Humidity-Responsive and Self-Healable Conductive PEDOT:PSS-Based Hydrogel Fibers for Multifunctional Wearable Sensors

Conductive hydrogel fibers have demonstrated their promising applications in wearable devices due to their distinct advantages, including mechanical flexibility, high conductivity, and wearability. However, the damage to a section of the fibers may affect the operation and applications due to the fibers requiring additional weaving and cycle applications. In this study, humidity-responsive and water-enabled self-healing poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS)/carboxymethyl cellulose sodium (CMC-Na)/poly(vinyl alcohol) (PVA) composite conductive hydrogel fibers (named as PPCP) have been successfully synthesized via a wet-spinning technique. The introduction of [BMIM]BF4 ionic liquids (ILs) and a small amount of Mn2+ in an ethanol/water coagulation bath system greatly enhances the spinnability and the properties of subsequent fibers. The resultant PPCP2 fibers not only exhibit high conductivity (37.6 ± 1.6 S·cm–1) and good flexibility (158.2 ± 3.9%) but also possess humidity responsiveness in the relative wide humidity range (40–90% RH, GF = 1.18) and water-enabled self-healing ability. These features not only satisfy the demands of human health monitoring but also suggest potential applications in water-enabled healing wearable fabrics. Consequently, as a proof of concept, assembled PPCP2 fibrous sensors demonstrate an excellent responsive property to monitor human movements and respiratory patterns, indicating their potential as multifunctional sensors for applications in biosensors and intelligent soft robotics.