Nanoporous alumina (γ- and α-phase) gel cast thick film for the development of trace moisture sensor

Nanoporous metal oxide thick film in two phases was fabricated by gel-cast technique to use as trace moisture sensor. High resolution was observed only at 1 kHz frequency in both the phases of alumina. The sensitivity of moisture sensors at sub/low ppm range was estimated on the basis of capacitance, which depend upon the water concentration and frequency of excitation in porous structure of alumina based moisture sensor. The sensitivity towards trace level was confirmed by impedance spectroscopy. FESEM, BET, AFM and XRD techniques were employed for the microstructural characterization. The results are highly encouraging and will be very useful for developing trace level commercial moisture sensor.