The MQ-2 gas sensor board is designed for the detection of combustible gases and smoke using a semiconductor-based sensing element. The sensor responds to LPG, i-butane (C₄H₁₀), propane (C₃H₈), methane (CH₄), hydrogen, alcohol vapors, and smoke within a typical concentration range of 100 to 10,000 ppm. Due to its broad sensitivity, the MQ-2 is suitable for general gas detection and monitoring applications rather than selective gas analysis.

The module operates from a 5 V DC supply and integrates the required heater circuitry for stable sensor operation. Gas concentration is evaluated via an analog voltage output in the range of 0 to 5 V, derived from the change in sensing resistance. In addition, a digital output is provided via an onboard comparator with an adjustable threshold, allowing direct use in alarm or switching applications without external signal conditioning.

After each power-up, the sensor requires a heatup time of approximately 10 to 15 minutes before reliable measurements can be obtained. For initial commissioning, a burn-in period of 48 to 168 hours of continuous operation is recommended to stabilize the sensing element. Following this period, a baseline resistance measurement in clean air should be recorded as a reference value. If the sensor has been powered off for several weeks or longer, repeating the burn-in and baseline procedure is advised to maintain measurement consistency.

The board is equipped with power and status LEDs for visual indication of operation and detection status. For mechanical and layout flexibility, the LEDs may alternatively be soldered on the opposite side of the PCB. Electrical interfacing is provided via a 4-pin 2.54 mm header and a Molex PicoBlade connector, enabling straightforward integration into embedded systems, microcontroller platforms, and gas detection devices.