High-performance humidity sensor based on graphitic carbon nitride/polyethylene oxide and construction of sensor array for non-contact humidity detection

This paper presented a novel flexible humidity sensor and sensor array based on graphitic carbon nitride/polyethylene oxide (g-C3N4/PEO) hybrid film with excellent performances. The nanostructure, morphology and composition characteristics of the g-C3N4/PEO nanomaterial were characterized through scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) method. The humidity sensing performances were tested under 11–97 % RH at 20 °C and the experimental results revealed that g-C3N4/PEO humidity sensor has ultrahigh response, fast response/recovery behavior, excellent repeatability and outstanding long-term stability. The humidity sensing mechanism of g-C3N4/PEO nanomaterial was further explained through complex impedance spectroscopy (CIS) and bode diagrams. This proposed high-performance humidity sensor could be applied in practical applications such as human breath monitor under different states, finger approaching and skin moisture detection. Meanwhile, a 4 × 4 sensor array was also fabricated to monitor the approaching of fingertips and identify wet objects with specific shape demonstrating great application potential of the g-C3N4/PEO humidity sensor in non-contact systems.