Ultrahigh performance humidity sensor based on layer-by-layer self-assembly of graphene oxide/polyelectrolyte nanocomposite film

A ultrahigh performance humidity sensor based on graphene oxide (GO)/poly(diallyldimethylammonium chloride) (PDDA) nanocomposite film was reported in this paper. The multilayered film of GO/PDDA was fabricated on a polyimide substrate using layer-by-layer self-assembly technique. The structures of the self-assembled films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The humidity sensing behaviors of the film sensor were investigated at room temperature over a wide range of 11-97% relative humidity. Unprecedented response of up to 265,640% was demonstrated for the presented sensor when exposed to varying relative humidity levels, which is better than that of the best conventional humidity sensor. Furthermore, the presented sensor exhibited ultrafast response and recovery times capable of monitoring human breath. Moreover, the possible humidity sensing mechanism of the proposed sensor was discussed by using complex impedance spectra and bode diagrams. This measurement results observed highlight the layer-by-layer self-assembled graphene oxide/polyelectrolyte film is a candidate material for constructing humidity sensors.