Winsen MQ-4 Methane Gas Sensor Module - Semiconductor Sensor

The MQ-4 sensor's heater requires a stable 5.0 volts, which can be supplied as either AC or DC. This voltage is critical for bringing the SnO2 sensing element to its optimal operating temperature. The module's signal output circuitry is also designed to work with standard 5V microcontroller logic levels.

You can interface the MQ-4 module with an Arduino using either its analog or digital output pins. For analog reading, connect the module's analog output pin to an Arduino analog input (A0-A7) to measure the voltage proportional to gas concentration. For a digital trigger, connect the digital output pin to a digital input pin on the Arduino; this pin goes HIGH or LOW when the gas concentration exceeds a preset threshold, which is adjustable via a potentiometer on the module.

Yes, for accurate quantitative measurement, the MQ-4 sensor requires calibration against known methane concentrations. The sensor's output can drift over time and is influenced by environmental temperature and humidity. For simple presence detection, the factory-set digital threshold may be sufficient, but for reliable ppm readings, periodic calibration in clean air and a known target gas is recommended.

The MQ-4 sensor is specifically sensitive to methane (CH4) but can also respond to other combustible gases, including alcohol vapors, to a lesser degree. Its design offers some anti-interference to alcohol, but high concentrations of other volatile organic compounds (VOCs) or hydrogen may affect the reading. It is best used in applications where methane is the primary gas of concern.