Joy-IT SEN-MQ135 Air Quality and Gas Sensor Module

Joy-IT SEN-MQ135 is a versatile air quality sensor module designed for detecting various gases and harmful airborne substances. Based on the popular MQ-135 gas sensor, it is suitable for air quality monitoring systems, smart home applications, IoT devices, industrial automation and educational electronics projects.

The sensor can detect ammonia (NH₃), nitrogen oxides (NOx), benzene, alcohol vapors, smoke, carbon dioxide (CO₂) and other volatile organic compounds (VOC). Featuring both analog and digital outputs, it can be easily integrated with Arduino, Raspberry Pi, ESP32, ESP8266 and other microcontroller platforms.

Real-Time Air Quality Monitoring

The MQ135 sensor enables continuous monitoring of indoor and environmental air quality.

• Air quality measurement
• Early pollution detection
• Suitable for indoor monitoring
• Continuous environmental sensing
• Ideal for IoT applications

Detectable Gases

• Ammonia (NH₃)
• Nitrogen oxides (NOx)
• Carbon dioxide (CO₂)
• Benzene
• Alcohol vapors
• Smoke
• Volatile Organic Compounds (VOC)
• Various harmful gases

Analog and Digital Outputs

The module provides both continuous analog readings and threshold-triggered digital output.

• AO analog output
• DO digital output
• Adjustable sensitivity
• Integrated LM393 comparator
• Easy calibration

Easy Integration

• Compatible with Arduino
• Works with Raspberry Pi
• Supports ESP32 and ESP8266
• Suitable for STM32 platforms
• Standard connection interface

Adjustable Detection Threshold

An onboard potentiometer allows adjustment of the digital output trigger threshold according to application requirements.

• Sensitivity adjustment
• Fast response to gas concentration changes
• Simple system tuning

Applications

• Air quality monitoring stations
• Smart home systems
• HVAC and ventilation control
• Industrial monitoring
• IoT devices
• Environmental monitoring systems
• Educational electronics projects
• Research and development applications

Technical Specifications

• Manufacturer: Joy-IT
• Model: SEN-MQ135
• Sensor Type: MQ135
• Detectable Gases: NH₃, NOx, CO₂, benzene, alcohol, smoke, VOC
• Supply Voltage: 5 V DC
• Operating Current: Approx. 150 mA
• Outputs: Analog (AO), Digital (DO)
• Comparator: LM393
• Sensitivity Adjustment: Yes
• Operating Temperature: -10°C to +50°C
• Operating Humidity: 5–95% RH

Why Choose Joy-IT SEN-MQ135?

The Joy-IT SEN-MQ135 is one of the most widely used air quality sensors for electronics projects. It enables reliable detection of multiple harmful gases, real-time environmental monitoring and seamless integration with popular development platforms. It is an excellent choice for smart home, environmental monitoring and IoT applications.

This analog gas sensor has a small heating part with an electronical chemical sensor.
It is suitable for indoor usage.
The sensor can output exact values only after warmup phase.

Caution: sensor gets hot while usage!

Technical data:

Measurement range: 10 - 1000 ppm

Measureable substances: Benzene (C6H6), Ammonia (NH3), sulfide, smoke, other air pollution

Application areas: Detecting gas leaks, gas alarm, robotic, microcontroller projects

Compatible with: Raspberry Pi (with AD-converter), Arduino. etc.

Special features: High sensitivity, detection of a wide range of concentrations

Analog Output: Values are processed by the microcontroller

Digital Output: thresholds can be set

Pins: VCC: Voltage supply 5V, GND: Ground, AOUT: Analog Output, DOUT: Digital Output

Detection ranges: Ammonia (NH3), Alcohol: 10 - 300 ppm Benzene: 10 - 1000 ppm

Loop voltage: ≥ 24 V DC

Heating voltage: 5.0 V ± 0.2 V

Heating resistance: 31 Ω ± 3 Ω at room temperature

Heating power: ≤ 900 mW

Sensitivity: Rs (in air)/ Rs (100ppm NH3) ≥5

Operating temperature: -10 - 50 °C