The gas sensing material used in the MQ-3B alcohol gas sensor is tin dioxide (SnO2), which has a low conductivity in clean air. When there is alcohol vapor in the environment where the alcohol sensor is located, the conductivity of the gas sensor increases with the increase of the alcohol 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.
MQ-3B semiconductor alcohol sensor has high sensitivity to alcohol and can resist the interference of gasoline, smoke and water vapor. This gas sensor can detect alcohol atmospheres of various concentrations and is a low-cost sensor suitable for a variety of applications.