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Full analysis of the working principle of gas sensors: from electrochemistry to optics
Date: 2025-12-15Read: 0
Gas sensors are core components used to detect specific gas components and their concentrations in the environment, and are widely used in fields such as industrial safety, environmental monitoring, smart homes, and medical health. According to different detection principles, mainstreamgas sensorIt can be divided into electrochemical type, semiconductor type, infrared (optical) type, catalytic combustion type, photoacoustic spectroscopy type, etc., and their working mechanisms have their own characteristics.
Electrochemical gas sensors generate a current signal proportional to the concentration of the target gas through oxidation or reduction reactions on the working electrode. This type of sensor has high sensitivity and good selectivity, and is commonly used to detect toxic or oxygen gases such as CO, H ₂ S, O ₂. However, its lifespan is limited and it is greatly affected by temperature.
Semiconductor gas sensors (such as metal oxide semiconductors, MOS) work based on the principle of gas adsorption causing changes in material resistance. When a reducing or oxidizing gas comes into contact with a heated sensitive membrane, the conductivity changes, resulting in an output signal. Its advantages are low cost, fast response, and suitability for household alarms, but it is susceptible to temperature and humidity interference and has cross sensitivity issues.
Infrared (NDIR) gas sensors are based on the absorption characteristics of gas molecules towards specific wavelengths of infrared light. The infrared light emitted by the light source passes through the gas chamber, and the detector measures the absorbed light intensity, calculating the gas concentration through the Beer Lambert law. This technology has high stability and long lifespan, and is particularly suitable for detecting gases with infrared absorption characteristics such as CO ₂ and CH ₄. It is widely used in HVAC and carbon emission monitoring.
In addition, catalytic combustion sensors are mainly used for combustible gas detection, measuring concentration by detecting changes in platinum wire resistance caused by gas combustion on the catalyst surface; The emerging photoacoustic spectroscopy (PAS) sensor uses pulsed light to excite gas and generate sound waves, which are detected by a microphone to achieve high-precision trace gas analysis.
With the development of MEMS technology, nanomaterials, and artificial intelligence,gas sensorIt is evolving towards miniaturization, low power consumption, multi parameter fusion, and intelligent calibration. Understanding the working principles of various sensors is helpful for scientific selection in practical applications, ensuring the accuracy and reliability of detection.