Cryo‐spun encapsulation of polyaniline‐based conducting hydrogels with high sensitivity, wide‐range linearity, and environmental stability for fibrous strain sensors

Abstract

Abstract Wearable strain sensors are widely engaged in the fields of soft robotics, health monitoring, and human‐machine interfaces. However, low sensitivity, poor environmental resistance, and low‐air permeability of wearable strain sensors severely limit their practical applications. Herein, a coaxial fiber consisting of a polyvinyl alcohol/polyaniline hydrogel (PPH) core and a thermoplastic elastomer (styrene‐isoprene‐styrene block copolymer, SIS) sheath was fabricated by a cryo‐spun encapsulation strategy. The as‐obtained PPH@SIS fiber exhibited high stretchability (>200% strain), large conductivity (0.51 mS.cm −1 ) and high‐yet‐linear sensitivity (gauge factor of 2.4) when being directly used as a fibrous strain sensor. The resultant PPH@SIS fibrous strain sensor showed a stable response at a broad temperature range from −50 to 50°C to various strains (0% ~ 100%) and frequencies (0 ~ 2 Hz). As a demonstration, the PPH@SIS fibrous strain sensors are capable of identifying fast and slow bendings of dummy joints, showing excellent wearability, high sensitivity, and wide detecting range. This work therefore provides a unique cryo‐spun encapsulation strategy for fabricating coaxial conductive fibers promising for wearable sensors with high sensitivity, excellent wearing comfort, and resistance to extreme environments.