How a gas sensor works?

Gas sensors” include: Electrochemical gas sensor, Optical gas sensor, Thermal conductivity gas sensor, Semiconductor gas sensor, Contact combustion gas sensor, and so on.

Electrochemical gas sensor:

Principle: Electrochemical methods are used to detect changes in gas concentration.

Working method: The sensing element usually consists of an electrode pair and an electrolyte. When the gas enters the sensor, the charge transfer between the detected gas and the electrodes will change the potential of the electrodes, thus generating a corresponding current or voltage signal output.

Optical Gas Sensor:

Principle: Uses optical principles to detect changes in the characteristic spectral lines of a gas.

Mode of operation: Calculates the gas concentration by measuring the degree of absorption of the detected gas with light of a specific wavelength. The sensing element usually consists of a light source and an optical detector.

Thermal conductivity gas sensor:

Principle: Utilizes the thermal energy generated when the detected gas is excited.

Mode of operation: Gas concentration is calculated by measuring the power required to maintain the temperature of each element. The sensing element usually consists of a thermistor and a heating element.

Semiconductor gas sensors:

Principle: Detection of gas concentration based on the change in resistance of the semiconductor material.

How it works: For example, tin dioxide has a very high resistance in pure air, and when it encounters a combustible gas, its resistance decreases, resulting in a change in voltage that detects the gas concentration.

Contact combustion gas sensor:

Principle: Detects gas concentration by measuring the heat generated by burning the gas inside the sensor.

Mode of operation: Suitable for combustible gas detection, its sensing element will burn when it comes into contact with the combustible gas, and the heat generated is converted into an electrical signal through a thermocouple.

The above classification and principles outline the main technologies of gas sensors. In practice, the choice of gas sensor depends on the type of gas to be detected, the concentration range and the required accuracy.