thin Al2O3 porous layer grown on an SiO2/Si substrate. The sensor is prepared by sputter
deposition of a thin film of Al, followed by its anodic oxidation in a sulphuric acid solution. A
gold electrode is deposited on the substrate tilted at a grazing angle with respect to the
substrate plane. The electrical ac measurements are made in the range 100 Hz-15 MHz and
in a small chamber where either the relative humidity or the temperature could be easily …