MQ-135

MQ‑135 Gas Sensor – Advanced VOC & Ammonia Detection

The MQ‑135 is a low‑power, high‑sensitivity gas sensor based on a zinc oxide (ZnO) ceramic substrate. It detects volatile organic compounds (VOCs) and ammonia (NH₃), making it ideal for indoor air quality monitoring, greenhouse gas detection and industrial safety applications. The sensor requires a 5 V supply, draws only a few milliamps, and communicates via an analog output that is proportional to the logarithm of the target gas concentration.

Designed for quick response (≈3 s) and long‑term stability, the MQ‑135 incorporates a built‑in heater capable of maintaining the optimal operating temperature (≈400 °C) for reliable gas adsorption. Its small footprint (30 mm × 26 mm) and low cost make it suitable for embedded systems and IoT platforms.

• Key Spec 1: Sensitivity: 200–2000 ppm VOCs (range 200–10 000 ppm for NO₂)
• Key Spec 2: Operating Temperature: 5–10 V, 4.5–10 mA (heater 200–500 mW)
• Key Spec 3: Response time: 3 s (rise), < 1 s (fall)
• Common Use Case: Indoor air quality sensors, smart HVAC systems, safety alarms in laboratories or industrial facilities