Working principle of gas electrochemical sensor
There are many sub-categories of gas electrochemical sensors:
Gas electrochemical sensor-The concentration cell type gas sensor with electrochemically active gas spontaneously forms concentration electromotive force on both sides of the electrochemical cell. The magnitude of the electromotive force is related to the gas concentration. Successful examples of this type of sensor are automotive oxygen sensors and solid electrolyte carbon dioxide sensors.
The restrictive gas sensor has a sensor that measures the oxygen concentration. Using the principle of the correlation between limiting current and carrier concentration in electrochemical cells, an oxygen concentration sensor is prepared for automotive oxygen detection and molten steel oxygen concentration detection.
Thermal conductivity cell type gas sensor
Each gas has its specific thermal conductivity. When the thermal conductivity of two or more gases is very different, the thermal conductivity can be used to distinguish the content of one of the components. The sensor has been used for hydrogen detection, carbon dioxide detection and high-concentration methane detection.
Disadvantages: This gas sensor has a narrow application range and many limiting factors.
Magnetic oxygen sensor
This is the core of the magnetic oxygen analyzer, and the process of "sensing" has been realized. It is made using the principle that oxygen in the air can be attracted by a strong magnetic field. This sensor can only be used for oxygen detection and has good selectivity. Nitrogen oxides in the atmosphere will have a slight impact. The content of these interfering gases is often very small. The selectivity of the magnetic oxygen analysis technology is almost unique.
Infrared gas sensor
Most gases have a characteristic absorption peak in the mid-infrared region, and the concentration of a certain gas can be determined by detecting the absorption of the characteristic absorption peak.
This sensor used to be a large analytical instrument. In recent years, with the development of the sensor industry based on MEMS technology, the size of this sensor has been reduced from a giant to the size of a thumb. The use of infrared detectors without modulated light sources makes the instrument completely free of mechanical moving parts, thus achieving maintenance-free. Infrared gas sensors can effectively distinguish gas types and accurately measure gas concentration.