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Hi readers! Welcome to a detailed exploration of the MQ gas sensor series where we are discussing the basic details of its members. This series was engineered using revolutionary technology to detect combustible and toxic gases with great efficiency. It uses the chemiresistor sensing element to detect the target gas and has a quick response time that makes it a reliable choice. These are used in multiple industries, domestic areas, offices, and other places where a chance of leakage of combustible gas occurs. This series might not be fancy, but it is designed for a long life and ensures minimal false detection for reliable output.

We are going to start the discussion with a basic introduction to this series, and then we’ll try to clear up some basic concepts in order to have the best understanding. The main target of this article is to discuss the gas sensors individually and highlight their distinctive features. You will see each MQ sensor in it, and in the end, we will discuss its working principle and conclude each point. Here is today’s first topic:

What is a Gas Sensor?

A gas sensor is an electronic device that is used for the detection of a particular gas in the surrounding air. In some cases, it also measures the concentration of the target gas. Mostly, these sensors work on the basic chemical reaction of the gas molecules with the internal components. These are some of the most basic elements of the safety system in different industries and systems and are life-saving in different cases. 

Gas sensors come in different sizes and shapes, and usually, these are the parts of a circuit that may include the microcontroller boards. These boards take the information from the gas sensor and control the other members of the circuit. There are multiple series of gas sensors that play crucial roles in different domains, and some important names are highlighted here:

• MQ Gas Sensor Series
• Figaro TGS Gas Sensor Series
• Alphasense B4 Series
• SGX Sensortech MiCS Series
• Winsen Gas Sensor Series

MQ Gas Sensor Series Introduction

The MQ gas sensor series is a popular series that is designed mainly for combustible gases like methane, carbon monoxide, liquefied petroleum gas, alcohol, hydrogen, propane, butane, smoke, natural gas, carbon dioxide, and many others. Each member of this series is designed to detect a particular set of gases. This series is compatible with Arduino and arduino related boards (such as the ESP32) and incorporates different circuits.

The features of this sensor make it one of the most suitable options for all types of users, whether they are students, professionals, or hobbyists, and they can utilize it for different projects. The good thing is, that each sensor is pretty straightforward to install, has a simple structure, works on low power, and is a cost-effective solution to the gas leakage problem. 

MQ Gas Sensor Series Basic Concepts

Prior to exploring the different types, it's essential to establish some fundamental points regarding gas sensors. The detection of the presence of gas is not enough, but gas concentration (quantity of the gas) is a crucial point when measuring gases like carbon dioxide, oxygen, ozone, or methane. Generally, two units are used to measure the gas concentration, the basic introduction of which is given here:

What is the ppm?

The parts per million (abbreviated as ppm) is the ratio of one gas with respect to the other. In simple words, if we are dealing with the concentration of oxygen in the air, then 1000 ppm of O2 in the air means that if we have a million gas molecules, then 1000 out of these are oxygen and the other 999,000 are air. The same concept is applied to different units other than millions, such as:

• Micrograms per cubic meter (µg/m³)
• Milligrams per cubic meter (mg/m³)
• Parts per billion (ppb)
• Milliliters per liter (ml/L)

What is the Percentage Concentration?

Another unit to measure the concentration of gas is the percentage concentration. It refers to the percentage of a particular gas in a mixture of different gases. In simple words, it is the total percentage of 100 in the mixture. For instance, the 20% percentage concentration of carbon mono oxide (CO) in the air means, 20% CO is present in the air and 80% are other gases in a particular area.

In the MQ gas sensor series, usually, the ppm is used to describe the performance of the sensor with respect to the concentration. The relationship between these two units is shown as:

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

MQ Gas Sensor Series Types

As mentioned before, the MQ gas sensor series offers multiple sensors that are associated with a particular group of gases. Here is a list of all the members present in the MQ sensor family:

MQ Gas Sensor Series Detail

Until now, we’ve seen the name and related gas, but each of them has some specific features, so let’s highlight some important points about each of the MQ gas sensor series:

MQ2 Gas Sensor

The MQ2 gas sensor is an electronic device that is used to detect various flammable gases such as methane (CH4), butane (C4H10), liquefied petroleum gas (LPG), and smoke. Because of its wide number of detectable gases, it is equally useful in industries as well as in domestic areas where these combustible gases are widely used for cooking, fuel, or other purposes.

This sensor has a quick response time and a high sensitivity, which make it a good and reliable choice for detecting flammable gases that can pose a serious threat to health and safety. It is a versatile gas sensor and, therefore, is one of the most commonly used sensors in the MQ sensor series.

This sensor is present in two forms: as a standalone sensor or as a module. Another point that highlights its easy-to-use design is the presence of the potentiometer. Through this, the user can set the threshold values to stimulate the digital pin when set. The following table will clearly show all this information:

MQ3 Gas Sensor

The MQ3 is another gas sensor with a wide variety of gas detection capabilities; therefore, it is one of the favorites of multiple users. It detects a wide variety of gases, including alcohol, benzene, methane, hexane, LPG, carbon monoxide, and some others. Some important advantages of this sensor are its fast response time and high sensitivity. This is used in areas where gases are used as fuel and there are high chances of leakage.

This is also present in the form of a standalone sensor or a module. It has a digital output pin; therefore, can be used even without the need of a microcontroller (in simple circuits). It has the potentiometer to set the threshold values. The quick response time makes it suitable for various industries and domestic areas. Here is the table that shows all these features at a glance:

MQ4 Gas Sensor

This sensor from the MQ sensor series has a fast response time and provides a stable output, which makes it a perfect choice for different projects. It can detect natural gas and methane and is a reliable sensor, among other alternatives. The two LEDs in its structure are a special feature of its module that acts as the output lights. The purpose of these lights is explained here:

1. The output at the green light on the module shows that the concentration of the gas is less than the critical level.
2. The output of the red light indicates that the concentration of the target gas is less than the critical value.

Along with these, other features of this module are mentioned in the table here:

MQ5 Gas Sensor

The MQ5 is the sensor from the MQ as a sensor series, particularly designed to detect H2, LPG, CH4, CO, alcohol, smoke, and related gases. The most significant gas in this regard is LPG because MQ5 has the greatest sensitivity for it. Because it has a great sensitivity to flammable gases, it is therefore a crucial component of the safety system in almost all types of places. The module removes the false alarms because it can filter the noise from alcohol, cooking fumes, or cigarette smoke. The small size and easy integration make it a suitable choice for multiple types of projects.

This comes as a sensor as well as a module to fit in different circuits. The module has a buzzer and a potentiometer that allow the user to set the threshold values. In this way, it can be set in such a way as to create an alarming buzzer sound if the target gas concentration exceeds the threshold value. The concentration detection ranges from 200 ppm to 10000 ppm, which is quite wide. It is commonly present in the metal casing and, therefore, has a grey or silver color. All the important features of this sensor are mentioned in the table below:

MQ6 Gas Sensor

The MQ6 gas sensor is a member of the MQ gas sensor series, which is mainly used for the LPG butane (made of butane and propane) gas sensor but has a sensitivity for other gases as well, such as butane, propane, methane, alcohol, hydrogen, and smoke. The fast response time is a remarkable feature of this sensor that makes it a good choice for detecting LPG, among others on the market. It is a cost-effective sensor with a fast response time, so it is a reliable option. Just like other modules in the MQ series, it can also work with the Arduino, and the user simply has to connect its analogue pin with the Arduino circuit.

This sensor has a potentiometer to adjust the sensitivity and is present in the form of a separate sensor or module. Depending on the module or model, it comes in blue or black color. It detects the gas concentration anywhere between the range of 100 ppm to 10000 ppm. Like other sensors from this aries, the MQ6 sensor also has a power range of 5V. Some modules have the digital pin as most of the MQ sensor members. Here is the table that will show you its features at a glance:

MQ7 Gas Sensor

The MQ7 gas sensor is designed to detect carbon monoxide in the air. It has a high sensitivity to the target gas and, therefore, is a reliable device for various circuits. The rapid response time of this sensor (10 seconds) allows it to quickly respond. It works on 5V power, which is very low and makes it a good choice for projects like IoT, where these are powered on continuously. The small size is also a reason for its low power consumption.

The potentiometer is present in its module, and usually, it is present in blue and grey. Just like other sensors, the metallic covering of the sensor’s circuit protects it from unwanted particles of dirt or other substances. It has a sensitivity ranging from 20 to 2000 ppm and is designed to provide a stable output. Other details of this sensor are mentioned in the table of its features:

MQ8 Gas Sensor

Hydrogen is a colorless odorless gas that is flammable even at low concentrations; therefore, early detection of this gas is important. The MQ8 gas sensor is an ideal choice for it because its mechanism is designed to detect hydrogen ranging from 100 to 1000 ppm. It has a sensitivity to other gases as well, such as smoke and LPG, but in these cases, it does not provide the best performance. It has a fast response time and is small, so it may be placed in different circuits.

The operating temperature of this sensor is 5 volts, and it is available at a cheaper rate on the market so can be used in almost all types of projects. It shows the analog and digital output; therefore, it can be used without any need for a microcontroller. The digital output ranges from 0V to 5V and follows the TTL logic. At Atians the stable performance is 20 seconds after it is powered on so is a reliable source for the detection of hydrogen gas. The following table highlights its basic features:

MQ9 Gas Sensor

The MQ9 gas sensor is a reliable source to detect carbon monoxide and some flammable gases. We know that CO is a poisonous gas that hinders the oxygen supply in the body; therefore, its early detection is crucial in areas where the chances of gas leakage are high. Multiple sensors are on the market for CO detection, but MQ9 is preferred because of its low cost and instant performance.

The digital and analog outputs help users consume them for multiple types of projects. The gas detection depends on the change in temperature values. At low temperatures, MQ9 can detect the presence of carbon monoxide whereas when the temperature is high, it successfully detects methane, propane, and other combustible gases. This feature supports its applications in the domestic areas for fuel gas leakage detection.

