepared into next-generation flexible electronics such as bionic arms or artificial intelligence.