MQ-135 Air Quality Sensor Harmful Gas Detection Module - Analog & Digital Output
The MQ-135 is a semiconductor gas sensor module designed for broad-spectrum air quality monitoring, detecting gases like NH3, NOx, benzene, alcohol, and smoke. Operating at 5V DC, it provides both analog and digital TTL outputs for easy integration with Arduino, ESP32, Raspberry Pi, and other microcontroller platforms.
Features
- Semiconductor sensor detects NH3, NOx, benzene, alcohol, smoke, and CO2 equivalents.
- Provides both analog voltage and digital TTL output signals for flexible interfacing.
- Requires 24-48 hour initial preheating for stable baseline performance.
- Wide detection range from 10 ppm to 1000 ppm, depending on target gas.
- Operates from -10°C to 50°C for indoor and environmental monitoring applications.
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The MQ-135 gas sensor utilizes a tin dioxide (SnO2) semiconductor sensing element. In the presence of detectable gases, the sensor’s conductivity increases proportionally to the gas concentration. This change is converted into an analog voltage signal, which can be read by an ADC, and a digital TTL signal via a comparator for threshold alarms.
Designed for environmental monitoring, the module requires a stable 5V DC supply for its integrated heater circuit to maintain optimal sensing temperature. Consistent performance and sensor longevity depend on the recommended initial 24-48 hour preheating period to stabilize the sensing element. Its broad-spectrum sensitivity makes it suitable for qualitative air quality assessment rather than precise, gas-specific quantification.
Additional Information
| Weight | 0.005 kg |
|---|---|
| Dimensions | 4 × 5 × 2 cm |













