Humidity-Sensitive Properties of Titania Films Prepared Using the Sol-Gel Process

TiO2 films, as well as powders as reference, were prepared using the sol-gel process, using titanium isopropylalkoxide (TIPT) as a precursor. The films were deposited on glass slides and heated either to 300°C or to 500°C. The morphology of the film surface was observed using scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) at different relative humidities were carried out to study the possibility of using sol-gel processed titania films as detecting elements in humidity sensors. A good resistance versus relative humidity (rh) sensitivity was observed in the range from 50% to 85%rh. The response time of titania films was rather fast, estimated in a few seconds.