MQ136 Semiconductor Sensor for Sulfur Dioxide Sensitive material of MQ136 gas sensor is SnO2, which with lower conductivity in clean air. When the target SO2 gas exist, the sensor’s conductivity is more higher along with the gas concentration rising. Please use simple electrocircuit, Convert change of conductivity to correspond output signal of gas concentration. MQ136 gas sensor has high sensitity to SO2, also could be used to detect other vapor which contains Sulfur. It has low sensitivity to.