Electrochemical gas sensors
These sensors are widely used for the gas detection of toxic gases at the ppm level and for oxygen in levels of % of volume. In its most simple form, the electrochemical sensor has two electrodes, “Sensing” and “Counter: which are divided by an electrolyte thin coat. This may be in a liquid state or in a gel state and recently also in a solid state. The electrolyte is isolates towards the outside through a membrane permeable to gas. Gas enters in the sensor by diffusion, through the membrane, and there is an oxidization reaction (reduction that causes an electrical current directly proportional to gas concentration) if a polarization tension is applied to electrodes.