MQ131 Gas Sensor

The MQ131 gas sensor is specialized to detect the ozone gas around it. It works like the MQ7 and MQ9 gas sensors which means that at low temperatures, it detects the presence of ozone gas, and at high temperatures, the depletion layer around its sensing element is absorbed in the air so it eliminates all other absorbed gases.

The increase in the ozone concentration results in the increase of its conductance and can detect ozone (highly sensitive), CL2, NO2, and some other gases. Here is its table that explains its features:

MQ135 Gas Sensor

The MQ135 is also called the all-rounder of the gas detector because of the wide variety of gases it can easily detect, therefore, it is a solution for multiple industries' gas detection. The basic gases it can detect are NH3, NOx, alcohol, benzene, smoke, and CO2, but it is also sensitive to ammonia, sulfide, smoke, and other harmful gases.

 In some cases, it is considered an air quality sensor because it can detect multiple impurities in the air. Its basic features are mentioned in this table:

MQ137 Gas Sensor

This sensor is designed to detect ammonia (NH3) and carbon monoxide (CO) and belongs to the air quality monitoring category. It has a digital pin, can be connected to the microcontroller, and also has a sensitivity to ozone gas.

It shows a quick response time and is easy to install in the projects therefore, is a good option to be used in the study project as well. Other features can be found in the table below:

Conclusion

The MQ gas sensor series stands as the optimal solution for detecting gas leaks, whether they involve combustible gases or general ones. It is a reliable and versatile solution for the detection of various gases that are alarming for the safety measures of any place. Most of the sensors have a wide detection scope, and after carefully observing all the sensors, I can say most of the sensors have a gas detection range from 10 ppm - 10000 ppm. The sensors are engineered to detect specific gases, yet they possess the capability to detect additional gases, although with reduced sensitivity, owing to their similar internal structure.

The basic structure of these sensors depends on the ceramic tube on which the sensing layer is spread and a heating structure that stimulates the sensing element to absorb oxygen from the air. This produces the depletion layer of oxygen ions and increases its resistance. Once the target gas comes into contact with this region, it initiates a reaction that leads to a reduction in the thickness of the depletion region. Consequently, the conductivity of the sensing element increases, which is reflected in the output signal on the analog pin. If the threshold value is set through the potentiometer, it stimulates the digital pin.

We have seen different members of the MQ series and understood their basic features and working principles. I hope you found this article useful and if you want to learn more, you can ask in the comment section.

Good day peeps! Welcome to another episode of the MQ gas sensor series and today, the topic is the MQ214 natural gas sensor. We know that natural gas is inflammable and is utilised widely for cooking and other purpose in domestic areas as well as a fuel in multiple industries. The leakage of natural gas can be the reason for the accidents and its accumulation may even result in the explosion. Moreover, continuous inhalation of this gas can cause health issues such as nausea, dizziness, and headaches therefore, instant detection of its leakage is crucial. For this, one of the best options is MQ214 because it has a fast response time, low power consumption and is easily available.

In this article, we are discussing the fundamental points about this sensor. We’ll see its basic introduction and will see the basic components to see its features. After that, we’’ go through some points of its datasheet. Following this, we will explore the working principle and physical dimensions of the sensor and consequently, we’ll see some important applications where this sensor is widely used. Let’s move towards the first point:

MQ214 Natural Gas Sensor Introduction

The detection of natural gas leakage is important because every year, multiple accidents are seen because of the undetectable presence of natural gas. The MQ124 is a member of the MQ sensor series which is utilised to detect natural gas (which primarily consists of methane (CH4), in different projects. It has the features like a simple structure, easy installation, instant performance and reliability that make it a popular choice. Moreover, it has a good sensitivity to other gases as well but in this article, our focus is the main target gas (natural gas). Some important gases that MQ124 detects are:

• Carbon Monoxide (CO)
• Methane (CH4)
• Liquefied Petroleum Gas (LPG)
• Hydrogen (H2)
• Alcohol (C2H5OH)
• Smoke

MQ214 Natural Gas Sensor Basic Structure

Now, you will see the important components of this sensor that collectively create the MQ124 natural gas sensor:

MQ214 Natural Gas Sensor Ceramic Tube

The ceramic tube acts as the base for the sensing element and plays a role in the better performance of the sensor. It is made of alumina (Al2O3) and has good thermal and electrical resistance as well as chemical inertness which makes it a perfect choice for this role. This provides mechanical strength to the sensing element and does not cause any change in its performance. 

MQ214 Natural Gas Sensor Sensing Element

Usually, metal oxides are used in such cases because of their chemical properties and in most of the MQ gas sensors, including MQ124, tin oxide (SnO2) is used as the sensing element. It is present in the form of a uniform layer around the ceramic material and absorbs the gases to perform its duty. It acts as the heart of the MQ124 natural gas sensor and provides reliable performance.

MQ214 Natural Gas Sensor Heating Circuit

The sensing element alone can not show the best result until the heating sensor does its work. It raises the sensing element temperature to the optimal range and stimulates it to absorb the gas. The main heating element in this structure is made with the resistant wire (usually made of nichrome. Other components of this circuit are:

• Power supply
• Temperature Control
• Protection Circuitry
• Wiring and Connectors

MQ214 Natural Gas Sensor Housing and Base

The housing and base of the MQ124 sensor serve as both a support structure and a shield, ensuring the circuit's integrity and protecting it against external factors. The following points will help you to understand their role:

• These are made with heat resistance and reliable materials such as plastic, metal, or bakelite that protect the internal circuit from heat and environmental factors.
• The housing encloses the delicate internal structure and acts as a protective barrier against dust, moisture, and other contaminants.
• The housing is perforated and allows the gas only to pass through it.
• Depending on the model of MQ214, the base may have mounting holes or brackets for easy installation.
• In addition to this, the base may also have labels, wire entry points, ventilating points, etc.

MQ214 Natural Gas Sensor Datasheet

The datasheet is an important document that represents the technical information of the devices. Here are some important points that highlight basic information about MQ214:

MQ214 Natural Gas Sensor Features

• It has a high sensitivity to natural gas and, therefore, has a very low response time.  

• It has tin oxide (a metal oxide) for sensing the target gas therefore providing accurate and reliable output. 

• The wide range of 200 to 10000 parts per million (ppm) of this sensor makes it an ideal option for detection. 

• It has adjustable laid resistance.

• This sensor has a temperature range of -10°C to 50°C and shows flexibility in the designing process as well. 

MQ214 Natural Gas Sensor Specifications

The following is the outline of the technical specifications of the MQ214 natural gs sensor:

MQ214 Natural Gas Sensor Sensitivity Characteristics

This sensor can detect multiple gases at a time but has the most sensitivity to natural gas. Here is the sensitivity characteristic graph of this sensor for different gases that shows the comparison:

MQ214 Natural Gas Sensor Temperature/Humidity Curve

The temperature has a major role in the performance of this sensor therefore, always have an eye on the temperature and humidity graph before using it. Here is the graph that will show you its performance at varying temperatures and humidity:

Here,

• Ro shows the sensor resistance at 1000ppm of i-butane in the air at 33% RH by keeping the temperature at 20 degrees.
• Rs shows the sensor resistance at 5000ppm of CH4 at different temperatures and humidities.

If you are interested to know more about the MQ214 datasheet, you can visit the following link:

MQ214 Natural Gas Sensor Pinout Configuration

The pin configuration of the MQ214 Natural Gas Sensor follows the same pattern as other sensors within the MQ gas sensor series. Below is a table presenting all the relevant details:

MQ214 Natural Gas Sensor Packages

MQ214 Natural Gas Sensor Alternatives

The MQ214 is a popular choice for natural gas detection but it has some limitations. if you want to know some alternatives for the Same target gas then here is the list of these:

• Electrochemical Sensors

• Figaro TGS series (e.g., TGS813 for methane)

• Sensirion SGP series (e.g., SGP30 for various VOCs)

• Infrared (IR) Sensors

• Shinyei PPD series (e.g., PPD-420 for methane)

• Metal Oxide Semiconductor (MOS) Sensors (Alternatives to MQ-214)

• Figaro TGS2600 series (wider range of detectable gases)

• Figaro TGS822 (hydrogen-specific)

• Catalytic Bead Sensors:

• Figaro TGS6810 series

As mentioned before, natural gas is mainly methane so the list contains specialized sensors for detecting it. Other sensors can detect multiple gases including methane. 

Where to Buy MQ214 Natural Gas Sensor 

Always get sensitive devices from a reliable source. Here is the list of the sources where millions of products are present with the best quality and price:

• eBay

• AliExpress

• Amazon

MQ214 Natural Gas Sensor Working Principle

The main principle that MQ124 follows when working to detect the target gas is the chemiresitor and it is defined as:

The chemiresistor is the mechanism of the metal oxide gases in which when they absorb a particular gas their electrical resistance increases.

The output on the MQ124 is obtained by following the steps given here:

• When the sensor is powered on, the heating circuit starts its work and the temperature of the sensor increases gradually until it reaches 300 C.
• At this temperature, the sensing element is stimulated to absorb the oxygen from its surrounding air. The chemical reaction creates the oxygen ions and as a result, a thin depletion layer is accumulated around the sensing element.

• The depletion region results in the increase of electrical resistance. The analogue values of this resistance are sent through the analogue pin. At this point, the mQ214 is ready to detect any target gas.
• If there is a leakage of the gas around it, the depletion region around the sensing element starts reacting with it and it results in the absorption of the region. As a result, the electrical resistance change decreases and more current passes through the circuit.
• The sensor measures the conductivity and changes it into an electrical current. The magnitude of this current is directly proportional to the gas concentration. These values are sent continuously to the analogue pin.
• If the threshold value is set before, once reaching it will cause the sensor to send the signal to the digital pin.

As a result of this flow, the target gas, along with its magnitude is sensed through the MQ214.

