All About MQ Series Gas Sensor

All About MQ Series Gas Sensor


Are you looking for a blog that provides a detailed explanation of gas sensors and the MQ series of gas sensors, along with their applications? If your answer is Yes! Then check out this blog post which gives you a comprehensive overview of the MQ series of gas sensors, including the MQ-2, MQ-3, MQ-4, MQ-5, MQ-6, MQ-7, MQ-8, MQ-9, MQ-131, MQ-135, MQ-136, MQ-137, MQ-138, and MQ-214. This blog post also explains what 1 ppm (parts per million) means and how it is used to measure the concentration of gases. It then goes on to describe each of the MQ series gas sensors and their applications, which will be helpful for anyone interested in understanding the fundamentals of gas sensing technology.

What is a Gas Sensor?

Determining leakage is crucial in industries, residences, and workplaces since dangerous gases harm the environment. A typical human nose has 400 scent receptors, allowing humans to detect over 1 trillion different odors. But most of us cannot determine the kind or quantity of gas in our atmosphere.  This is where sensors come to mind, using the specified gas sensors it is easy to determine the leakage of gas. 


What is a gas sensor


There are different types of sensors according to the gas, these types of sensors are used to locate and classify various gases. They are frequently employed to estimate gas concentrations and identify explosive or dangerous gases. In other words, a series of sensors known as MQ gas sensors (mq sensor) are used to determine a variety of gases, including alcohol, smoke, methane, LPG, hydrogen, NH3, benzene, and propane. These sensors consist of an electrode that has a sensing substance placed on top and is heated to increase its reactivity and sensitivity. When the type of gas is in the range, these electrodes determine by decreasing the resistance.


Types of Gas sensors

The gas sensors are divided into different series depending on the gas or application. These are

Series of Gas

Purpose/Type of gasses

MQ - 2

Methane, Butane, LPG, smoke

MQ - 3

Alcohol, Ethanol, smoke

MQ - 4

Methane, CNG Gas

MQ - 5

Natural gas, LPG

MQ - 6

LPG, butane gas

MQ - 7

Carbon Monoxide

MQ - 8

Hydrogen Gas

MQ - 9

Carbon Monoxide, flammable gasses

MQ - 131


MQ - 135

Air Quality (CO, Ammonia, Benzene, Alcohol, smoke)

MQ - 136

Hydrogen Sulfide gas

MQ - 137


MQ - 138

Benzene, Toluene, Alcohol, Acetone, Propane, Formaldehyde gas, Hydrogen

MQ - 214

Methane, Natural gas

What is 1ppm equal?

The quantity of gas by volume in the air is referred to as concentration when measuring gases like carbon dioxide, oxygen, or methane. 1 ppm can stand in a variety of ways depending on the chemical being tested. The preferred units for expressing ppm are milligrams per kilograms (mg/kg), microliters per liter (L/L), and micrograms per litre (g/L). a better illustration

The ratio of specified gas to another gas is expressed in the parts-per-million (abbreviated as ppm).  For instance, If you are considered to measure methane at 1 parts-per-million, one molecule would be methane other molecules would be some other gas present in the atmosphere.

ppm = 1/10,00,000 = 0.0001%


Short description and features of each gas sensor

MQ2 gas sensor

The MQ2 gas sensor is an electronic device that is used to detect various types of gases, including hydrogen (H2), liquefied petroleum gas (LPG), methane (CH4), carbon monoxide (CO), alcohol, smoke, and propane. It is widely used in both residential and industrial settings to detect gas leaks and prevent potential hazards.

One of the most significant advantages of the MQ2 gas sensor is its high sensitivity and rapid response time, which enables early detection of gas leaks. This capability is crucial, as gas leaks can pose a serious threat to human health and safety, as well as damage equipment and cause environmental pollution.

The MQ2 gas sensor module consists of a sensing element and a circuit board that amplifies and processes the signal. The sensing element is made up of a tin dioxide (SnO2) semiconductor that is sensitive to the presence of certain gases. When gas molecules come into contact with the SnO2 surface, the conductivity of the sensor changes, and the output voltage of the circuit board is modified accordingly.

