Advantages: It has advantages in measuring trace oxygen.
Basic principle: The fuel cell oxygen sensor is composed of a highly active oxygen electrode and a lead electrode, and is immersed in the KOH solution. Oxygen is reduced to hydroxide ions at the cathode, and lead is oxidized at the anode. O2+2H2O+4e4OH 2Pb+4OH 2Pb(OH)2+4e KOH solution is separated from the outside by a layer of polymer film, the sample gas does not directly enter the sensor, the fuel cell oxygen analyzer therefore the solution and the lead electrode are not Need regular cleaning or replacement. The oxygen molecules in the sample gas diffuse through the polymer film to the oxygen electrode for electrochemical reaction. The current generated in the electrochemical reaction depends on the number of oxygen molecules diffused into the oxygen electrode, and the diffusion rate of oxygen is proportional to the sample gas. Oxygen content, in this way, the output signal size of the sensor is only related to the oxygen content in the sample gas, and not to the total amount of gas passing through the sensor. Through the connection of an external circuit, the charge transfer in the reaction, that is, the magnitude of the current is directly proportional to the oxygen participating in the reaction. The fuel cell oxygen analyzer uses this method to measure oxygen, which is not affected by the reducing gas in the measured gas, eliminating many sample gas processing systems. Fuel cell oxygen sensors are completely maintenance-free.
Weakness: Consumable, the fuel pool needs to be replaced regularly.