The MQ137 NH3 Sensor is a high-performance ammonia gas detection module ideal for use with Arduino, ESP8266, ESP32, and Raspberry Pi. It uses the MQ137 gas sensor to detect ammonia (NH₃) concentrations in the environment. The module provides both analog and digital output signals, allowing flexible integration in IoT, automation, and air quality monitoring systems.
This sensor works based on the change in resistance of the SnO₂ (tin dioxide) layer when exposed to ammonia gas. When ammonia is present, the sensor’s resistance changes, allowing the system to measure the gas concentration accurately.
Key Features of MQ137 NH3 Sensor
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Sensitive to Ammonia (NH₃) Gas: Detects NH₃ concentrations from 5 ppm to 500 ppm.
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Dual Output: Provides both analog (AO) and digital (DO) signals for flexible use.
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Adjustable Sensitivity: Onboard potentiometer allows sensitivity tuning.
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Fast Response and Recovery: Detects ammonia presence within seconds.
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Easy Interface: Compatible with Arduino, ESP32, NodeMCU, and Raspberry Pi.
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Long Life and Stable Performance: Designed for reliable, long-term use.
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Wide Operating Voltage: Works on 5V DC supply.
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Onboard Signal Indicator LED: Indicates detection and power status.
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Compact Design: Perfect for integration in air monitoring and safety systems.
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Low-Cost and Easy to Use: Ideal for beginners and professionals in IoT projects.
Technical Specifications
| Parameter | Specification |
|---|---|
| Sensor Type | MQ137 |
| Target Gas | Ammonia (NH₃) |
| Sensing Range | 5 ppm – 500 ppm |
| Operating Voltage | 5V DC |
| Output Type | Analog (AO), Digital (DO) |
| Preheat Time | 24–48 hours recommended for stable performance |
| Load Resistance (RL) | Adjustable via potentiometer |
| Response Time | <10s |
| Recovery Time | <30s |
| Operating Temperature | -10°C to +50°C |
| Relative Humidity | <95% RH |
| Module Dimensions | Approx. 32mm × 20mm × 22mm |
| Weight | ~8g |
Working Principle
The MQ137 sensor works on the semiconducting metal oxide (SnO₂) principle. The resistance of the sensitive material changes when it comes in contact with ammonia gas molecules. This change in resistance is converted into an electrical signal which can be read by microcontrollers like Arduino or ESP32. The higher the NH₃ concentration, the lower the resistance and hence the higher the output voltage.
Applications of MQ137 NH3 Sensor
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Air quality monitoring systems
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Agricultural and livestock environments (for detecting NH₃)
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Industrial safety and gas leakage detection
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Environmental research and IoT-based air monitoring
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Smart HVAC systems
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Waste management monitoring systems
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Laboratory gas measurement setups
How to Interface MQ137 NH3 Sensor with Arduino
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Connect VCC → 5V, GND → GND, AO → A0 pin on Arduino, and DO → Digital pin (optional).
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Allow the sensor to preheat for 24 hours for accurate readings.
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Read analog values using the
analogRead()function. -
Convert raw analog data into NH₃ concentration (ppm) using calibration curves.
✅ For a detailed tutorial and example code, check out our YOUTUBE on MyTechLearner
Calibration
Before taking measurements, the MQ137 NH3 sensor requires calibration. It should be exposed to known concentrations of ammonia gas to generate a proper resistance (RS/R0) curve. Calibration ensures accurate results in your application.
Package Includes
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1 × MQ137 NH3 Gas Sensor Module
Why Buy from Shektronix?
At Shektronix, we ensure you receive authentic and quality-tested components. Every sensor is tested for performance and packaged safely for reliable delivery across India. We also provide technical documentation, tutorials, and sample Arduino codes for easy integration.
🌍 External Resource (DoFollow Link)
For the MQ137 datasheet and detailed technical documentation, visit the official Winsen MQ137 Datasheet.
🔗 Internal Links
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Explore other Gas Sensors
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Buy Arduino Uno Compatible Board to interface with MQ137
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