We fabricated humidity sensor using nanocubic ZnO/SnO₂ prepared via sol–gel and immersion method deposited on sputtered ZnO-film-coated glass substrate. These combination methods were used to grow nanocubic structured ZnO/SnO₂ at different molar ratios Zn:Sn for the first time. The experiment was conducted at difference molar ratio of Zn:Sn by varying the molar of Zn. The size of the cube reduces as the Zn molar increase. The luminescence of nanocubic structured ZnO/SnO₂ was indicated around 400 and 600 nm corresponding to the ultra-violet (UV) emission and visible emission, respectively. The composition of molar ratio 10:10 of nanocubic structured ZnO/SnO₂ gives the best sensitivity of 104 times for humidity sensor properties. Nanocubic structured ZnO/SnO₂ have a great potential for humidity sensor application with high response (411 s) and recovery times (98 s), repeatability and good in stability.

Unique three-dimensional (3D) titanium dioxide (TiO₂) nanoflowers (TFNA) have shown great potential for humidity sensing applications, due to their large surface area-to-volume ratio and high hydrophilicity. The formation of a composite with other materials could further enhance the performance of this material. In this work, the effect of different types of composites on the performance of a TNFA-based humidity sensor was examined. NiO, ZnO, rGO, and PVDF have been explored as possible composite pairing candidates with TiO₂ nanoflowers, which were prepared via a modified solution immersion method. The properties of the composites were examined using field emission electron spectroscopy (FESEM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) analysis, Hall effect measurement, and contact angle measurement. The performance of the humidity sensor was assessed using a humidity sensor measurement system inside a humidity-controlled chamber. Based on the result, the combination of TiO₂ with rGO produced the highest sensor response at 39,590%. The achievement is attributed to the increase in the electrical conductivity, hydrophilicity, and specific surface area of the composite.