Amperometric gas sensors operate by reacting with the measured gas and generating an electrical signal proportional to the gas concentration. A typical amperometric gas sensor consists of a sensing electrode (or working electrode) and a counter electrode, separated by a thin electrolytic layer.
The gas is dispersed through the reverse side of the porous membrane into the sensor's operating electrode, where it is oxidized or restored, and this electrochemical reaction causes an electric current to flow through the external circuit. In addition to measurement, it is necessary to amplify and perform other signal processing; The outer line maintains the voltage through the sensor and a two-electrode reverses the voltage of the sensor. In the reverse electrode an opposite reaction occurs. In this way, if the working electrode is oxidized, the opposite electrode is restored.
As a low-power and high-sensitivity sensor, the electrochemical gas sensor mainly measures oxygen and various toxic gases, and is widely used in confined space scenarios. What should we pay attention to when using electrochemical gas sensors?
Note 1: Soldering cannot be used during installation
Soldering is a welding method that uses a metal solder with a low melting point to penetrate and fill the gap between the joints of metal parts after heating and melting, and is widely used in the electronics industry. However, soldering cannot be used in the case of electrochemical gas sensor installations.
Reason 1: The outer package of the electrochemical gas sensor is made of plastic material, and the temperature is very high during soldering, which simply deforms the sensor shell and forms electrolyte leakage.
Reason 2: In the high-temperature environment, the heating wire inside the electrochemical gas sensor will form a maintenance oxide film on the surface, and the oxide film will age after a period of time, forming a cyclic process of continuous generation and damage, and the internal elements of the heating wire will be continuously consumed, and the wire will be broken very simply.
Reason 3: The electrolyte inside the electrochemistry is a solvent that can carry out the electrolytic reaction and transfer the ionic charge to the electrode, and the high temperature will damage the internal electrolyte, so that the electrolyte will evaporate and cause sensor damage.
The correct way to install the device: solder the pins to the circuit board first, and then insert the sensor into the circuit board.
Note 2: Do not remove the breathable film on the gas sensor
The vent is a white film above the gas sensor that covers the sensor cover or the top of the electrodes, provides mechanical support for the sensor, and filters out some unwanted particles. The gas can enter the sensor through the breathable film, and the breathable film does not need to be removed when used.
Correct use: Save the white breathable film on the gas sensor and install it on the circuit board.
Note 3: Do not remove the tension spring on the pin
When you get the electrochemical gas sensor, you will find that the two pins of the sensor are connected together by the tension spring, and you will want to remove the tension spring, which is not right, and the tension spring connecting the two pins of the electrochemical gas sensor plays the role of short circuit. When the amperometric gas sensor is not in use, there will be charge accumulation at both ends of the electrode, and the short circuit will release the charge to ensure the charge balance and reduce the aging time of the sensor.
Correct use method: When the gas sensor is not in use, the tension spring needs to be saved, and when used, the tension spring needs to be removed and installed on the circuit board.
Precautions 4: Do not place in an oxygen-free environment for a long time
If the sensor is placed in an oxygen-free environment for a long time, the recovery time will be extended when it is used again, which will affect the application.
Correct placement method: When the electrochemical gas sensor is stored, it is necessary to pay attention to the existence of organic gases and other interfering gases, and whether the ventilation facilities in the environment are good to ensure that the sensor is in clean air.
Note 5: Sensor storage environment
The white breathable film on the sensor, also called the hydrophobic film, is not only dustproof and breathable, but also has a certain isolation effect to prevent electrolyte leakage. However, since this film is not completely sealed, water vapor can easily enter the sensor, and prolonged exposure to high humidity conditions can lead to excessive moisture accumulation and leakage, which can also damage the sensor.
Correct use method: Store in accordance with the temperature and humidity range indicated in the manual.
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