Introduction to the working principle and application of gas sensors

Introduction to the working principle and application of gas sensors

Gas sensor is a device for measuring gas, which can convert the type and concentration of the measured target into electrical signals in a specific environment. There are semiconductor gas sensors, optical gas sensors, contact combustion gas sensors, surface acoustic wave gas sensors and electrochemical gas sensors.

The working principle of gas sensors

The wave velocity and frequency on the surface of acoustic devices will drift with changes in the external environment. A gas sensor utilizes this performance to coat a layer of selectively adsorbed gas sensing thin film on the surface of a piezoelectric crystal. When the gas sensing thin film interacts with the gas to be measured (chemical, biological, or physical adsorption), causing changes in the film quality and conductivity of the gas sensing thin film, the frequency of the piezoelectric crystal's surface acoustic wave shifts; Different gas concentrations result in varying degrees of variation in the quality and conductivity of the film layer, resulting in varying variations in the frequency of surface acoustic waves. By measuring the frequency variation of surface acoustic waves, accurate changes in the concentration of reactive gases can be obtained.

The main applications of gas sensors

The main applications of gas sensors include: detection of carbon monoxide gas, detection of gas, detection of coal gas, detection of Freon R11 and R12, detection of ethanol in exhalation, detection of human oral and halitosis, etc.

It converts the information related to the type of gas and its concentration into electrical signals. Based on the strength of these electrical signals, information related to the presence of the gas to be tested in the environment can be obtained, which can be used for detection, monitoring, and alarm. It can also form an automatic detection, control, and alarm system with an interface circuit and a computer. Due to the diverse types and properties of gases, it is impossible to detect all types of gases with one sensor; Therefore, there are many types of sensors that can achieve gas-electric conversion, and the most commonly used ones are semiconductor gas sensors.