Interfacing MQ-8 Hydrogen Gas Sensor with Arduino

MQ-8 Hydrogen Gas Sensor

The MQ-8 Hydrogen Gas Sensor Module is designed to detect hydrogen gas in the air. It is widely used in gas leak detection systems, safety equipment, and industrial monitoring where hydrogen gas presence needs to be monitored accurately.

Working Principle of MQ-8 Hydrogen Gas Sensor

The MQ-8 sensor operates based on changes in conductivity of its internal sensing material. When hydrogen gas is present in the environment, it interacts with the sensor surface, causing a measurable change in resistance. This change is then converted into an analog signal readable by a microcontroller like Arduino.

Types of Gas Sensors

MQ-8 Hydrogen Gas Sensor

  • Preheat the sensor to stabilize readings.
  • Detect the presence and concentration of hydrogen gas.
  • Convert the gas concentration into a variable voltage output.

MQ-2 Gas Sensor

  • Heated sensing element reacts to gases.
  • Changes resistance based on gas concentration.
  • Provides analog and digital output for microcontroller interfacing.

Requirements

1. Arduino

2. MQ-8 Hydrogen Gas Sensor Module

3. 100 ohm resistor

4. Jumper wires

Pin Configuration of MQ-8 Hydrogen Gas Sensor

MQ-8 Gas Sensor Module

  • VCC: Connect to +5V on Arduino.
  • GND: Connect to GND on Arduino.
  • DO: Digital output pin (triggers at threshold gas level).
  • AO: Analog output pin (gives proportional voltage based on gas concentration).

Wiring the MQ-8 Gas Sensor to Arduino

To wire the MQ-8 to Arduino, connect the VCC to 5V and GND to ground. The analog output (AO) can be connected to an analog pin (e.g., A0) on Arduino, while the digital output (DO) goes to a digital pin if threshold-based detection is used.

Algorithm

  1. Initialize Components

    • Connect the VCC and GND pins of the MQ-8 sensor to +5V and GND on the Arduino.
    • Connect AO to an analog input pin and/or DO to a digital input pin.

  2. Write the Code

    • Set the sensor pin as INPUT in the setup() function.
    • Read the analog value in the loop() to determine gas concentration.
    • Use conditions to act on high gas readings or trigger alerts.

  3. Display Values or Control Devices

    • Print gas concentration to the serial monitor.
    • Use readings to activate alarms or safety mechanisms.

  4. Test the Project

    • Upload the code to Arduino.
    • Expose the sensor to hydrogen gas and observe readings and alerts.
1// Arduino Code to Interface MQ-8 Hydrogen Gas Sensor (Detects Hydrogen Gas)
2
3const int analogPin = A0;     // AOUT connected to A0 for analog gas readings
4const int digitalPin = 2;     // DOUT connected to D2 for threshold-based detection
5const int ledPin = 13;        // Onboard LED for alert indication
6
7void setup() {
8  Serial.begin(9600);              // Start serial communication at 9600 baud
9  pinMode(digitalPin, INPUT);      // DOUT is an input from the sensor
10  pinMode(ledPin, OUTPUT);         // Configure the LED pin as output
11  Serial.println("MQ-8 Hydrogen Gas Sensor Initialized...");
12}
13
14void loop() {
15  // Read the analog gas concentration value
16  int analogValue = analogRead(analogPin);  // Read the analog signal (0-1023)
17  float voltage = analogValue * (5.0 / 1023.0); // Convert to voltage for easier interpretation
18
19  // Print values to the Serial Monitor
20  Serial.print("Analog Value: ");
21  Serial.print(analogValue);
22  Serial.print(" | Voltage: ");
23  Serial.print(voltage);
24  Serial.println(" V");
25
26  // Optional: Check digital output for gas threshold detection
27  int gasDetected = digitalRead(digitalPin);
28
29  if (gasDetected == LOW) {
30    // When hydrogen gas exceeds a preset threshold, DOUT goes LOW
31    digitalWrite(ledPin, HIGH);  // Turn ON LED to indicate gas presence
32    Serial.println(" Hydrogen Gas Detected!");
33  } else {
34    digitalWrite(ledPin, LOW);   // Turn OFF LED if no gas is detected
35  }
36
37  delay(1000); // Wait for 1 second before taking the next reading
38}
39

Applications of MQ-8 Gas Sensors

  • Hydrogen leak detection
  • Fuel cell monitoring systems
  • Industrial safety systems
  • Smart home gas alarms
  • Battery charging stations
  • Hydrogen-powered vehicle safety

Conclusion

Interfacing an MQ-8 Hydrogen Gas Sensor with Arduino provides a reliable method for hydrogen leak detection in safety-critical environments. With basic wiring and programming, you can build a robust monitoring system to protect homes, labs, and industries.