ABSTRACT
The importance of maintaining a clean environment and issue related to industrial and home safety makes the development of sensitive, faster, selective gas sensors an important technological task. Probably Seiyama was one of the first few to propose inorganic semiconductor gas in 1962 (Seiyama and Kato 1962). Since then, extensive research has been carried out in this direction. Gas sensors are generally classified on the basis of the type of gas molecule–inorganic material interaction. Gas sensors based on the gas-induced changes in electrical conductivity, permittivity, optical constants, and junction characteristics have been investigated. Some sensors based on the changes in catalytic combustion, field effect transistor, and surface acoustic wave devices have also been reported in literature (Comini et al. 2009). Each type has its own merit and demerits. The choice of a particular type depends on the field of application.
