MQ Gas Sensors – Overview
MQ Gas Sensors
The MQ gas sensor family consists of affordable, widely used semiconductor gas sensors designed to detect various gases. These sensors operate on the principle of chemiresistance, where gas exposure changes the sensor's conductivity, producing an analog output proportional to gas concentration. MQ sensors are popular in DIY projects, air quality monitors, and basic industrial safety systems due to their low cost and ease of use. MQ sensors remain a practical choice for hobbyists and cost-sensitive applications where approximate gas levels are sufficient. The sensors come in two versions: native and Qwiic. The Qwiic version enables the use of I2C connectivity with the board.
Which products is this documentation for?
Native
Butane, LPG & Smoke sensor MQ2 breakout
333102
Alcohol, Ethanol sensor MQ3 breakout
333103
Methane, CNG sensor MQ4 breakout
333104
Natural gas, LPG sensor MQ5 breakout
333105
LPG, Butane sensor MQ6 breakout
333106
CO sensor MQ7 breakout
333107
Hydrogen sensor MQ8 breakout
333108
CO, flammable gases sensor MQ9 breakout
333109
Ozone sensor MQ131 breakout
333110
Air quality sensor MQ135 breakout
333111
Ammonia sensor MQ137 breakout
333113
VOC sensor MQ138 breakout
333114
Qwiic
Butane, LPG & Smoke sensor MQ2 breakout with easyC
333116
Alcohol, Ethanol sensor MQ3 breakout with easyC
333117
Methane, CNG sensor MQ4 breakout with easyC
333118
Natural gas, LPG sensor MQ5 breakout with easyC
333119
LPG, Butane sensor MQ6 breakout with easyC
333120
CO sensor MQ7 breakout with easyC
333121
Hydrogen sensor MQ8 breakout with easyC
333122
CO, flammable gases sensor MQ9 breakout with easyC
333123
Ozone sensor MQ131 breakout with easyC
333124
Air quality sensor MQ135 breakout with easyC
333125
Ammonia sensor MQ137 breakout with easyC
333127
Benzene, Toluene, Acetone, Formaldehyde sensor MQ138 breakout with easyC
333128
Key Features
-
Native version:
- Voltage: 5V
- Dimensions: 22 x 38 mm (0.9 x 1.5 inches)
- Mounting: Two mounting holes for secure attachment
-
Qwiic compatible version:
- Voltage: 3.3V
- Dimensions: 54 x 22 mm (2.1 x 0.9 inches)
- Microcontroller: ATTINY404
- Communication: I2C
- Connector: 2 × Qwiic (formerly easyC) ports (plug-and-play, no soldering needed)
- Mounting: Four mounting holes for secure attachment
You may also need
Qwiic cable
Qwiic (formerly easyC) compatible cables with connectors on both ends, available in various lengths.