The gas sensing material used in the MQ131 ozone gas sensor is tin dioxide (SnO2), which has a low conductivity in clean air. When there is ozone gas in the environment where the sensor is located, the conductivity of the sensor increases with the increase of the ozone gas concentration in the air. The change in conductivity can be converted into an output signal corresponding to the gas concentration using a simple circuit.

The MQ131 ozone gas sensor has high sensitivity to ozone, and also has a certain sensitivity to strong oxidizing gases such as chlorine and nitrogen dioxide, and reacts in the opposite direction of ozone to organic interfering gases.