Porous ceramic sensor for measurement of gas moisture in the ppm range

A moisture sensor based on porous alumina with interdigited thick film elec trodes has been designed and fabricated to detect and measure concentration of moisture in gases over a wide range. Thin alumina compacts have been ta ken where the surface and penetration effect has been considered during the process of adsorption and absorption of water molecules through pores and grain boundaries. The porous structure of the compacts: have been obtained by controlling the particle size of the powder taken, pore size and distrib ution particularly on the surface by varying the percentage of pore former and sintering temperature. The electrode screen-printed with thick film con ductive pastes and the designing of the electrodes have been optimized to o btain maximum sensitivity. The sensor so obtained is basically planar, poro us and is found to be sensitive in the range 50-100 ppmv level of moisture. The response time of the sensor in ppmv level is less than 4 min and at hi gher concentration of moisture, it shows quasi-linear dependency on moistur e content. (C) 2001 Elsevier Science B.V. All rights reserved.