The humidity dependent conductance of Al2(SO4)3.16H2O

The AC conductivity of aluminium sulphate (Al 2 (SO 4 ) 3 .16H 2 O) is found to be strongly humidity dependent. This property has been used to develop a humidity sensor. The AC conductance of the specially designed humidity sensor varies ~10 3 -fold when the relative humidity changes from 22 to 88%. It is observed that the AC conductance of aluminium sulphate varies exponentially with relative humidity between 35 and 70% relative humidity levels. A transducer using aluminium sulphate may be designed for developing a humidity sensor effective between the 35 and 70% relative humidity levels. The effect of frequency on conductance is insignificant in the higher-frequency region.