Polypyrrole doped with dodecylsulfate ion on electrochemical polymeriz
ation of pyrrole keeps the anion in it on reduction of the polymer in
an aqueous solution. The free anion on reduction of the polymer attrac
ts a cation to form a salt in the polymer. An attempt was made to use
polypyrrole as a sensing material in measurement of humidity. The gold
covered electrode was constructed by employing a photo-resist method
and the ionic conductivity of the reduced polypyrrole changes from 2 x
10 kOMEGA.cm to 3 x 10(3) kOMEGA.cm depending on humidity.