Abstract This study presents the fabrication and investigation of humidity sensors based on orange dye (OD) and polyaniline (PANI) composite film. The blend of 3 wt % OD with 1 wt % PANI was prepared in 1 ml of water. The composite films were deposited on glass substrates between pre-deposited silver electrodes. The gap between electrodes was 45 µm. The sensing mechanism is based on the impedance and capacitance variations due to the absorption/desorption of water vapors. It is observed that with increase in relative humidity (RH) from 30% to 90%, the impedance decreases by 5.2 x 104 and 8.8 x103 times for the frequency of 120Hz and 1 KHz respectively. The impedance-humidity relationship shows more uniform change as compared to capacitance-humidity relationship in the range of 30 to 90% RH. The consequence of annealing, measuring frequency, response and recovery times, and absorption-desorption behavior of the humidity sensor are also discussed in detail. Annealing results in increase in sensitivity up-to 2.5 times, while the measured response and recovery times are 34 and 450 second respectively. The impedance-humidity relationship was simulated.
Received: 05 January 2012
Published: 10 April 2012
Cite this article:
Orange dye-polyaniline composite based impedance humidity sensors 0 Chin. Phys. B 0 0
