MQ-135 is a low-cost analog gas sensor. It is used in air quality control equipment for buildings and offices. It is suitable for detecting of NH3,NOx, alcohol, Benzene, smoke, CO2 and other dangerous gases. MQ-135 gas sensor module has 4 pins: VCC (requires 5V), GND, Analog output (recommended for more accurate results) and Digital output. All demonstrations in the video are reading the analog output of MQ-135.
MQ-135 has a built-in heater that provides the required work environment for the sensor. The heater operates at 5V. There is a sensitive layer which has lower conductivity in clean air. The sensor’s conductivity gets higher as the gas concentration rises.
The gas sensitivity requires calibration. It depends on the temperature and humidity influence therefore all demonstrations in this video also include HTU21D temperature and humidity I2C sensor module.
ANAVI Gas Detector is used in all demonstrations in the video. It is an ESP8266-powered, open source, Wi-Fi dev board for monitoring air quality and detecting dangerous gases with MQ-135. ANAVI Gas Detector is a certified open source hardware (UID BG000018) designed with the free and open source software KiCad. The source code is available at GitHub. It is easy to use it: attach MQ-135, mini OLED display and HTU21D temperature and humidity sensor to ANAVI Gas Detector, connect the board to your WiFi and after the "burn-in" procedure you can monitor the air quality.
Detecting Flammable GasesMQ-135 detects flammable gases. The 1st demonstration in the YouTube video show how the conductivity increases when a lighter has been turned on near MQ-135. It is important to note that the sensor detects the flammable gas coming out of the lighter which is invisible, not directly the flame.
Detecting SmokeMQ-135 detects smoke. The 2nd demonstration in the YouTube video show how the conductivity increases and the air is reported as poor when the MQ-135 gas sensor module is near smoke for a burning paper.
Detecting AlcoholMQ-135 detects alcohol. As you can see in the 3rd demonstration in the YouTube video the conductivity increases when the sensor is near alcoholic drinks.
Note: if want to make more precise do-it-yourself breath analyzer please consider using MQ-3 with ANAVI Gas Detector.
Comments