To adjust the sensor's sensitivity, this is equipped with a potentiometer, which is a variable resistor that allows the user to adjust the reference voltage of the circuit board. This makes it possible to optimize the sensor's performance and detect gases at specific concentrations.


MQ - 2 Sensor Module

MQ - 3 Sensor Module

The MQ3 Gas Sensor module is excellent for detecting gas leaks (in home and industry). It is capable of detecting CO, CH4, Benzine, Hexane, LPG, and Alcohol. Measurements may be made as soon as feasible due to their high sensitivity and quick reaction rate. The potentiometer can be used to modify the sensor's sensitivity. This low-cost semiconductor gas sensor module is very simple to operate and has both analog and digital output. This Gas Sensor module can be used in breathalyzers because it is sensitive to alcohol. Benzine is similarly only weakly sensitive to MQ3 Sensor.


MQ - 3 Sensor Module

MQ - 4 Sensor Module(Methane, CNG Gas)


MQ - 4 sensor module


The MQ-4 Gas Sensor is a quick and dependable natural gas sensor with good sensitivity to propane and butane as well as high sensitivity to natural gas and methane. This low-cost, long-lasting natural gas sensor is frequently used to find gas leaks.


MQ - 5 Sensor Module(Natural Gas and LPG)

MQ-5 Gas Sensor Detectors are highly sensitive and react quickly. The output of the sensor is an analog resistance. Simply provide the heating coil with 5V, add a load resistance, and connect the output to an ADC.


MQ - 6 Sensor Module (LPG, butane gas)

The MQ-6 Sensor is an easy-to-use liquefied petroleum gas (LPG) sensor that can detect airborne LPG concentrations (which are primarily made of propane and butane). The MQ-6 is capable of detecting gas concentrations between 200 and 10,000 ppm. This sensor responds quickly and with excellent sensitivity. The output of the sensor is an analogue resistance. Simply provide the heating coil with 5V, add a load resistance, and connect the output to an ADC.


MQ - 6 Sensor module

MQ - 7 Sensor Module (Carbon Monoxide)

This type of series module is used to determine the CO, which is clean air and has a lower conductivity. It uses a cycle of high and low temperatures to make the detection and detects CO when the temperature is low (heated by 1.5V).

MQ - 7 Sensor module

MQ - 8 (Hydrogen gas(H2))

This module is suitable for determining Hydrogen Gas and can be used to measure concentrations between 100 and 10,000 ppm. Heater drive and measurement circuit implementation are simple. This sensor is built for durability and consistent output. 

MQ - 9 (Carbon Monoxide, flammable gasses)

This module is suitable for determining CO and flammable gases which in clean air have a lower conductivity. When the temperature is low, it detects CO by cycling between high and low temperatures (heated by 1.5V). Both the sensor's conductivity and the gas concentration are increasing. It identifies methane, propane, flammable gases, etc. when the temperature rises (heated by 5.0V) and cleans the other gases as it is adsorbed under low temperature.

MQ - 9 gas sensor

MQ - 131 (Ozone)

The MQ131 gas sensor is a sensitive component and it has a reduced conductivity in clean air. when there is ozone gas. Both the sensor's conductivity and the gas concentration are increasing. Please use a basic electrical circuit to convert the change in conductivity to a signal that corresponds to the amount of gas present.

MQ-131 gas sensor

MQ - 135, Air Quality (CO, Ammonia, Benzene, Alcohol, smoke):

The MQ-135 Gas Sensor can identify dangerous gases and smoke, including ammonia (NH3), sulphur (S), benzene (C6H6), and CO2. This sensor, like the others in the MQ series of gas sensors, has a pin for both digital and analogue output. The digital pin turns high when the amount of these gases in the air exceeds a predetermined threshold. The onboard potentiometer can be used to adjust this threshold value. An analogue voltage that is produced by the analogue output pin can be used to approximatively determine the concentration of various gases in the atmosphere.