MQ214 Natural Gas Sensor Physical Dimensions

Below is the table that shows the general dimensions of the MQ214 natural gas sensor. Keep in mind that these may vary from model to model but the typical values are shown here:

MQ214 Natural Gas Sensor Applications

Natural gas is widely used in different domains of life therefore, this sensor has a wide scope. Here are some important projects in these domains that will highlight the importance of this sensor:

• Home Safety and Monitoring

• Smart Home Gas Leak Alarm

• DIY Air Quality Monitor (Combustible Gases)

• Industrial Applications

• Industrial Gas Leak Detection System

• Combustible Gas Level Monitoring for Production Lines

• Environmental Monitoring:

• Portable Methane Detector for Environmental Research

• Community Air Quality Monitoring Network
  

Hence in this way, we have seen the fundamental knowledge about the MQ214 natural gas sensor. We started the discussion with its basic introduction and saw the basic elements that collectively create this sensor. We also saw the important points from its datasheet such as its features, specifications, and some important graphs. The working principle was also discussed in detail here and in the end, we also saw the physical dimensions and applications of this sensor. I hope I have covered all the points but if you are curious in more detail, you can ask in the comment section. 

Hey students! Welcome to another episode of the MQ gas sensor series. Today, we are interested to learn about the high-performance sensor that is used to detect the presence of benzene gas. This is the MQ138 gas sensor and it instantly detects the target gas because it has tin dioxide as the sensing element. Usually, it can detect multiple gases and is considered as the Volatile organic compounds (VOC) sensor but the most significant target gas of this sensor is benzene therefore, we’ll pay attention towards the discussion of the benzene detection through this sensor. Many features of this sensor resemble other members of the MQ gas sensor series and we’ll read its basic features and specifications in detail. 

In this article, we’ll initiate the discussion with the basic introduction of this sensor where we’ll also see its basic components and their purpose. After that, we’ll show you the datasheet elements that will be helpful to understand its technical specifications. You will also see the working principle, physical dimensions and applications of this sensor in different fields as well so stay with us.

Let’s start with the first topic:

MQ138 Benzene Gas Sensor Introduction

The MQ138 is a member of the MQ gas sensor series that is specialised for the detection of benzene gas around it. It works on low voltages and uses tin oxide as the sensing element that is readily available to detect any leakage of the benzene gas in the surrounding air. Mainly, it follows the chemiresistor which is defined as:

"The chemiresistor of an element refers to the mechanism in which its electrical resistance changes when it absorbs the surrounding gas."

The sensing element of MQ138 absorbs the target gas and the change in the concentration is indicated through the analogue values of the sensor.

We know that benzene is used in multiple industries as a fuel as well as for chemical reactions but exposure to this gas is hazardous for humans. If accidentally inhaled for a short time, it can cause the issue issues like dizziness, and headaches and long-term inhalation is even more dangerous and can also cause cancer. These are the points that make the presence of benzene gas sensor systems such as with MQ138 compulsory at such places. 

Let’s see the components of this sensor to know its details:

MQ138 Benzene Gas Sensor Ceramic Tube

There is a small ceramic tube-like piece of alumina (AL2O3) that works as the mechanical support to the sensing element. This ceramic tube has excellent thermal stability as well as resistance to the electrical current therefore, this does not cause any change in the electrical resistance of the sensing element but only provides the mechanical strength. This results in the uniform absorption of the target gas on the evenly spread sensing element it. 

MQ138 Benzene Gas Sensor Sensing Element

The heart of the MQ138 is the sensing element that is made of tin oxide (SnO2). This is present evenly on the ceramic tube and ready to react with the benzene gas if gas is leaked into the air. Tin oxide has less conductivity to the clean air as compared to the air mixed with benzene therefore it is used as the sensing element in such sensors. 

MQ138 Benzene Gas Sensor Heating Circuit

The heating sensor plays a crucial role in sensors like MQ138 because it maintains the required temperature to stimulate the optimum performance of the temperature. This consists of a heating coil made of nichrome wire and gradually increases the temperature of the sensing element. This is a crucial process and whenever the sensor is turned on, the heater circuit gets the 5V power and starts its work. 

MQ138 Benzene Gas Sensor Housing and Base

The circuit of the sensor is delicate and requires protection from outward agencies such as dirt particles in the air. This is done by a perforated metallic cap that covers the whole sensor. It acts like a filter that only allows the gas to pass through it and as a result, the system may perform best for a long time.

Moreover, the whole body of the sensor is made with plastic or bakelite material. The sensor modules have a large base that has multiple items on it such as the power LED, pins, etc but the sensor alone has a relatively simpler structure and the base has pins for the direct connection in the circuit. 

MQ138 Benzene Gas Sensor Datasheet

Prior to employing any device, it is essential to review the device's datasheet so we are discussing some crucial points from the datasheet of the MQ138 benzene gas sensor:

MQ138 Benzene Gas Sensor Features

The MQ gas sensor series has simple and fundamental features and I am highlighting the most basic features of the MQ138 sensor from its datasheet:

• It has a wide detecting scope and a quick response time so is a reliable option.
• It provides stable performance and has a long life so is an affordable sensor.
• It shows the analogue values at its analogue pin that allow the user to see the concentration level of the benzene gas.
• It has a digital pin the values of which can be set through the potentiometer.
• This sensor has electrostatic discharge (ESD) protection which is one of the reasons behind its long life.
• It shows the protection against the overvoltage.
• It has a simple drive sensor and requires 20 seconds for the pre-heating.

MQ138 Benzene Gas Sensor Specifications

The table given below shows the specifications of the MQ138 benzene gas sensor:

MQ138 Benzene Gas Sensor Basic Circuit

The labels of the image given above are explained below:

• VCC: This pin connects to the positive terminal of the power supply which is typically 5V.
• GND: This pin connects to the ground terminal of the power supply to complete the circuit.
• H or Heater: This pin connects to one side of the resistor (RL) which is responsible for limiting the current flowing through the sensor's internal heating coil that is mentioned before in this article.
• RL: This is the load resistor in series with the heating coil. The typical value for the MQ-137 is around 10KΩ which may vary according to the model.
• A or B: These pins are interchangeable and connect to the circuit voltage which is typically 5V.
• OUT or Signal: This is the analogue output pin that provides a voltage signal that varies depending on the benzene gas concentration around the sensor.

If you want to learn more about the datasheet of this sensor in detail then you must see the link that is provided here:

MQ138 Benzene Gas Sensor Pinout Configuration

Till now, we have been discussing the pins and their features at many points but for ease of learning, here is a table that shows the pins, their name, and precise descriptions that will help you to understand this sensor’s pin details:

MQ138 Benzene Gas Sensor Packages

MQ138 Benzene Gas Sensor Alternatives

Multiple other options can be used in place of the MQ138 benzene gas sensor. Some important names in this regard are listed below:

• Electrochemical Sensors (Benzene Specific)
• Benzene-Specific Semiconductor Sensors
• Air Quality Sensors (VOC Detection - Might include Benzene)

Where to Buy MQ138 Benzene Gas Sensor

Always buy sensitive devices like M138 from the well-reputed source and some of such examples are given below:

• eBay
• AliExpress
• Amazon

MQ138 Benzene Gas Sensor Working Principle

Just like the simple structure, the MQ138 benzene gas sensor has the simple way to work. As mentioned before, it follows the chemisterisitor and the details of this are shared in the following points:

As soon as the sensor is powered on, the heating circuit starts it work. It requires 20-25 seconds from the preheating and gradually, the temperature of the sensor reaches 300 Celsius.

• At this temperature, the tin oxide is readily available for the reaction and it starts reacting with the surrounding air (assume it is clean air). At this point, the oxygen ions start accumulating on the surface of the sensing element. This results in an increase in the electrical resistance. These values are sent through the analogue pin.

• The sensor is ready to detect any target gas around it.

• When the target gas is leaked into the air, the oxygen ions from the depletion region react with it and start melting. This results in a decrease in the electrical resistance. 

• The change in the electrical resistance is indicated on the analogue pin and sent to any output device. 

• If the threshold value is set through the potentiometer then when the analogue values reach it, the sensor shows the digital output on the digital pin and this results in the indication of this gas on output gas without any need of a microcontroller. 

• The higher the concentration of target gas around the sensor the more is the magnitude of the analogue value. 

MQ138 Benzene Gas Sensor Physical Dimensions

MQ138 Benzene Gas Sensor Applications

• Industrial Leak Detection

• Occupational Safety Monitoring

• Air Quality Monitoring

• Environmental Remediation

• Indoor Air Quality Monitoring (limited)

• Personal Safety Devices (specialized)

Hence, today, we have seen the detailed information about the MQ138 benzene gas sensor. Our exploration commenced with a fundamental introduction, followed by an examination of the essential components comprising this sensor. We also understood the basic points from the datasheet of this sensor and then moved towards the working principle and through the steps, we understood the detail of how it detects the target gas. In the end, we saw the packages, dimensions, and applications of this sensor. I trust that I covered all the points and if you want to know more, you can ask in the comment section.

Hi readers! Welcome to the next article on the MQ series gas sensors. Today, our motto is to learn about the basic information of the MQ137 ammonia gas sensor. We know that ammonia gas is extensively used in industries, agricultural lands, Environmental Monitoring, Health and Public Safety, etc. In such areas, there are great chances of leakage that can be harmful and here, sensors like MQ137 are used for the instant detection of the Ammonia gas. It is a colorless gas with a distinct pungent smell and its inhalation may cause eyes, lungs, nose, and throat infections and irritation. So, the MQ137 is specialized for its detection and acts as a life savior in such cases. 

In this article, we’ll commence our discussion with the basic introduction of the MQ137 ammonia gas sensor and will learn its basic structure to understand its features. After that, we’ll see some important points from its datasheet such as its specifications and some important graphs related to its performance. We’ll shed light on its working principle and physical dimensions and in the end, you will see the basic fields where this sensor is widely used. Let’s move towards the first point:

MQ137 Ammonia Gas Sensor Introduction

The MQ137 is an ammonia gas sensor designed to detect ammonia gas in various environments. This is available either as a module or as a sensor and can be integrated into appropriate electronic circuits or microcontrollers such as Arduino, ESP32, etc. The module comes with digital and analog pins and here, the digital pin makes it operate even without using the microcontroller with it. 

