Sensing behaviors of polypyrrole sensor under humidity condition

The influence of temperature (0, 25, and 40 degrees C and relative humidity (5, 10, and 20%) of polypyrrole (PPy) sensor were studied. The PPy sensors were prepared by chemical oxidative method. Initial resistance of the PPy sensor was increased with increase of humidity and decrease of temperature, respectively. Each sensitivity to methanol, water vapor, and mixture gas (methanol and water vapor) was measured, and then compared. Methanol and water vapor were recognized to different type gases in PPy sensors, and adsorption of methanol and water vapor was competed on the surface of sensors. The sensitivity was increased under low humidity and low temperature. The fastest response and recovery time was shown at 25 degrees C. The reproducibility of PPy sensor was excellent at various humidity conditions. The best operating temperature was investigated at 25 degrees C. (c) 2005 Elsevier B.V. All rights reserved.