Graphene-coated nylon nonwoven for pressure sensing application

Graphene-coated textiles have attracted great interest in recent years for the development of advanced piezo-resistive materials. In this work, rGO (reduced graphene oxide) treated nylon nonwoven is prepared by the dip coating method. The influence of treatment parameters viz. graphene oxide (GO) concentration, sodium dithionite (Na2S2O4) concentration, and, pH of GO dispersion on rGO add-on and electrical conductivity is analysed and optimized by using Box-Behnken response surface design to prepare electroconductive nylon nonwoven for pressure sensing application. An rGO add-on of 9.12% and surface resistivity of 3.62 k & OHM; sq(-1) have been achieved after two dippings at the optimized dipping condition viz. 0.6% GO concentration, 2 pH, and 15 mM Na2S2O4 concentration. Surface resistivity of 3.62 k & OHM; sq (-1) is achieved after two dippings at the optimized dipping condition with the rGO add-on of 9.12%. The piezoresistive properties of this fabric are investigated. Resistance and thickness of rGO-coated nylon nonwoven treated fabric show a strong negative correlation with the applied pressure. A maximum gauge factor of 2.56 is observed which is in line with pure compression-based pressure sensors. A high-pressure sensitivity of - 0.34 kPa (-1) is observed at 2 kPa pressure with a recovery time of 1.2 s implying that it can be used for pressure sensing. After rGO dipping, bending rigidity, bending modulus, and breaking strength of nylon nonwoven are increased whereas the breaking elongation decreased. Bending rigidity, bending modulus, and breaking strength of nylon nonwoven increase after rGO dipping, while breaking elongation decreases. Surface resistivity and rGO add-on of treated nylon nonwoven remain unchanged even after multiple washing, rubbing, and atmospheric ageing. Nylon nonwovens are characterised by FT-IR, XRD, Raman, FESEM, and LEICA image analyser analysis are used to characterise the developed nonwovens.