Ammonia is a hazardous gas for human inhalation and it causes multiple health issues even with minimal exposure. The MQ137 has the sensing element that instantly reacts with the ammonia gas and changes in the analog pin values indicate the concentration of ammonia around the sensor. 

MQ137 Ammonia Gas Sensor Basic Components

The internal structure and components of the MQ136 ammonia gas sensor are similar to other members of the MQ gas sensor series. Here is the list and a little description of each of them:

MQ137 Ammonia Gas Sensor Ceramic Tube

There is a small tube-like structured piece of ceramic material (micro AL2O3) placed on the circuit of the MQ137 ammonia gas sensor. The reason behind choosing AL2O3 is its excellent thermal stability. Moreover, it does not affect the electrical resistivity of the sensing element, and, therefore, does not cause any change in the results. 

This ceramic tube provides mechanical strength to the sensing element layer so provides a uniform reacting area to the target gas. This is crucial for the exact analogue values. 

MQ137 Ammonia Gas Sensor Sensing Element

The MQ137 has the tin oxide (SnO2) for the sensing of a target gas. Here, the sensing element is present in the form of a uniform layer on the ceramic tube as mentioned in the previous point. As a result, the mechanical support helps the tin oxide to be readily available for reaction even at a small concentration of ammonia gas. 

MQ137 Ammonia Gas Sensor Heating Circuit

The heating sensor is responsible for maintaining the sensing element’s temperature. It consists of a nichrome wire coil that heats the circuit continuously at a uniform temperature. This small coil is embedded near the sensing element and ceramic tube.

MQ137 Ammonia Gas Sensor Electrodes

The connection between the sensing layer and ceramic material is made with the electrodes made of usually gold (Au). These are responsible for providing the path for the electrical current to pass through the sensing element. These play a crucial role because the measurement of the sensing element resistance is the main principle of this sensor. 

MQ137 Ammonia Gas Sensor Housing and Base

The whole circuit is protected by the firm base and housing. The housing is made of a perforated metal cover that only allows the gas to pass through it therefore, it filters the unwanted particles to reach the delicate internal circuit.

The connection of these pins will be discussed in the coming sections. The module of M137 uses a strong base made of plastic or bakelite that not only provides strength to the circuit but is provides space for the pins. Some modules have an LED that shows the presence of the gas if detected.

MQ137 Ammonia Gas Sensor Datasheet

The datasheet is a crucial document to learn before using any electrical device like the MQ137 ammonia gas sensor. Here are some key sections of the MQ137 sensor datasheet that serve as valuable resources to enhance your understanding and facilitate informed usage:

MQ137 Ammonia Gas Sensor Features

• It has high sensitivity and, therefore, can detect the presence of ammonia gas even at low concentrations. 

• It shows the analog values for the change in the concentration of the gas which helps represent the exact concentration value of the ammonia gas. 

• The presence of the digital output pin makes it useable even without the integration of the microcontroller. 

• The circuit is designed in such a way that it represents a stable output and reliable performance as compared to many other sensors. 

• The wide range of gas detection allows this sensor to provide versatility in the values and detect the gas at a distance as well. It has a fast response time that makes it more reliable. 

• It has easy integration and is present in the form of different packages to make it usable in different circuits. 

MQ137 Ammonia Gas Sensor Specifications

The table given below has all the important specifications that you must know:

MQ137 Ammonia Gas Sensor Circuit Diagram

As mentioned before, the circuit and structure of this sensor are straightforward. Here is a basic circuit diagram that will help you to understand its structure:

The explanation of each label is given here:

• Vc: Loop Voltage (typically ≤ 24V DC)

• VH: Heater Voltage (typically 5.0V ± 0.1V AC or DC)

• RL: Load Resistance (which is adjustable by VR1)

• VR1: Variable Resistor (which is used to adjust RL)

• PH: Heater Consumption (typically ≤ 900 mW)

• RH: Heater Resistance (at room temperature, typically 29Ω ± 3Ω)

• △Vs: Output Voltage (difference between voltage in air and voltage in 50ppm NH3, typically ≥ 0.5V)

• α: Concentration Slope (ratio of resistance at 200ppm NH3 to resistance at 50ppm NH3, typically ≤ 0.6)

If you want to learn more about the datasheet, you must visit the link given below:

MQ137 Ammonia Gas Sensor Pinout Configuration

Till now, we’ve been discussing the pin functions of this sensor but have a look at the table below to understand the pinout configuration with a precise description:

MQ137 Ammonia Gas Sensor Packages

There are no standardized packages for the MQ137 ammonia gas sensor but it is present in more than one variety of assembly options so that it may fit in multiple types of circuits without any issue. Here are key package options widely utilized by multiple users:

MQ137 Bare Sensor Board

It is the fundamental form of the sensor which is a simpler assembly option. It consists of just the sensor and its pins for easy connection. 

MQ137 Sensor Board with Breakout Pins

It consists of the sensor board along with the additional header pins. These pins are soldered on it and provide the opportunity to connect it with the wires or the breadboard according to the convenience of the user. 

MQ137 Pre-Assembled Module

This is the most user-friendly item on the list and the following features will justify my statement:

• It includes the basic board and the additional circuitry like resistors, capacitors, and voltage regulators. 

• Some models have a pre-program microcontroller as well as an analog-to-digital converter (ADC). Such models are ready to use in the projects. Such models come in a plastic enclosure and have features like screw terminals or header pins for easy connection. 

MQ137 Ammonia Gas Sensor Alternatives

If for some reason, you want to know the alternatives that can be used in place of MQ137 then I would suggest the following sensors:

• Figaro Figaro H2S-B4 (can be adapted for NH3)

• City Technology Corporation (CTC) T8320

• Alphasense NH3-FS-400

• Gas Sensing Solutions GSS-NH3

• Mettler Toledo InPro 5000 NH3

• Teledyne API TDL-4000

Where to Buy MQ137 Ammonia Gas Sensor?

The sensors are small delicate devices and one must always choose the best platform to buy such products. Here are the most popular names in this regard:

• AliExpress

• eBay

• Amazon

MQ137 Ammonia Gas Sensor Working Principle

The study of the simple structure of this sensor aforementioned helps us to understand its working principle in just a few steps:

• As soon as the sensor is powered on, the coil of the heater circuit starts its work and the temperature of the circuit keeps increasing gradually. Usually, the pre-heating takes 20 to 30 seconds.

• Once the temperature reaches 300 Celsius, the heating temperature works only on the maintenance of the temperature instead of raising it. 

• At this temperature, the sensing element, tin oxide connected with the heating circuit through electrodes is stimulated to absorb the oxygen from the surrounding air. This reaction creates the depletion region of the oxygen ions around the sensing element. This accumulation results in an increased value of the electrical resistance. 

• The sensor works in this condition and is readily available to detect the ammonia gas. 

• Once the ammonia gas is leaked into the surroundings, the depletion region (oxygen ions) reacts with the ammonia which results in the absorption of the depletion layer. The values of the current flow are continuously indicated on the analogue pin.  

• The absorption of the depletion layer results in lower resistance. These values are indicated on the analogue pin output and show the presence of the ammonia gas. The higher values mean more concentration of the target gas in the surroundings and vice versa. 

• The digital pin is utilised to get the signal if the analogue value exceeds the threshold limit. In this way, the sensor even does not require an external microcontroller for the basic functions. 

MQ137 Ammonia Gas Sensor Physical Dimensions

There are different assembly options for the MQ137 sensor but generally, I’ve created the table that has the physical dimensions of the sensor (additional components not included):

The size may vary in different models but these are the generalized values. 

MQ137 Ammonia Gas Sensor Applications

In every place where ammonia gas is either utilized as fuel or any other process, the ammonia gas sensor is an important device. Here are some general applications where MQ137 is widely used:

• Domestic Ammonia Gas Alarm
• Air Quality Monitoring
• Industrial Ammonia Gas Leakage Alarm
• Wastewater Treatment Facilities
• Food and Beverage Industry
• Chemical Industry

Hence, today we have learned a lot about the MQ137 ammonia gas sensor. We commence the discussion with the basic introduction of the MQ137  sensor where we also saw its basic structure and components. After that, we saw the features and specifications from the datasheet of this sensor. We also read about the basic principle of working and the physical dimensions of the sensor. In the end, we saw the names of the applications where the MQ137 is used. I hope this was an informative study for you.

Hi friends! Welcome to another article in which we are highlighting the basic details of a gas sensor from the MQ sensor series. Today, our focus is on the MQ136 hydrogen sulfide gas sensor that instantly detects the presence of the sulfide gas and sends the signals through digital and analog pins to the output devices for timely indication.

Our mission is to understand the basic introduction of this sensor, so we’ll go through it and see the main points of its datasheet, such as its features and specifications. After that, we'll move towards the working principle and physical dimensions of MQ136, and consequently, there will be a discussion of the basic applications where this sensor is widely used. I am sure it is going to be a useful study for you, so let’s get started.

MQ136 Hydrogen Sulfide Gas Sensor Introduction

The MQ gas sensor series is popular for its instant detection of the target gases and their simple structure. The MQ136 is designed for the early detection of hydrogen sulfide gas even at low concentrations. We know that hydrogen sulfide is a colorless gas that has a pungent rotten egg odor and it causes multiple health issues. It is extremely dangerous and potentially, life-threatening if inhaled for a long time. Some immediate side effects of this gas are eye and nose irritation, headaches, dizziness, nausea, and vomiting therefore, it is important to detect the gas leakage at its early stage. 

The MQ136 hydrogen sulfide gas sensor is a widely used detector that has a sensing element made of tin oxide (SnO2) that absorbs the hydrogen sulfide and the change in its electrical conductance provides information about the presence and magnitude of the target gas. 

