MQ135 Air Quality Gas Sensor Module

MQ135 Air Quality Gas Sensor Module 

The MQ-135 Air Quality Gas Sensor Module is a semiconductor gas sensor board used to detect a range of air pollutants and harmful gases. It employs a sensitive tin dioxide (SnO?) sensing element whose resistance changes in response to gases such as ammonia (NH?), nitrogen oxides (NOx), alcohol, benzene, smoke, and other harmful VOCs (volatile organic compounds). The module includes an integrated heater to maintain the sensing element at its optimal operating temperature and provides an analog output that varies with gas concentration, making it easy to interface with microcontrollers like Arduino, ESP32, or Raspberry Pi (with ADC). It’s commonly used in air quality monitoring systems and environmental sensing projects.

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 Features

• Detects air pollutants and harmful gases, including VOCs (e.g., ammonia, benzene, NOx), alcohol, smoke, and more
• High sensitivity to a range of gases
• Analog output proportional to gas concentration
• Requires integrated heater for stable operation
• Simple interface with microcontrollers (ADC required)
• Compact, low-cost sensor suitable for prototyping and embedded systems
• Long operational life

Typical Applications

• Indoor air quality monitoring (homes, offices, classrooms)
• Environmental and pollution sensing
• Smart home air quality alerts
• HVAC system monitoring and control
• Portable air quality detectors
• Industrial environment air monitoring
• Educational and hobbyist electronics projects
• Embedded and IoT air sensing applications