G. Sberveglieri et al., AN AL2O3 SENSOR FOR LOW HUMIDITY CONTENT - CHARACTERIZATION BY IMPEDANCE SPECTROSCOPY, Sensors and actuators. B, Chemical, 32(1), 1996, pp. 1-5
A sensor able to measure very low humidity concentrations and with pos
sible applications for geophysical research has been developed using A
l2O3 porous thin films. The sensor is obtained by anodization in sulph
uric acid of an Al thin film deposited by d.c. sputtering. The electri
cal properties are evaluated using impedance spectroscopy for differen
t contents of water vapour in the range 20 to 200 ppmv and for tempera
tures from -60 to +40 degrees C. The response of the sensor changes ac
cording to the frequency of the applied voltage. These results allow u
s to formulate a hypothesis on the mechanism of water absorption.