An Overview about MQ-2 Sensor
The MQ-2 smoke sensor is the metal oxide semiconductor sensor. Hence, also recognized as a Chemiresistor. The MQ2 sensor can quickly detect Alcohol, propane, LPG, hydrogen, and methane. The operating voltage of the sensor is about 5V. Since it requires a warm-up, therefore, it has a preheat duration of 20 seconds. We can use it both as a digital or analog sensor. The sensor is compact and simple to access.
Internal Structure of MQ-2 sensor
They enclose the sensor in two layers of fine stainless steel mesh which is known as an Anti-explosion network. It assures that the heater element inside the sensor will not cause an explosion. The sensing element forms the star-shaped structure. Six connecting legs expand beyond the Bakelite base. From those six legs, two leads heat the sensing element and are connected through the well-known collective alloy called Nickel-Chromium coil. The remaining four legs are actually responsible for output signals. They made the sensing element from Aluminum Oxide (AL2O3) and have a coating of Tin Dioxide (SnO2), which is sensitive to combustible gases.
Working Principle of MQ-2
The working principle of the MQ-2 sensor is based on the resistor. When it detects smoke or fire, the value of its resistance changes. That’s how the gas or smoke gets detected. The sensor works on a very low voltage of around 5Volts. The given potentiometer can change the sensitivity of the digital pin, it draws a current of 500mA.
Features of MQ-2 Sensor
- Operating Voltage is +5V
- Can Measure or detect LPG, Alcohol, Propane, Hydrogen, CO and even methane
- Analog output voltage: 0V to 5V
- Digital Output Voltage: 0V or 5V (TTL Logic)
- Preheat duration 20 seconds
- Can be used as a Digital or analog sensor
- It can vary the Sensitivity of Digital pin using the potentiometer
- Wide detecting Scope
- Fast response and High sensitivity
- Stable and long life Simple drive circuit
Pinout of MQ-2 Sensor
| Pin Name | Pin Number | Description |
| Vcc | 1 | Power Pin requires an operating voltage of 5V. |
| GND | 2 | Ground pin. |
| DO | 3 | Digital out the pin, to get the digital output from the sensor. |
| AO | 4 | Analog out the pin. It based the output of this pin on the intensity of the gas. |
Applications
Air Quality Monitor
Air Quality Monitoring analyzes multiple environmental parameters of the surroundings and therefore is the brilliant solution for controlling the specific smoke gases. It uses the MQ-2 sensor and is thus great to detect methane, Alcohol, Smoke, and Propane.
Gas Leak Alarm
The goal of detecting a gas leak is to prevent the worst potential causes of the gas leak, using the above-mentioned type of MQ sensor. The choice of the MQ-2 sensor is because of the nature of MQ-2 which is suitable for detecting combustible gases and smoke. Also, it is simple integration with other IoT elements.
