Application for Gas Sensor
The application of gas sensor mainly includes: detection of carbon monoxide gas, detection of gas gas, detection of gas, detection of Freon, detection of ethanol in exhalation, detection of bad breath in human body, and the like. It converts the gas type and its concentration-related information into electrical signals. According to the strength of these electrical signals, information about the presence of the gas to be tested in the environment can be obtained, so that it can be detected, monitored, alarmed, and passed through the interface. The circuit and computer form an automatic detection, control and alarm system. Due to the wide variety of gases and the different properties, it is impossible to detect all types of gases with one type of sensor. Therefore, many types of sensors that can realize gas-electric conversion can be classified into semiconductor and non-semiconductor according to the materials constituting the gas sensor. At present, the most practical use is the semiconductor gas sensor. Therefore, this paper mainly describes the related principles and applications of semiconductor gas sensors.
The semiconductor gas sensor detects the gas by utilizing changes in physical properties such as electrical conductivity when the gas to be tested is in contact with the surface of the semiconductor. According to the semiconductor and gas interaction changes are limited to the surface of the semiconductor or deep into the semiconductor, can be divided into surface control type and body control type, the former semiconductor surface adsorption of electrons between the semiconductor and the semiconductor, resulting in the conductivity of the semiconductor When the physical properties change, but the internal chemical composition does not change, the latter semiconductor reacts with the gas to change the internal composition of the semiconductor and change the conductivity. According to the physical characteristics of semiconductor changes, it can be divided into resistive and non-resistive types. When a sensitive semiconductor material is used to contact a gas, its resistance value changes to detect the composition or concentration of the gas. It is based on the adsorption and reaction of the gas, so that some of its relationship characteristics are changed without direct or indirect detection of the gas, such as diode volt-ampere characteristics and threshold voltage changes of the field effect transistor to detect the gas to be measured.
