MQ-8 - Hydrogen Gas Sensor

Description of MQ-8 Hydrogen Gas Sensor

MQ-8 is a Metal oxide semiconductor (MOS) type sensor from the series of MQ gas sensors (MQ-2, MQ-3, MQ-4, and so on). The module is highly sensitive to Hydrogen gas and can be used to detect any leaks or presence of Hydrogen gas in the air.

 

Features and Specifications of MQ-8 Hydrogen Gas Sensor

Below mentioned are some of the features and specifications of a Hydrogen gas sensor:

1. Operating Voltage: 5V DC
2. Detects H2 Gas concentration in air
3. Resistant to LPG, smoke, alcohol
4. Heater power consumption: < 800mW
5. Can detect H2 gas in the concentration range of 100 to 1000ppm

 

Alternatives for MQ-8 Hydrogen Gas Sensor

MICS 5524, MQ-2, SGAS701

 

Equivalent for MQ-8 Hydrogen Gas Sensor

MQ-136

 

Note: More technical information can be found in the MQ-8 Sensor Datasheet linked at the bottom of this page.

 

Pin Configuration of MQ-8 Hydrogen Gas Sensor

The MQ-8 gas sensor has 4 pins. The table below describes the pin type and the function of the specific pin.

Pin type	Pin Description
VCC	voltage input for Module(+5V)
GND	GROUND
DOUT	Digital Signal Output
AOUT	Analog Signal Output

Note: There are two different color modules of MQ-8 sensor modules whose pinouts are different;

Blue colored module: VCC, Ground, Dout, Aout

Black colored module: VCC, Aout, Dout, Ground

Usually, the pinouts are marked on the module, so be careful while connecting the sensor module to an MCU/MPU. The connections of the module can be followed from the section below.

 

Connecting MQ-8 gas sensor with MCU/MPU

The MQ-8 sensor can be easily connected to an MCU/MPU using a few jumper wires. As mentioned earlier, the module has 4 pins.

The power pins which are the VCC and ground of the sensor module are to be connected to the 5V and the Ground pin of the MCU/MPU, respectively. For the output signal, the sensor module has analog and digital output pins. The analog output pin of the sensor module is to be connected to the analog pin of the MCU whereas the digital pin of the sensor module is to be connected to a digital pin terminal on the MCU. The gas sensor module also has a potentiometer at the bottom side, to vary the sensitivity of the detection module.

Note: You should always allow some time for the sensor to pre-heat before reading the output data.

 

Working of an MQ-8 Hydrogen Gas Sensor

A gas sensor can detect the concentration of a specific gas in the air. Depending upon the concentration of the gas, the sensor generates a potential difference by changing the resistance of the sensing element, which can then be measured as the output voltage. MQ-8 hydrogen gas sensor consists of a sensing element which is aluminum-oxide-based ceramic, coated with tin dioxide (SnO2), enclosed in a stainless-steel mesh. In the case of any H2 in the air, the resistivity of the sensing element changes, and the change is measured to get the concentration of the gas present. MQ-8 sensor can detect H2 in the concentration range of 100-1000ppm.

 

Applications of MQ-8 Hydrogen Gas Sensor

Below are some of the applications for the MQ-8 gas sensor:

1. Detect leakages in the industry
2. Used in mines
3. Can be used in refrigerators and AC

 

2D Model of the MQ-8 Hydrogen Gas Sensor

2D model of the hydrogen gas sensor module is shown in the image below, The dimensions are in millimeters and can be used to design custom footprints for the gas sensor.