In the last few decades, conductive polymers such as polyaniline, polypyrrole, and polythiophene have been widely
investigated as effective sensitive materials for chemical gas sensors. Among them, polyaniline (PANI) is frequently
used because of its ease and cheap of synthesis, environmental stability and intrinsic redox reaction. However, problems
with these conductive polymers include their low processing ability, poor mechanical strength and chemical stability.
There are tremendous approaches for the enhancement of mechanical strength and chemical stability of organic materials
by combining organic materials with inorganic counterparts in nano-size to form composite materials..which would
optimize the characteristics of gas sensors. In the paper, polyaniline/Indium(III) Oxide(PANi/In2O3) nanocomposite thin
films was prepared on a quartz substrate by combination techniques of electrostatic self-assembly and in situ chemical
oxidation polymerization at 10°C. Infrared spectrum analysis (IR) of the composite and scanning electron
microscope(SEM) of nanocomposite thin films were performed. PANi/In2O3 nanocomposite thin film gas sensor was
fabricated on AT-Cut quartz crystal microbalance(QCM) of Ag electrodes, and the sensitive properties of gas sensor to
CH4 and CO are characterized and analyzed. The results indicate that PANi/In2O3 thin film gas sensor has good linear
sensitive property to CH4 and CO, and is more sensitive to CH4, i.e., the sensitivity is 0.386Hz per ppm when the sensor
is exposed to 500 ppm CH4 while only 0.16Hz per ppm to the same concentration of CO. Such sensitive properties of gas
sensor in the constant concentration of CH4 at different temperature are also characterized. The result shows that
temperature would affect the sensitive property of gas sensor.