Electrochemical sensor consists of 2, 3 or 4 electrodes, which are located in a gel electrolyte. A system of electrodes and the electrolyte is separated from the atmosphere by a diffusion barrier. Gas molecules diffuse through this barrier and react with the electrolyte. There are oxidation and reduction reactions at the electrodes and they cause a change of cell potential. The higher the gas concentration is, the higher the potential will be.
Reliable and non-expensive sensors for „common“ gases
Long response time (up to few minutes for some gases)
Higher price for special gases
Potential failure when exposed with high concentrations
Cross interferences (ozone sensor is sensitive to air flow, temperature and humidity changes)