MQ-131 Ozone Gas Detection Sensor Module - 10PPB-2PPM Range, Analog & Digital Output

The module requires a stable 5V DC supply for both logic operation and the integrated sensor heater. Ensure your power source can provide sufficient current (typically 150-200mA) for the heater circuit during the initial preheating period and stable operation.

Connect the module's VCC and GND to your microcontroller's 5V and GND pins. For analog readings, connect the AO pin to an analog input (e.g., A0). For digital threshold detection, connect the DO pin to a digital input pin; the trigger point can be adjusted using the onboard potentiometer.

The extended preheating period is critical for the metal-oxide sensor element to burn off contaminants and stabilize its baseline resistance. For reliable and repeatable measurements, especially at low concentrations, completing this initial conditioning phase is strongly recommended before taking readings.

The MQ-131 is best suited for relative concentration measurements and threshold detection. For precise PPM quantification, individual sensor calibration in a controlled environment with a known ozone concentration source is required, as sensitivity can vary between units and is influenced by ambient temperature and humidity.

The potentiometer adjusts the comparator's reference voltage, which sets the concentration threshold for the digital (DO) output. Turning it clockwise typically raises the trigger point, requiring a higher gas concentration to activate the digital signal, allowing customization for different alarm or control setpoints.