MG811 Carbon Dioxide Sensor For Carbon Dioxide Detector Module
🧠 What Is MG811?
A gas sensor module designed to detect Carbon Dioxide (CO₂) concentration in air.
Based on a solid electrolyte (electrochemical) sensing principle.
Outputs an analog voltage corresponding to CO₂ levels.
🔍 Key Features
Detects CO₂ gas specifically
High sensitivity to CO₂
Analog output (continuous measurement)
Long lifespan (solid-state sensor)
Suitable for air quality monitoring systems
Requires heating element for operation
📊 Technical Specifications
| Parameter | Value |
|---|---|
| Target Gas | Carbon Dioxide (CO₂) |
| Detection Range | ~350 ppm to 10,000 ppm |
| Operating Voltage | 6V (heater), 5V (module logic) |
| Output Type | Analog voltage |
| Preheat Time | ≥24 hours (recommended for stability) |
| Operating Temperature | –10°C to +50°C |
| Humidity Range | ≤95% RH |
⚙️ Module Components
MG811 sensor element
Heating circuit (for sensor activation)
Signal conditioning circuit (amplifier)
Comparator (in some modules)
🔌 Pin Configuration (Typical Module)
VCC → 5V
GND → Ground
AO → Analog output
DO → Digital output (threshold-based, optional)
🧠 How It Works
The sensor contains a solid electrolyte material sensitive to CO₂.
CO₂ concentration changes the internal voltage/resistance.
The module amplifies this signal.
Outputs an analog voltage proportional to CO₂ concentration.
Microcontroller reads and converts it into ppm values (after calibration).
📐 Output Behavior
Low CO₂ → Lower output voltage
High CO₂ → Higher output voltage
⚠ Output is non-linear → calibration required for accurate ppm values.
📌 Applications
Indoor air quality monitoring
HVAC systems (ventilation control)
Greenhouse CO₂ monitoring
Industrial safety systems
Smart home IoT air monitoring
⚠️ Important Notes
Long Preheat Required: Up to 24 hours for stable readings.
High Power Consumption: Due to internal heater.
Calibration Required: Must calibrate using known CO₂ levels.
Cross Sensitivity: May react slightly to other gases.
Not Highly Accurate: Compared to NDIR CO₂ sensors (like MH-Z19).
🛠 Summary
Type: Electrochemical CO₂ gas sensor
Range: ~350–10,000 ppm
Output: Analog (and optional digital)
Power: Requires heater (higher consumption)
Use Case: Air quality monitoring
