In situ hydrothermal growth of Cu NPs on knitted fabrics through polydopamine templates for heating and sensing

Incorporating conductive components into fibrous structure for wearable applications has attracted research attention recently. However, utilizing the flexibility and wearability of textiles to maintain a stable and durable wearable performance is a big challenge, as the intrinsic properties of textiles and the conductivity of the incorporated components have to work synergically in the fibrous system without compromising. In this work, polydopamine-templated PET fabrics were prepared to grow copper nanoparticles (Cu NPs) on the surface of the knitted PET fabrics. The surface morphology, chemical composition and crystalline structure of the Cu NP-coated PET fabrics were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The results showed that Cu NP layer was successfully deposited onto the polydopamine-templated PET fabrics. The fabrics showed excellent electrical conductivity due to the loading of Cu NPs. The unique knitted structure together with the durable deposition of Cu NPs resulted in negative change in electrical resistance of the fabrics under strains, granting the fabrics the potential in wearable applications. The Cu NP-coated PET fabrics were demonstrated to be applicable as wearable strain sensors and electrical heaters.