Fabrication of a flexible single-yarn NH3 gas sensor by layer-by-layer self-assembly of graphene oxide

Abstract

Abstract A novel flexible textile-type NH3 gas sensor was fabricated by the layer-by-layer self-assembly (LBL-SA) of graphene oxide (GO) on a single yarn. A poly(allylamine hydrochloride)(PAH)/poly(4-styrenesulfonic acid) sodium salt (PSS/PAH) bilayer (precursor layer) was deposited LBL on single-yarn substrate. Then, monolayer (GO/PAH) and GO multilayer (GO/PAH)n (n = 2, 3) thin films were self-assembled LBL on a (PSS/PAH)/yarn substrate. The thin films were analyzed by scanning electronic microscopy (SEM). The key step in the operation of the sensor was ion transport, which increased the conductivity of the (GO/PAH)n/PSS/PAH thin films. The electrical properties of the LBL self-assembled GO thin films were studied as functions of the concentration of NH3 gas, to elucidate the effects the number of (GO/PAH)n bilayers on the gas sensing properties (response and linearity). The single-yarn NH3 gas sensor that comprised the (GO/PAH)1 thin film was most sensitive at room temperature. The sensing linearity, response and recovery times, selectivity, bending and humidity effects were also investigated.