Facile fabrication of flexible strain sensors with AgNPs-decorated CNTs based on nylon/PU fabrics through polydopamine templates

[Display omitted] •Demonstration of the flexible strain sensor based on the nylon/PU fabric with PDA by a feasible dip-coating process.•The cooperative conductive effect of AgNPs and CNTs-COOH for tunable sensitivity and suitable sensing range of the sensor.•The excellent detection ability of the fabricated sensors to human motions as flexible wearable devices.•The outstanding electrical heating performance of the strain sensors to human joints as wearable electrical heaters. Incorporating conductive materials into the fabric structure for flexible wearable applications has aroused extensive research attention in recent years. Although flexible wearable sensors based on textiles make important strides towards the achievement of flexible wearable devices, most of the reported flexible strain sensors still have some limitations, with special reference to the manufacture of the sensitivity, and durability of these sensors with subtle- and large-scale workable strain sensing ranges on an industrial scale. Herein, a flexible strain sensor was fabricated to generate carboxylated carbon nanotubes (CNTs-COOH) and silver nanoparticles (AgNPs) respectively on the polydopamine (PDA)-templated nylon/polyurethane (nylon/PU) fabric surface via a dip-coating technique and liquid-phase chemical adsorption reduction process. The surface morphology and chemical structure of the fabricated nylon/PU fabric were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Interestingly, CNTs-COOH and AgNPs were successfully coated onto the PDA-templated nylon/PU fabric (PNPF). Furthermore, the as-prepared strain sensor exhibited fascinating performances, containing high sensitivity, suitable stability under different strains, remarkable electrical conductivity because of the depositing of conductive fills, exceptional durability over 1000 cycles, and outstanding electrical heating property. Importantly, the proposed strain sensor was demonstrated to be used for human motion including tiny human movement and robust body motion or temperature detection, indicating its further desirable application in flexible wearable devices.