The MQ131 is a gas sensor designed to detect ozone (O₃) concentrations in the air. It operates on the principle of resistive change, where the sensor's resistance varies based on the presence of ozone. This analog output can be used to measure ozone levels, making the MQ131 an essential component in air quality monitoring systems.
The MQ131 sensor is available in two variants: low concentration and high concentration. Below are the key technical details for both variants:
Parameter | Low Concentration Variant | High Concentration Variant |
---|---|---|
Detection Range | 10 ppb to 2 ppm | 1 ppm to 10 ppm |
Heater Voltage (VH) | 5V ± 0.2V | 5V ± 0.2V |
Load Resistance (RL) | Adjustable (typically 10kΩ) | Adjustable (typically 10kΩ) |
Heating Current (IH) | < 120 mA | < 120 mA |
Preheat Time | ≥ 24 hours | ≥ 24 hours |
Operating Temperature Range | -20°C to 50°C | -20°C to 50°C |
Humidity Range | 20% to 90% RH | 20% to 90% RH |
Output Signal | Analog voltage | Analog voltage |
The MQ131 sensor module typically has 4 pins. Below is the pinout description:
Pin | Name | Description |
---|---|---|
1 | VCC | Power supply input (5V) |
2 | GND | Ground connection |
3 | AOUT | Analog output signal, proportional to ozone concentration |
4 | DOUT | Digital output signal (threshold-based, requires onboard potentiometer tuning) |
Below is an example of how to connect and read data from the MQ131 sensor using an Arduino UNO:
// MQ131 Ozone Sensor Example with Arduino UNO
// Connect AOUT to A0 pin on Arduino for analog readings
// Ensure the sensor is preheated for at least 24 hours before use
const int MQ131_AOUT = A0; // Analog output pin connected to A0
float sensorValue; // Variable to store the sensor reading
void setup() {
Serial.begin(9600); // Initialize serial communication at 9600 baud
pinMode(MQ131_AOUT, INPUT); // Set AOUT pin as input
}
void loop() {
// Read the analog value from the sensor
sensorValue = analogRead(MQ131_AOUT);
// Convert the analog value to a voltage (assuming 5V reference)
float voltage = sensorValue * (5.0 / 1023.0);
// Print the raw sensor value and voltage to the Serial Monitor
Serial.print("Raw Sensor Value: ");
Serial.print(sensorValue);
Serial.print(" | Voltage: ");
Serial.print(voltage);
Serial.println(" V");
// Add a delay for stability
delay(1000); // Wait 1 second before the next reading
}
No Output Signal:
Inaccurate Readings:
Fluctuating Output:
Digital Output Not Triggering:
Q: Can the MQ131 detect gases other than ozone?
A: The MQ131 is specifically designed for ozone detection. While it may respond to other gases, its sensitivity and accuracy are optimized for ozone.
Q: How long does the sensor last?
A: The MQ131 has a typical lifespan of 2-3 years under normal operating conditions. Proper maintenance and usage can extend its life.
Q: Can I use the MQ131 outdoors?
A: Yes, but ensure the sensor is protected from extreme weather conditions and operates within the specified temperature and humidity range.
Q: Why is preheating necessary?
A: Preheating stabilizes the sensor's internal structure, ensuring accurate and consistent readings. Skipping this step may result in unreliable measurements.