The MQ-137 is an Ammonia（NH3）gas sensor from Winsen. The sensing element is SnO2, which has lower conductivity in clean air. When NH3（Ammonia）gas exists, the sensor's conductivity gets higher along with the gas concentration rising. A simple circuit makes measuring this change in conductivity and turning it into data fairly straight-forward, but does require some calibration.
For easy Solderability; use our Gas Sensor Breakout Board.
