Electrochemical sensor (liquid electrolyte) working principle:
Electrochemical sensors - work by reacting with the measured gas and generating an electrical signal proportional to the gas concentration.
A simple type of sensor that works on electrochemical principles is the two-electrode system. Its working electrode and counter electrode are separated by a thin layer of electrolyte and connected to the external circuit through a small resistance. When the gas diffuses into the sensor, an oxidation or reduction reaction is carried out on the surface of the sensitive electrode, and a current is generated and flows through the two electrodes through an external circuit. The magnitude of this current is proportional to the gas concentration and can be measured by the load resistance of the external circuit.
Advantages and disadvantages of electrochemical sensors:
Advantages: fast response, good linear output, etc.
Disadvantages: It needs a certain oxygen (1-10%VOL) environment to detect, and liquid electrolyte needs to be consumed during use. Easily interfered by temperature, humidity, pressure, and gases with similar chemical properties. If there is a mixed gas on site, it is necessary to consider the problem of interference.
Typical electrochemical sensor specifications:
(1) Sensor type: 2 or 3 electrodes, usually 3 electrodes.
(2) Range: 2-10 times the allowable exposure limit
(3) Life expectancy: normally 12 to 24 months, depending on manufacturer and sensor
(4) Temperature range: –40°C to 45°C
(5) Relative humidity: 15-95%, no condensation
(6) Response time: < 50 seconds
(7) Long-term offset: down 2% per month
List of commonly used electrochemical sensors to detect gases:
