Thin film humidity sensor based on porous titania

The effect of introducing pores in undoped and potassium doped TiO2 thin films on their humidity sensing characteristics was studied. Films were prepared by the set-gel technique. Different potassium compounds were used to introduce potassium ions into the sols that were used for preparation of samples. The influence of these compounds and of the film firing temperature on sample morphology, and on the electrical properties of TiO2 thin films were also studied. Introduction of the porosity in thin films had a positive effect on the humidity sensing characteristics of the samples. Sol-gel processed, porous, and 10 at% potassium doped TiO2 thin films heated to 450 degrees C exhibited an outstanding humidity sensitivity over the entire RH range.