This sensor is interfaceable with different microcontrollers such as Arduino UNO, ESP32, and NodeMCU to allow communication over various mediums.

MQ136 Hydrogen sulfide Gas Sensor Basic Structure

The provided details below aim to provide insights into the fundamental components of this sensor, aiding in a better comprehension of its overall functionality and facilitating the understanding of additional information:

MQ136 Hydrogen sulfide Gas Sensor Ceramic Tube

The most basic element in the MQ136 is its ceramic tube structure. It acts as the base for the sensing element and because of its physical properties, it does not disturb the electrical resistance of the sensing element. It is present in the form of a small tube-shaped piece usually made of alumina (AL2O3) and it has excellent thermal stability.

MQ136 Hydrogen Sulfide Gas Sensor Sensing Element

The sensing element is the heart of MQ136 because the analogue values of this sensor depend on the electrical resistance of the sensing element. Here, the sensing element is a tin oxide (SnO2) which instantly reacts with gases like hydrogen sulfide gas and this is the basic way to detect its presence. It is present in the form of a thin layer on the ceramic tube and requires preheating time to be ready to react with the target gas.

MQ136 Hydrogen Sulfide Gas Sensor Heating Circuit

This sensor has a heating circuit that maintains the temperature of the sensing element at a certain level. This circuit has the following components:

• Heater Element Resistor: This resistor is integrated within the sensing element itself and its electrical resistance is responsible for generating the heat when the electrical current passes through the sensing element. 

• Series Resistor: Another resistor is connected in series with the sensing element that is mentioned as the series resistor here. The temperature control depends on the resistance value of this resistor. It performs two actions:

• Limits the current flow

• Controls the temperature of the sensing element

• Power Supply: The resistors connect the sensing element with the power supply of the circuit. This has a 5V value and it provides the necessary voltage to the sensing element. 

MQ136 Hydrogen Sulfide Gas Sensor Housing

The MQ136, just like other members of this series, has a metallic cap with ventilation holes on the sensor’s body that covers all the aforementioned components including the sensing element I’ve mentioned before. It performs two operations:

• Acts as a filter to provide the protection of the internal circuit from unwanted particles and allows only the as to pass through it

• Completes the sensor body structure and provides mechanical support

The other details of the structure depend on the type of sensor’s package and that will be discussed in detail in the next sections.

MQ136 Hydrogen sulfide Gas Sensor Datasheet

The datasheets of the product provide official and reliable information from the manufacturer that is crucial to know before using any device. Here are some important points from the datasheet of MQ136 that will help you understand the core information about this sensor:

 MQ136 Hydrogen sulfide Gas Sensor Features 

• It has a dual signal output that includes the analogue and TTL level output (digital output)

• Its TTL output signal is low if the value of the gas concentration is below the threshold value otherwise it is high. 

• It uses the LM393 IC as the main chip that acts as the comparator in the circuit and is helpful in comparing and presenting the digital and analogue values.  

• It has ESD protection. One must know that Electrostatic Discharge (ESD) is the sudden transfer of the electrical charge within the circuit that can damage it but in MQ136, the ESD protection is responsible for the health of the electrical compoeents even at high charge transfer. 

• It has diodes (such as the zener diode) for over-voltage protection so that the circuit may have a long life. 

• It has a simple structure and is easy to use.

• It is present in different packages at cheaper rates. 

MQ136 Hydrogen sulfide Gas Sensor Specification

MQ136 Hydrogen Sulfide Gas Sensor Basic Structure

Some points about the basic structure of MQ136 are aforementioned in the features but the diagram given below will justify the basic structure pictorically:

MQ136 Hydrogen sulfide Gas Sensor Temperature/Humidity Sensitivity

The performance and efficiency of the sensor may vary with some parameters such as the temperature or the humidity level in the air around it. To explain the difference, I am sharing the graph for the humidity and temperature sensitivity diagram with you. Keep in mind, that the temperature and humidity are inversely proportional to each other:

Here, 

Rs =  Resistance of the sensor in 50ppm H2S gas under different temperature and humidity levels. 

Rso = Resistance of the sensor in 50ppm H2S gas under 20℃/55%RH.

If you want to know more details about the MQ136 sensor, be sure to explore the following link:

MQ136 Hydrogen sulfide Gas Sensor Pinout Configuration

The MQ136 sulfide gas sensor comes in different packages and the pinout configuration of these packages is different. Here is the general table of pinout configuration that explains the names and roles of each pin briefly:

MQ136 Hydrogen sulfide Gas Sensor Packages

As mentioned before, the MQ136 is available in different packages and the table given below will show you the features of these packages with their names:

MQ136 Hydrogen sulfide Gas Sensor Alternatives

The MQ136 has a high sensitivity with hydrogen sulfide gas but there are some other alternatives that can be used in place of this sensor and provide the best performance. Here are some alternatives of this sensor:

• Figaro Figaro H2S-B4

• City Technology Corporation (CTC) T8310

• Alphasense H2S-FS-400

• Figaro TGS822

• Sensirion SHT11

• AMS SCS SCD30

• Gas Sensing Solutions GSS-H2S

• Mettler Toledo InPro 5000 H2S

• Teledyne API TDL-4000

Where to Buy MQ136 Hydrogen sulfide Gas Sensor

Before making a purchase decision for a sensitive device like the MQ136, it's crucial to explore various platforms and thoroughly assess both price and quality. The following platforms are recommended for acquiring the MQ136:

• AliExpress

• eBay

• Amazon

MQ136 Hydrogen sulfide Gas Sensor Working Principle

Similar to its fundamental structure, the operational principle of the MQ136 hydrogen sulfide gas sensor is straightforward. The following steps outline its working mechanism:

MQ136 Hydrogen sulfide Gas Sensor Physical Dimensions

The general dimensions of the MQ136 hydrogen sulfide gas sensor are mentioned in the table below:

MQ136 Hydrogen sulfide Gas Sensor Applications

The hydrogen sulfide gas is less commonly used for domestic use but it has the scope at industrial levels. The list below shows the names of applications in which the MQ136 is widely used:

• Domestic H2S gas alarm

• Industrial H2S gas leakage alarm

• Portable H2S gas detector

• Domestic H2S gas alarm

• Industrial H2S gas leakage alarm

• Portable H2S gas detector

• Wastewater treatment facilities

• Air quality monitoring

• Landfill gas monitoring 

I hope I’ve covered all the points in this article. I started with the basic introduction of the MQ136 and saw the details of its basic structure. I also shed light on the datasheet of this sensor and then moved towards the working principle, physical dimensions and applications of this sensor. If you are interested in learning more, you can ask in the comment section.

Hello students! I hope you are doing great. Today, I am going to share a reliable sensor that is widely used to sense the air quality in different types of projects and circuits. The increasing ratio of pollution in the air is alarming, and air quality monitoring systems are the need of the time. The MQ135 can detect and measure a wide range of gases around it and present the output in the form of digital or analogue values.

In this article, we will commence by providing a fundamental introduction to this sensor, outlining the target gases it is designed to detect. Following that, an exploration of the data sheet will be done through its essential elements, incorporating features, specifications, and other basic information. Subsequently, a detailed description of the sensor's working principle and physical dimensions will be presented to facilitate a comprehensive understanding. Finally, the article will conclude by moving towards the various applications where this sensor finds widespread usage. Let's embark on our discussion, beginning with the initial point:

MQ135 Air Quality Sensor Introduction

The MQ132 air quality sensor belongs to the MQ gas sensor series, and this does not stick to a single gas but can detect multiple gases at a time, thus contributing to detecting the overall air quality. It operates on 5V and has the feature to set the threshold value, so whenever the air pollutant crosses a certain limit, it sends the signal to its digital pin, which can be used to set the alarm. Moreover, the continuous signal of the air quality values is sent to the analogue pin.

Unlike many other sensors from the MQ series, it is sensitive to multiple gases, and these are mentioned below:

• Ammonia (NH3)

• Sulfur (S)

• Benzene (C6H6)

• CO2

• NOx

• Smoke

The list does not end here; many other harmful gases are detected with this sensor that may cause issues like lung disease, eye infections, and others, but timely detection of these gases can save lives.

MQ135 Air Quality Sensor Datasheet

A datasheet for any device holds beneficial information and is a prerequisite before choosing any device. I’ve collected some important information from the datasheet that is given below:

MQ135 Air Quality Sensor Features

• It is highly sensitive to a large number of toxic gases that are more likely to be mixed in the air. Some examples are NH3, NOx, CO2, benzene, smoke, etc., which are common air pollutants. 

• It is a small sensor, and the design is simple, therefore, it is less expensive. 

• It is a low-power sensor. 

• Some modules have a power LED that indicates the power mode.

• It is an easy-to-use sensor. 

MQ135 Air Quality Sensor Specifications

The following table will justify the general specifications of this sensor:

MQ135 Air Quality Sensor Basic Structure

As mentioned in the features, the MQ135 has a simple structure that makes it an ideal choice for different types of projects. Here is the basic circuit diagram that justifies this statement:

Here,

RH= The resistor that provides heat to the circuit. 

RL = The load resistor that is connected in series with the circuit. It limits the current flowing through the circuit. 

Vc = It is one of the voltage sources, and this label indicates the DC voltage. 

VH= it is another source voltage but this can be either AC or DC.

MQ135 Air Quality Sensor Sensitivity Curve

The MQ135 can detect multiple gases, but the sensitivity of these gases is not identical. This depends on the speed of the chemical reaction taking place with the sensing element. Based on multiple experiments, experts have designed the following sensitivity curve graph for users:

The above graph shows the sensitivity of the hydrogen, ammonia, toluene, and fresh air by keeping other parameters constant.

MQ135 Air Quality Sensor Temperature/Humidity Characteristics

The external parameters of the sensor affect its working and it shows a slightly different behaviour. Here is the diagram that shows the performance graph of the MQ135 air quality sensor at varying humidity and temperature:

The different lines show the performance of the sensor for the same gas at different humidity and temperature levels in the air.

