Synthesis and Fabrication of Graphite/WO₃ Nanocomposite-Based Screen-Printed Flexible Humidity Sensor

The resistive type of graphite/WO₃ nanocomposite-based humidity sensor is fabricated through screen printing on a flexible polyethylene terephthalate substrate. Three different nanocomposite-based humidity sensors have been fabricated and analyzed for their humidity-sensing characteristics. The structure elucidation of the nanocomposite was carried out using x-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. By exposing the printed humidity sensor to relative humidity ranging from 11% to 97% at room temperature, its capabilities were studied. The relative resistance, sensitivity, dynamic response, and hysteresis were determined for all three devices, and they showed maximum responses towards relative humidity changes with the highest sensitivity of ≈ 60.8% and excellent hysteresis curves (maximum change of ≈ 1%). The screen-printed flexible humidity sensor exhibited less than a 5% change in the internal electrical resistance when subjected to various bending angles.