Sensor technology is one of the significant technical foundations for new technological revolutions and advances of information technology.It is an essential part to achieve automatic control and testing and has involved into all areas of human activities. With the popularization and application of micro-computer and microelectronics technology

new requirements has been put forward on performance

quantity

and application of sensors. More attractions are drawn to the development of new sensors. Advantages and disadvantages of semiconductors

concentration cell

contact combustion

and other types of gas sensors and current applications in the critical fields are listed.Research status and development trend of gas sensors are introduced.