If you want to know more details about the MQ135 sensor datasheet, you must visit the following link:

MQ135 Air Quality Sensor Pinout Configuration

Based on its structure, I’ve created the table that explains the pinout configuration of MQ135, which is given below:

The pinout may be slightly vary depending on the model of the sensor.

MQ135 Air Quality Sensor Packages

The MQ series is present in different packages for the convenience of the user. Here is a small description that shows the available packages for MQ135 and their features:

MQ135 Air Quality Sensor Alternatives

The MQ series has multiple sensors that can detect the same gases as the QM135 does, but the difference is, that the MQ135 can detect multiple gases at a time. Other members of the series can be used as an alternative to MQ135; if you want to learn about other sensor series that can be used in place of MQ135, here are some options for you:

Where to Buy ABC MQ135 Air Quality Sensor

It is important to buy sensitive devices like the MQ135 from a reliable source. For this, we have created a list of the platforms to buy the best devices, including the MQ135:

• eBay

• AliExpress

• Amazon

MQ135 Air Quality Sensor Working Principle

The simple structure of MQ135 is responsible for its ease of use and great performance. The working principle of this sensor can be understood with the help of the following steps:

MQ135 Air Quality Sensor Pre-heating

As soon as the sensor is turned on, it has to be preheated. This is done with the heating circuit of the sensor. It takes 20-30 seconds to reach a temperature of 300°C. Once this temperature is gained, it works on maintaining this temperature as long as it has the power. 

MQ135 Air Quality Sensor Sensitivity Layer

The heating mechanism stimulates the sensing element to absorb the oxygen from the air surrounding it. The sensing element is made with tin dioxide that, when it absorbs the oxygen, has a sensing layer on its surface.  This happens only for a certain limit because the accumulation of atoms on the surface creates a layer around it. This is the reason why tin oxide has a high electrical resistance in pure air. At this level, the sensing layer has limited availability of free electrons to react with the external pure air.

MQ135 Air Quality Sensor Gas Interaction

Whenever the target gas (smoke or ammonia) is present in the air, the gas molecules are absorbed by the atoms of the sensing element, and this reaction results in the absorption of this layer. As a result, the electrical conductance of the sensing element increases, and these values are indicated through the analogue data at the analogue pin. 

MQ135 Air Quality Sensor Output

The greater the target gas concentration in the surrounding area, the greater the analogue values. The whole circuit is designed in such a way that the analogue pins send the data to the output device for the indication of this change. 

Some models of the MQ135 have a digital pin that shows the presence of gas only when values reach the pre-set threshold limit. The digital pin then sends the signal to the output device. 

MQ135 Air Quality Sensor Physical Dimensions

The physical dimensions of this sensor may vary from package to package but I’ve created a table for you that generally describes it:

MQ135 Air Quality Sensor Applications

Because of its multiple gas detection capabilities, this sensor can be utilized in multiple types of projects. The general list of some important and commonly used terms is given below:

• Domestic gas leak detection

• Indoor air quality monitoring

• Industrial air quality monitoring

• Smart home appliances (air purifiers, ventilation systems)

• Portable air quality detectors

• Automotive applications (emissions, in-cabin air quality)

I hope I have covered all the points that you were searching for. I started with the basic introduction and then moved forward with the datasheet elements of this sensor. We also saw the features, specifications, and working principle in detail and in the end, we say the physical dimension and its applications in different fields of life. I hope it was helpful for you and if you ant to ask more, you can contact us in the comment section.

Hi peeps! Welcome to another tutorial where we are discussing the MQ sensor elements. Today, our focus is on the MQ131 ozone gas sensor. Ozone is a major component of air pollution and it leads to multiple health problems related to the respiratory system and other issues. It also has an adverse effect on the plants and agricultural lands. It is a pungent gas with a pale blue color and usually, it is present in very low concentrations in the normal air. The MQ131 ozone gas sensor is used in outdoor monitoring stations, industries that use ozone for experimentation, laboratories, and sensitive areas that have a high concentration of ozone gas in the environment.

In this article, we’ll study the MQ131 ozone gas sensor in detail. We’ll kick off the discussion with the introduction of this sensor. After that, we'll unveil the datasheet of this sensor where you will see the features and specifications of this product. After that, you will see the working principle and other details followed by an exploration of this product's dimensions and applications.

MQ131 Ozone Gas Sensor Introduction

The MQ131 is specially designed to detect the presence of ozone gas concentration. We know that Ozone is an allotrope of oxygen gas made with three atoms and is indicated as O3. The core component of this sensor is the tin dioxide that can react with the ozone gas therefore, with the specialized structure, it can detect the presence of this gas in the environment.

This sensor has a lower conductivity in fresh air whereas, a high conductivity when the ozone gas is present in the surrounding air. Let’s find out the basic components of this sensor:

MQ131 Ozone Gas Sensor Ceramic Tube

There is a small cylindrical shaped tube made of alumina (AL2O3) that forms the sensor base. It has excellent thermal stability and great electrical resistance. The role of this tube in the sensor is to perform two functions:

1. It provides mechanical strength to the sensing element.
2. It provides the insulating base for the other components of the perfect performance.

MQ131 Ozone Gas Sensor Sensing Layer

Unlike many other members of the MQ series that have tin oxide as the sensing element, the MQ131 ozone gas sensor has Tungsten Oxide (WO3). It is present in the form of a thin layer around the ceramic tube. This structure acts as the heart of the whole sensor because  Tungsten Oxide (WO3) is a metal oxide therefore, its conductivity lies between the conductors and insulators. The MQ131 works on the chemiresistor principle that is defined as:

"The chemiresistor principle refers to the sensing mechanism of an element in which the electrical resistance of the element changes when it absorbs a particular gas or any other material."

This will be more clear when we’ll learn the working principle of this sensor.  

MQ131 Ozone Gas Sensor Electrodes

There are measuring electrodes made of metals like gold (Au) that connect the sensing element with the ceramic tube. It creates a contact between these two and allows the current to pass through the sensing element. These are also responsible for allowing the circuit to measure the electrical resistance instantly. 

MQ131 Ozone Gas Sensor Heater Circuit

A heater circuit is required to allow the tungsten oxide to absorb the gases. This circuit consists of a coil made of nichrome wire. This coil is embedded near the sensing layer and maintains the sensor temperature at 300°C. This temperature is crucial for the reaction between gases and the sensing element. 

MQ131 Ozone Gas Sensor Housing

The whole structure mentioned before is placed and protected on a strong housing. It is enclosed in plastic or bakelite material that performs the following operations:

• It provides a strong base to the circuit so that it may act as a complete device. 

• It allows the gases to pass over it and renders the other particles or substances so that the internal structure is not disturbed. 

• It provides the connection and completes the device so it may be used in different circuits. 

Other MQ series members such as MQ-3, MQ-2, etc have a metallic mesh-like structure for the same purpose but in MQ131, most of the models have the plastic housing and only some of them have the metallic structure.

In addition to these, other elements are present in the basic structure such as the pins of the MQ131 ozone gas sensor and we’ll discuss these in detail in the datasheet. 

MQ131 Ozone Gas Sensor Datasheet

A datasheet is considered an important repository for the devices such as the MQ131 ozone gas sensor and it is always advisable to learn the datasheet before utilising any device in the circuits. Here are the important pieces of information from the MQ131 sensor. 

MQ131 Ozone Gas Sensor Features

• The MQ131 is a highly sensitive device and provides the best sensitivity to the ozone gas O3 over a large range. As a result, it detects even a low concentration of the target gas.

• It operates on very low power and, therefore, is a suitable device to be used in the Internet of Things (IoT) and other projects. 

• It is a cost-effective option for multiple types of projects.

• It shows the analogue and digital output pins where the analogue pin shows the continuous change in the gas concentration and the digital pin shows a binary signal based on pre-set threshold values. 

• It has a compact size design that makes it suitable for almost all types of circuits. 

MQ131 Ozone Gas Sensor Specifications

The following table outlines the key specifications of this high-performance ozone sensor:

MQ131 Ozone Gas Sensor’s Sensitivity Curve

To measure the performance of MQ131, a comparison between its sensitivity curve in fresh air and the one in the presence of ozone gas is useful. Here is the graph that shows both these curves:

Here,

Ro= Resistance of MQ131 sensor in the clean air

Rs= Resistance of MQ131 sensor in the air with ozone gas 

Ro/Rs= Ratio of the MQ131 sensor performance in polluted air to the clean air

MQ131 Ozone Gas Sensor’s Performance Factors

Just like other devices, the MQ131 does not perform ideally in all severe conditions. Factors like humidity and temperature affect the performance and the graph given below will explain the difference:

If you want to know more details about the datasheet then here is the link to visit:

MQ131 Ozone Gas Sensor Pinout Configuration

The MQ131 has four pins in most of its models and in some models, it has additional pins such as a heater and is not connected (NC). Here is the table that shows the description of each basic pin:

MQ131 Ozone Gas Sensor Packages

For the convenience of the user, the MQ131 sensor is present in the form of different packages. A small description of each package is given next:

MQ131 Ozone Gas Sensor Alternatives

Just like the MQ131, there are some other sensors that are created to detect the ozone gas concentration in the air. Some of these are:

• Figaro TGS series gas sensors (e.g., TGS2600, TGS2602)

• Winsen ZE08-O3 Ozone Gas Sensor Module

• SPEC Sensors O3 Ozone Gas Sensor

• Figaro TGS series gas sensors (e.g., TGS4161, TGS4161-E00)

Where to Buy MQ131 Ozone Gas Sensor

Always choose a trusted source to buy sensitive devices like MQ131. Here are the reliable options for you from where you can get different types of products and devices without any difficulty:

• eBay

• Amazon

• AliExpress

MQ131 Ozone Gas Sensor Working Principle

• The structure of this sensor is designed for uncomplicated working and effective results. Here are the steps that are involved in the working principle:

• The heater circuit heats the sensing element at the temperature of 300C and maintains it. 