MQ - 135, Air Quality sensor

MQ - 136 (Hydrogen Sulfide Gas)

The MQ136 Gas Sensor can be used to keep track of hydrogen sulphide gas concentrations. The sensor's conductivity increases and the concentration of the target hydrogen sulphide gas rise when it is present. High sensitivity to hydrogen sulphide and low sensitivity to other flammable gases characterize the MQ136 gas sensor. It is inexpensive and appropriate for a variety of uses.

MQ - 137 (Ammonia)

The conductivity of the sensor increases along with the concentration of NH3 gas when it is present. A simple circuit can be used by users to translate changes in conductivity into the corresponding output signal of gas concentration. The MQ137 gas sensor is very sensitive to NH3 gas and has good monitoring capabilities for organic amines like trimethylamine and calamine. It is a type of inexpensive sensor for many purposes that can detect different gases, including ammonia. It has many advantages including a long lifespan, low cost, a straightforward drive circuit, and strong sensitivity to NH3 gas over a wide range.

MQ - 138 (Benzene, Toluene, Alcohol, Acetone, Propane, Formaldehyde gas, Hydrogen)

The conductivity of the sensor increases as the gas concentration does. Through a straightforward circuit, users can translate the change in conductivity to the corresponding output signal of gas concentration. Toluene, acetone, alcohol, and methanol are highly sensitive to the MQ138 gas sensor, which also performs well when monitoring hydrogen and other organic vapours. It is a type of inexpensive sensor for various applications and is capable of detecting different organic gases. It offers benefits including a long lifespan and low cost,  and it has good sensitivity to organic vapour gas over a wide range.

MQ - 214 (Methane and Natural Gas )

Methane (CH4) gas sensor MQ-214 displays its reading as an analogue voltage after detecting the levels of methane in the air.  These gas sensors can identify gases that, are in high concentrations. Detectable concentration: 500–10,000 parts per million for LPG and propane, 1000–20,000 for methane, and 500–10,000 for hydrogen.


In this blog post, we have learned that the MQ Series of gas sensors is the real deal when it comes to sniffing out gases in all kinds of situations. These are equipped to detect even the tiniest amounts of gas, making them a cost-effective and dependable choice for safety purposes. Whether you're concerned about the quality of the air around you, need to spot hazardous gases, or want to make sure your industrial equipment is running safely, the MQ Series has got your back. So What are you waiting for? Don't miss out on the opportunity to harness the awe-inspiring power of the MQ Series gas sensors. They're the ultimate answer to safeguarding your environment and ensuring a healthy, safe, and productive future.


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Frequently Asked Questions

1. What are MQ gas sensors?

MQ gas sensors are known to identify a variety of gases that permeate the atmosphere. Their mode of operation entails the assessment of the electrical resistance of the sensing medium, which inevitably alters upon the infiltration of a targeted gas. These sensors are frequently employed in various scenarios such as air quality surveillance, safeguarding in industrial environments and regulation of vehicular emissions.

2. What is the purpose of a gas sensor?

The gas sensor is engineered to perceive the elusive presence and varying intensities of diverse gases in the atmosphere. This wondrous contraption serves the noble purpose of apprising people of the potential hazards that lurk within their environment, such as toxic carbon monoxide or volatile natural gas. Gas sensors are ubiquitous in industrial and residential domains alike, and perform the crucial role of ensuring the security of the occupants and averting untoward mishaps. Truly, the gas sensor is a technological marvel that defies all semblance of mundanity.

3. What are the advantages of gas sensor?

Gas sensors have an amazing capability to swiftly detect and measure the number of specific gases that exist in the environment around us. This data can be utilized to flag potential hazards to our well-being, like toxic or flammable gases, and to provide us with the necessary alert systems for leaks or other hazardous situations. The applications of gas sensors are ubiquitous - they are found in medicine, ecology, and manufacturing to observe air quality, quantify gas concentrations, and regulate processes. Moreover, these sensors can be incorporated into cutting-edge home automation systems to give us a heightened sense of security and peace of mind.

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