Fabrication and characterization of an ultrasensitive humidity sensor based on metal oxide/graphene hybrid nanocomposite

This paper demonstrated a flexible humidity sensor based on tin dioxide/reduced graphene oxide (RGO) nanocomposite film. The humidity sensor was fabricated on a polyimide substrate with microelectrodes by using a facile one-step hydrothermal route. The hydrothermal synthesized SnO2 nanoparticles and SnO2/RGO hybrid nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The humidity sensing properties of the presented SnO2/RGO nano-hybrid sensor were investigated by exposing it to a broad humidity range of 11–97%RH at room temperature. Compared with traditional humidity sensors, the SnO2 modified graphene sensor demonstrated an ultrahigh sensitivity and a rapid response/recovery characteristic over a full humidity range measurement, highlighting the unique advantages of hydrothermal synthesis for sensors fabrication. Finally, the possible humidity sensing mechanism of the proposed sensor was discussed by using complex impedance spectra and bode diagrams. These observed results demonstrate that RGO modified with metal oxide is promising nanomaterials for constructing high performance humidity sensors in widespread applications.