• The continuous heating stimulates the sensing element to absorb the gases at a high rate. 

• When the ozone gas is present around the sensor, the surface of the sensing element absorbs the ozone molecules.

• The adsorption affects the electrical conductance of the sensing element. This change is sensed through the sensor. 

• The higher concentration of the ozone layer means a great change in the analogue values of the sensor that are indicated through the signals at the analogue pin.

• If the threshold value is set for the sensor, then on a certain limit, the digital signal at the digital pin is shown. 

• These signals are sent to the output devices for further processing.  

MQ131 Ozone Gas Sensor Logic Diagram

The MQ series features a straightforward design, and here is a diagram illustrating its internal structure:

MQ131 Ozone Gas Sensor Physical Dimensions

The MQ131 is available in multiple packages and models but usually, the general dimensions are considered so I’ve created a table with the standard size and dimensions of the MQ131 ozone gas sensor:

MQ131 Ozone Gas Sensor Applications

Ozone is not extensively present gas or is not used as a fuel therefore, it is not present in the common areas just like methane, butane, and other such gases. But, it has different kinds of applications that are used in the specialized departments. Here are some domains where the MQ131 ozone gas sensor is widely used:

• Domestic Ozone Air Purifiers:

It monitors ozone levels produced by air purifiers.

• Industrial Ozone Monitoring

 It tracks racks of ozone levels in various industrial processes here.

• Portable Ozone Detectors

It is used by personnel working in environments with potential ozone risks.

• Air Quality Monitoring

It detects ozone levels in ambient air.

• Environmental Monitoring

It monitors ozone levels in specific locations.

• Educational Experiments

It is used in educational settings to learn about gas sensing principles.

• DIY Projects

It is used in various DIY projects requiring basic ozone detection.

• Home Automation Systems

It integrates with smart home systems for automated ozone monitoring and control.

Hence in this way, we have understood the basic and fundamental concepts of the MQ131 ozone gas sensor. We commenced with the introduction of this gas sensor and then we saw some points of the datasheet such as the features, specifications, and some graphs. After that, we saw the working principle of this sensor and moved forward with the physical dimensions and application of this sensor. I hope all the things are clear to you but if you want to know more about this sensor then you can ask in the comment section.

Hi seekers! Welcome to another article discussing a sensor from the MQ gas sensor series. Today, we are discussing the MQ-9 gas sensor, which can detect gases like carbon monoxide, CH4, and LPG. It has a long life and a simple structure, and the heart of this gas sensor is the sensing element on the heating circuit. Usually, such sensors are part of large projects where they sense the target gas and send a signal for any alarming condition.

We’ll begin the discussion with the basic introduction of this sensor in which we’ll discuss the basic parts and their duties. After that, we’ll move towards the datasheet elements and study this sensor's features, specifications, and other details. You will also see its working principles and diagrams to understand the concept. In the end, there will be a glance at the applications in which the MQ-8 gas sensor plays a vital role. Let’s hover over today’s first topic:

MQ-9 Gas Sensor Introduction

The MQ-9 gas sensor belongs to the MQ series, which has multiple sensors specialised for a particular gas. In the case of the MQ-9 gas sensor, the target gases are methane, propane, and other combustible gases that may be life-threatening if leaked. As the ambient concentration of target gases rises, the sensor diligently absorbs them at a higher rate, conveying their presence through analogue values at its analogue pin.

Let's focus on the fundamental components of this sophisticated sensor, unravelling its intricacies for a comprehensive understanding:

MQ-9 Gas Sensor Sensing Substrate

A ceramic material is present on the core of the MQ-9 base. It is usually alumina (Al2O3) that is responsible for providing the mechanical strength to the sensing element. The reason to use alumina is its high thermal stability and electrical resistance so that it does not provide any interference in the sensor’s values.

MQ-9 Gas Sensor Sensing Element

The heart of this sensor is the sensing element that absorbs the target gas and senses its presence. It is a small, cylindrical-shaped structure made with tin oxide (SnO2). It is wrapped around the ceramic material in the form of a uniform layer. 

MQ-9 Gas Sensor Heater Circuit

As mentioned before, the small heating circuit is present under the sensing element. It is a coil made of nichrome wire embedded within the substrate of ceramic material. This can heat the sensing element to around 300°C. This heat starts the work of the whole sensor. 

MQ-9 Gas Sensor Electrodes

The ceramic substrate has metallic contacts on both sides that are responsible for the interface between the sensing element and the circuit. These electrodes also allow electrical current to pass through the sensing element to create a change in the electrical conductance, and this is the basic way to sense the presence of gas. 

MQ-9 Gas Sensor Datasheet

Prior to the utilization of any electrical component, it is important to peruse the datasheet that outlines the product's intricate details. Presented below are fundamental considerations essential for an informed deployment of the MQ-9 gas sensor.

MQ-9 Gas Sensor Features

• One of the unique features of the MQ-9 that makes it different from other MQ series elements is its wide range of gas detection. It is not specialised for a single gas but can detect multiple gases, which makes it a versatile sensor. The list of detectable gases for this sensor is given below:

• Methane (CH4)

• Propane (C3H8)

• Liquefied petroleum gas (LPG)

• Carbon monoxide (CO)

• It is a more versatile and cost-effective gas sensor and, therefore, is preferred in fields like industries and home safety. 

• It has a simple structure that consumes fewer resources.

• It has a fast response time that allows prompt warnings and measures. 

• It has a compact and portable design that makes it suitable for different circuits. 

MQ-9 Gas Sensor Specifications

The following table shows the basic specifications of this sensor:

MQ-9 Gas Sensor Sensitivity Character

As mentioned before, the MQ-9 can detect multiple gases, but it is important to understand that the response time and sensitivity of this sensor are different for all of these. These factors depend on the chemical reaction between the sensing element and the target gas, and here is a comparison of the performance of the MQ-9 gas sensor with different gases in the form of a graph:

MQ-9 Gas Sensor Basic Circuit

The MQ-9 gas sensor has a simple and easy-to-understand circuit. Here is the diagram that shows the test loop of this device with the help of basic labels:

Here, 

VH = Heater voltage

Vc = Test voltage

VRL = Voltage on load resistance

RL = Load resistance

If you want to know more about the datasheet or want to study it in detail, then you can visit the following link:

MQ-9 Gas Sensor Pinout Configuration

The MQ-9 gas sensor has four pins. The description and details of each of them are mentioned below:

MQ-9 Gas Sensor Alternatives

Here is a list of the alternative options that can be used in place of MQ-9. The performance of these sensors is not identical to that of the MQ-9 but experts may use them in some projects:

• Figaro TGS series

• Sensirion SGP series

• Amphenol SGX series

• GasSense IR series

• PerkinElmer NDIR-1 series

Where to Buy MQ-9 Gas Sensor 

The electrical components, such as MQ-9 have a sensitive structure; therefore, always choose the best product from the best platforms for quality results. The following are some popular choices for such elements:

• eBay

• AliExpress

• Amazon

MQ-9 Gas Sensor Working Principle

The working principle of this sensor is similar to that of other MQ series sensors. It works on the chemiresistor working principle, which means the change in the electrical resistance of the sensing element results in the output values of this sensor. Here are the steps that will explain the previous statement:

MQ-9 Gas Sensor Substrate Heating

As soon as the sensor is powered on, the heating circuit starts increasing the substrate (alumina) temperature. The internal coil of the substrate heats it, and this change is uniformly distributed to the cylindrical shapes sensing element. 

MQ-9 Gas Sensor Depletion Region

The heated substrate maintains a temperature of 300 °C, and it stimulates the tin oxide to absorb the oxygen from the surroundings. Soon, the hydrogen ions start accumulating on its surface, and as a result, a depletion region is formed around the sensing element that increases the electrical conductivity of tin oxide. 

MQ-9 Gas Sensor Gas Absorption

The depletion region remains on the surface of tin oxide in the air until there is no target gas mixed in it. If any of the target gases are leaked into the air, they start reacting with the depletion region around the sensing element. This reaction results in the absorption of the depletion region. As a result, the electrical conductivity of the tin oxide increases as the sensor indicates this change in resistance through the analogue pin. In other words, the values of the electrical resistance are always present on the analogue pin, but sudden changes in the resistance are alarming on the analogue pin. The higher the target gas concentration, the more sudden and large changes are seen on the analogue pin.

MQ-9 Gas Sensor Gas Digital Value

The digital values show the presence or absence of the target gas without indicating its concentration. The digital pin shows only two outputs as mentioned in the pin description.

The signals from the digital and analogue pins are sent to the output device that indicates the results. 

MQ-9 Gas Sensor Physical Dimensions

The MQ-9 gas sensor does not have multiple packages. The size and dimension may vary from model to model, but usually, it is a compact product that can be used in different types of circuits. Here is the table that shows the general package dimensions of this sensor:

MQ-9 Gas Sensor Applications

The MQ-9 gas sensor finds extensive application in various projects, catering to significant domains. Below are key sectors where its utilization proves pivotal:

• Home Safety

• Industrial monitoring

• Environmental monitoring

• Portable gas detectors

• DIY projects (Air quality monitoring systems, smart home gas leak alarms, educational experiments)

Today, we have seen detailed information about the MQ-9 gas sensor. It is a versatile sensor that provides the sensing of multiple gases at a time. We commenced our exploration with a comprehensive introduction to the MQ-9 gas sensor. Progressing further, we moved towards the datasheet, unravelling its distinctive features and specifications. An in-depth exploration of the sensor's operational principles ensued. Finally, we comprehended its physical dimensions and explored the diverse spectrum of applications it caters to. I hope it was an informative article for you, and if you want to know more, you can contact us. 

