Abstract
The great concerns regarding environmental and living beings protection together with the widespread requirements for highly accurate process monitoring have highlighted the need for the development of new and sensitive sensors. Conducting polymers and their nanocomposites have been used widely as sensing materials owing to their special redox chemistry. The electrical properties can be controlled easily by doping and undoping processes resulting into the generation of conducting and nonconducting states, respectively. The electrical conductivity also depends on the type and amount of filler (nanosize filler in some cases) used which produces the positive or negative carriers responsible for the conduction. Any type of interaction of these polymers that affects the number and movement of charge carriers affects the conductivity and is the main principle behind the gas sensing characteristics. Advances in nanotechnology allows for the fabrication of various conducting polymer nanocomposites using different techniques. Conducting polymer nanocomposites have high surface area, small dimension, and show enhanced properties, making them suitable for various sensor devices. This chapter presents the different types of gas sensors based on the conducting polymer (polyaniline, polypyrrole, and polythiophene)-based nanocomposites, their progress, and future scope of ongoing research in this research area. The factors that affect the performance of the gas sensors and the chemistry of the sensing process are also addressed.