The humidity dependent conductance of Al2(SO4)3.16H2O

The AC conductivity of aluminium sulphate (Al2(SO4)3.16H2O) 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 ~103-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.