A large number of researches on hydrogen sensors have been carried out at home and abroad. At present, H2 sensor mainly fall into three categories: electrochemical, electrical and optical.
In view of the wide use and insecurity of hydrogen in food hygiene, energy power, military and national defense, the concentration of hydrogen must be tested when it is used.
1,Electrochemical hydrogen sensor
Electrochemical H2 sensor is a hydrogen sensor that converts chemical signals into electrical signals to achieve hydrogen concentration detection.
The electrochemical sensor consists of two electrodes, one electrode as a sensing element, the other electrode as a reference electrode.
When hydrogen reacts electrochemically with the sensor electrode, the charge transfer or electrical properties on the electrode change.
The sensor realizes the purpose of hydrogen concentration detection by detecting the change of corresponding physical quantity. Electrochemical hydrogen sensors can be divided into two categories: current type and potential type.
2, electrical hydrogen sensor
The electrical H2 sensor mainly uses the electrical characteristics of the material and hydrogen concentration has a certain functional relationship, through the detection of electrical physical quantity, hydrogen concentration is measured.
According to the different working principles, electrical hydrogen sensors can be divided into resistive and non-resistive.
At present, the market share of electrochemical and electrical hydrogen sensor is high. Various electrochemical hydrogen sensors have wide operating temperature range, low power consumption and high sensitivity.
However, its electrode life is limited, and the work needs to provide current or voltage to the sensor, is not suitable for flammable and explosive places.
3, optical hydrogen sensor
The optical H2 sensor mainly utilizes the optical properties of gas.
According to the different working principles, it is mainly divided into the following categories: fiber optic hydrogen sensor, surface acoustic wave hydrogen sensor, photoacoustic hydrogen sensor.
The fiber optic hydrogen sensor has the advantages of intrinsic safety, electromagnetic interference resistance, small size, corrosion resistance and so on.
And its sensor sensitivity and measurement accuracy is high, can achieve real-time response. According to the different sensing mechanism, a variety of fiber optic hydrogen sensors suitable for single point measurement and distributed multi-point measurement can be fabricated.