Gas sensor is a kind of gas composition, concentration of information convert can be personnel, instruments, such as computers using information devices! Gas sensors are generally classified as a kind of chemical sensors, although the classified not science.

       "Gas sensor" includes: semiconductor gas sensors, electrochemical gas sensors, catalytic combustion gas sensors, thermal conductivity type gas sensors, infrared gas sensor etc.

        Gas sensors sensor for oxide semiconductor, sometimes in added trace of noble metal as radiosensitizing agent, an increase of gas activation function. For electronic give sex reducing gases such as hydrogen, carbon monoxide and hydrocarbon etc, with n-type semiconductor, to accept electronic sex of oxidation, with gas as oxygen P type semiconductor. Semiconductor with membrane fixed on insulating substrate or porous sinter on made sensor. Gas sensor is divided again semiconductor gas sensors, solid electrolyte gas sensors, contact the burning gas sensors, crystal oscillation gas sensor and electricity patent gas sensors.