Humidity sensors based on polyaniline nanofibres

Humidity sensor based on polyaniline nanofibres was fabricated and its response to humidity was investigated. It was found that the sensor behaved differently compared to commonly known conducting polymer based sensors. The sensor responded to low relative humidity (<50% RH) normally by decreasing electrical resistance with increasing humidity. However, at higher RH the sensor reversed its responses by increasing the electrical resistance with humidity. It is believed that the unique structure of nanofibres, which is more susceptible to distortion during polymer swelling, is responsible for the 'reversed behaviour'. IR data confirmed that excess water absorption occurred and that a change in polymer oxidation state might also have taken place.