A Stretchable and Self-Healing Dual-Functional Wearable Sensor Enabled by Wet-Spun Conductive Thermoplastic Nanocomposite Fibers

Continuous monitoring of body movements or physicochemical health indicators by various wearable devices with intriguing geometries has attracted increasing research attention. Among them, fiber-based wearable devices have been intensively investigated due to the ease of fabrication, excellent flexibility and adaptability, and abundant applicable working mechanisms. Although various spinning methods can prepare composite fibers, obtaining highly conductive fibers at high filler-loading fractions has always been difficult. In addition, most synthetic fibers are designed only for specific applications, exhibiting narrow applicability. This work proposed a dual-functional smart fiber-based sensor that could work based on either piezoresistive or electrochemical mechanisms. Through the wet spinning of dopes containing nanosized carbon black and thermoplastic polyurethane, nanocomposite fibers with decent electrical conductivities (2.10 × 102 S m−1 or 4.77 × 10−3 Ω·m), high mechanical stretch abilities and toughness (εmax~2400%, KIC = 61.44 MJ m−3), as well as excellent self-heal abilities (η ≥ 64.8%), could be obtained. Such coupled electromechanical properties endowed the as-synthesized fibers with strain-sensing or biomarker monitoring capabilities based on piezoresistive or electrochemical mechanisms. The proposed novel dual-functional smart fibers demonstrated potential for multifunctional wearable health monitoring devices.