A multifunctional coating toward wearable superhydrophobic fabric sensor with self-healing and flame-retardant properties with high fire alarm response

The design of wearable fabric with ultrasensitive fire alarm response and piezoresistive sensor capabilities is urgently imperative to prevent burn injuries to people in the fire accident. Herein, a novel cotton fabric-based piezoresistive sensor comprising hydrophobic waterborne polyurethane, polyphosphazene (PPZ) microspheres encapsulated 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS), and amino-functionalized carbon nanotubes (A-CNTs) was proposed via a roll coating approach, which achieve self-healing, flame-retardant property, and intelligent fire alarm response. The fabric sensor exhibited prominent flame retardancy because of the synergistic formation of a dense flame-retardant layer on the fabric surface by A-CNTs and PPZ. The char residue of the fabric sensor reached 20.4 wt% at 800 °C, and the limiting oxygen index was as high as 27.4 %. Interestingly, benefiting from the thermoelectric characteristic of A-CNTs, the fabric sensor triggered the fire alarm system within 2 s. More importantly, since the resistance changed with their deformations, the fabric sensor can also monitor a variety of human motions, and its sensitivity (GF) can reach 4.79. Additionally, the resulting fabric sensor exhibited self-healing performance. After physical damage, under near-infrared light irradiation, the healing agent FAS spontaneously migrates towards the surface of the fabric, effectively restoring the superhydrophobic property of the fabric. This work provides new insight into the design and application of multifunctional fabric sensors.