Zinc tungstate doped polyaniline as room temperature humidity sensing composite

Zinc Tungstate (ZnWO₄) a bi-metal oxide is doped in low concentration to polyaniline (PANI) by 'In-situ' chemical polymerization method to form a composite. The FTIR characterization technique is used to confirm the formation of polyaniline salt phase and its composites. X-RD & SEM characterization techniques are used to verify the existence of ZnWO₄ in PANI matrix. The temperature dependent conductivity shows an exponential behaviour which is thermally activated; the conductivity of the composites has been enhanced by 10 Ohms when compared with pristine PANI. It is reported that electrical resistance decrease, when the composite matrix are exposed to the wide range of humidity from 20 to 90% RH. The decrease of resistance has been recognized as; the chemically adsorbed water vapour donates the electron to the sensing surface in this composite and also due to capillary condensation. (paper)