Fabrication and electrical and humidity-sensing properties of a flexible and stretchable textile humidity sensor

Abstract

Abstract A novel flexible and stretchable textile impedance-type humidity sensor was fabricated by weaving white cotton fabric to form a substrate with a pair of parallel electrodes that were made of conductive yarns, and then spray-coating the as-woven textile substrate with a copolymer of methyl methacrylate (MMA) and [3-(methacrylamino)propyl] trimethyl ammonium chloride (MAPTAC) (poly-MMA/MAPTAC) to form a humidity-sensing film. The effects of the concentration of poly-MMA-MAPTAC on the sensitivity, flexibility and stretchability of the textile impedance-type humidity sensor were studied. The 10 vol.% poly-MMA/MAPTAC-coated textile impedance-type humidity sensor had very high stretchability, high flexibility, wide working range, high sensitivity, acceptable linearity, low hysteresis, fast response/recovery time and long-term stability over a relative humidity (RH) range of 20–90% RH. The humidity-sensing mechanism of the textile impedance-type humidity sensor was explained using complex impedance spectra. The fast Fourier transform (FFT) was used to discriminate between a textile impedance-type humidity sensor under bending and human breath monitoring.