High performance humidity sensors based on electrospinning CuO nanofibers on GZO/glass substrates

This research proposed high-performance CuO nanofibers-based humidity sensors. The CuO nanofiber was prepared through electrospinning and calcination processes, and then the mixture was drop-cast on GZO thin films coated on glass substrates. The calcined CuO nanofibers demonstrated a rough surface and had many nanoholes that were beneficial to the captured water molecules. The diameter of the calcined CuO nanofibers ranged from 107 to 288 nm. After X-ray diffraction analysis, the calcined nanofiber had a monoclinic structure of CuO. GZO thin films with interdigitated electrodes formed by ultraviolet laser patterning. The performance of the 12 %-CuO nanofibers-based humidity sensor exhibited the highest sensitivity of 0.752 MΩ/%RH. Furthermore, the 12 %-CuO humidity sensor measured at a frequency of 20 Hz had the largest variation range. The maximum hysteresis and response/recovery time were about 5.69 % at 43 % RH and 1.5/10.2 s, respectively. This indicated that the sensor demonstrated small hysteresis and a rapid response and recovery speed. In addition, the sensor had a discernible dynamic response under different RHs and good repeatability. The impedance RSD was 2.27 %, 7.79 %, and 6.25 % as the sensor was measured at 11 %, 54 %, and 97 % RHs, respectively, revealing good long-term stability. The proposed sensor was applied in functional applications of non-contact switches and hygrometers.