Hey fellow! Welcome to the next article on the MQ series of sensors, and today our focus is on the MQ-8 which is used to sense the presence of hydrogen gas. We know that hydrogen is a colorless, odorless, and tasteless gas that humans can not sense easily. It is not toxic like carbon monoxide and other such examples but still, the excess presence of this gas can be life-threatening because it is highly flammable. The air is a mixture of different gases and hydrogen gas when combined with some specific gases, can be harmful to life. In the presence of a bare flame or other ignition material, hydrogen can start the ignition, and here, the duty of sensors like MQ-8 starts. We’ll examine the basic information about this sensor in detail.

In this article, we’ll start reading about the basic introduction to the MQ-7 hydrogen gas sensor. We’ll see the basic data sheet, specifications, features, and core information about this product. After that, we’ll move on to this work in detail and understand its structure to analyze its output. We’ll end this chapter with the physical dimensions and the applications of this sensor in different domains of life. There are many things to learn here so let’s move towards the first topic:

MQ-8 Hydrogen Gas Sensor Introduction

The MQ-8 is a specialized sensor mainly designed to sense the surplus amount of hydrogen gas that can be harmful to people with sensitive lungs because excess inhalation of hydrogen can displace the oxygen atoms in the lungs. Moreover, it may be inflammable in the factories or industries using the particular material.

For some materials, the hydrogen gas can be the cause of brittleness and even cracks therefore, is a harmful gas for materials like storage tanks and pipelines. In such areas, the sensors like MQ-8 are used to detect the presence of any hydrogen gas leakage. The structure is designed in such a way that as soon as the surplus amount of hydrogen is sensed in the environment, it sends the signal through the analog and digital pins to the output devices for indication.

Here are the basic parts of the MQ-8 hydrogen sensor:

MQ-8 Hydrogen Gas Sensor Sensing Element

The heart of this sensor is the sensing element that lies on the base of a circuit that continuously heats it. This element is made of ceramic material that has a layer of tin dioxide (SnO2) on it. This layer is responsible for absorbing the high concentration of hydrogen gas in the surroundings as a result, the sensor can indicate its presence. 

MQ-8 Hydrogen Gas Sensor Heater

A heater circuit is present in the core of this sensor which is a heater coil that is wrapped around the sensing element and continuously heat it. This circuit is always on and this constant heating is crucial for the accuracy of the sensor performance. 

MQ-8 Hydrogen Gas Sensor Electrodes

Two electrodes are connected to the sensing element that is responsible for working according to changes in the circuit resistance. This resistance depends on the ion formation reaction on the sensitive element. 

MQ-8 Hydrogen Gas Sensor Filter

A stainless steel mesh network is present on the whole circuit that consists of two layers. These layers are responsible for the following tasks:

1. Protection of the internal element from the outward unwanted particles. It simply allows the gases to pass through it to filter the articles. 

2. Helps the internal structure to retain its position. 

Moreover, it has pins, voltage regulators, filtering capacitors, and pre-heat resistors that support the smooth performance of the MQ-8 hydrogen gas filter.

MQ-8 Hydrogen Gas Sensor Datasheet

Let us discuss some important parts of the datasheet that will help you understand the product details. We’ll are making a start with its features:

MQ-8 Hydrogen Gas Features

• It is a sensitive detector and its range is between 100 to 10,000 PPM where the PP means the parts per million. 

• It can sense the small leakage of hydrogen gas and, therefore, is considered a reliable sensor. 

• The structure is designed in such a way that it detects the hydrogen gas accurately even in the presence of other gases such as methane, ethanol, and carbon monoxide. As a result, the sensor does not provide the false alarms. 

• This sensor shows a fast response time that ranges between 30 seconds to 100 seconds after it is powered on. 

• It has a simple and small circuit that does not consume a lot of energy. Moreover, the easy circuit makes it less costly.

• Another advantage of a simple circuit is its long life. Moreover, it is a lightweight device. 

MQ-8 Hydrogen Gas Sensor Specifications

Here is a table of the specifications for the MQ-8 hydrogen gas sensor:

MQ-8 Hydrogen Gas Sensor Internal Structure

The internal structure of this sensor is simple as discussed before in the previous section. Here is the diagram that will explain the internal circuit and its basic labeling:

This diagram will be understood by using the detail of each label as mentioned below:

1.  Gas Sensing Layer (SnO2):

• SnO2 material used for gas sensing.

2.  Electrode (Au):

• Electrode made of gold (Au).

3.  Electrode Line (Pt):

• Electrode line composed of platinum (Pt).

4.  Heater Coil (Ni-Cr Alloy):

• Heater coil material: Nickel-chromium alloy (Ni-Cr).

5.  Tubular Ceramic (Al2O3):

• Tubular ceramic material: Aluminum Oxide (Al2O3).

6.  Anti-explosion Network:

• Stainless steel gauze (SUS316 100-mesh) is used as an anti-explosion network.

7.  Clamp Ring (Copper Plating Ni):

• Clamp ring made of copper with nickel plating.

8.  Resin Base (Bakelite):

• Resin base material: Bakelite.

9.  Tube Pin (Copper Plating Ni):

• Tube pin made of copper with nickel plating.

If you want to know more about the datasheet then you can visit the link given below:

MQ-8 Hydrogen Gas Sensor Pinout Configuration

As with all members of the MQ series, the MQ-8 hydrogen gas sensor has four pins and in some models, an additional pin is also present. Here is the table that shows the pin number, its name, and a brief description:

MQ-8 Hydrogen Gas Sensor Packages

For the convenience of the user, manufacturers present different types of packages for the MQ sensors. Here is the table that explains the SMD and DIP package of the MQ-8 hydrogen gas sensor:

Where to Buy MQ-8 Hydrogen Gas Sensor?

there are multiple options to buy such products online but the most trusted ones are listed below:

• eBay

• AliExpress

• Amazon

MQ-8 Hydrogen Gas Sensor Working Principle

If you've followed the details about the sensor's structure in the previous section, understanding how the MQ-8 hydrogen sensor works should be straightforward. Here are the steps that show the working principle in this regard:

• As soon as the sensor is powered on, the heating circuit starts its duty. In 20 to 100 seconds, it starts heating the sensing element. 

• The heating process stimulates the tin oxide to absorb the oxygen gas from the surroundings. This created a depletion region consisting of hydrogen ions around the tubular-shaped tin oxide.

• Soon, the depletion region is strong enough to enhance the resistance of the circuit. At this point, the MQ-8 hydrogen sensor is ready to sense the pure hydrogen gas in the environment. 

• In the case when there is a leakage of the hydrogen gas, the sensing element starts reacting with it. 

• If there is a notable amount of hydrogen in the environment, the depletion region around the sensing element starts resting with it. As a result, the resistance of the circuit starts decreasing. 

• The values of the electrical current passing through the circuit increase and eventually, the analogue values are sent to the output device through the analogue pin. 

• By the same token, the digital pin is stimulated when a particular analogue value is crossed. 

• These signals are then sent to the output device. Usually, the projects are made using any microcontroller or other such devices.  

MQ-8 Hydrogen Gas Sensor Physical Dimensions

The physical dimensions of such products vary from model to model. I‘ve created a general table that shows the dimensions of the MQ-8 hydrogen gas sensor mentioned here:

MQ-8 Hydrogen Gas Sensor Applications

Hydrogen gas is not toxic and it is less commonly used as compared to the other gases therefore, it is not widely used in household applications but it is used in the areas where large amount of hydrogen is used. Here is the list of examples of some applications:

• Industrial hydrogen gas monitoring

• Hydrogen gas leakage detection

• Fuel cell applications

• Hydrogen-powered vehicle safety

• Chemical processing environments

• Laboratory gas detection

• Hydrogen storage facilities

• Aerospace industry applications

• Hydrogen fuel production and storage

• Energy-related processes

Today, we learned a lot about the MQ-8 hydrogen gas sensor. We initiated the discussion through the introduction of this sensor where we discussed its basic parts. Following that, we moved into the datasheet, uncovering a trove of information encompassing features, specifications, and the sensor's internal architecture. Progressing further, we unveiled the intricacies of its working principle, concluding our exploration with a glimpse into the diverse applications harnessing the potential of this sensor. If you crave more knowledge, stick around for our forthcoming insights.

Hello peeps! I hope you are having a good day. We all know carbon monoxide is a dangerous and harmful gas that can even be fatal. It is a colorless and odorless gas so it is difficult to sense its presence therefore, different types of sensors and indicators are required to make the places safe especially those where there is a chance for carbon monoxide gas production as a byproduct. Here, one of the most promising detectors is the MQ-7 carbon monoxide sensor which instantly detects and indicates the presence so the users may save their lives. This is the most popular choice for this purpose because of its low cost, high performance, and instant response. 

This article will commence by introducing the MQ-7 carbon monoxide sensor. Subsequently, we will delve into essential details from its datasheet, exploring its structure, pinout configuration, and performance-related graphs. Additionally, we will examine alternatives and package details, providing a comprehensive understanding. A detailed exploration of the working principle will follow. Towards the conclusion, notable examples highlighting the significant role of this sensor will be discussed. Let's embark on the exploration of the initial topic:

MQ-7 Carbon Monoxide Gas Sensor Introduction

The sensitive material of the MQ-7 carbon monoxide gas sensor is tin dioxide (SnO2). This is a reactive material to carbon monoxide and the basic working of this sensor depends on the heating process of this sensing element. Carbon monoxide (CO) is not usually present in fresh air therefore, the sensor does not provide any signal until it senses any leakage or danger.

This sensor consists of the following parts:

MQ-7 Carbon Monoxide Gas Sensor’s Gas Sensitive Layer

Just like other MQ sensors, this one also has a sensitive element made of ceramic that has a layer outside it. This layer consists of tin dioxide (SnO2) and has the feature of absorbing the target gas. In the case of MQ7, the tin dioxide absorbs the carbon monoxide and indicates its presence as soon as it comes in contact.

MQ-7 Carbon Monoxide Gas Sensor’s Gas Electrodes

The MQ-7 has electrodes that facilitate electrical contact with the sensitive material. Usually, it is made with the gold for the best performance. These allow the measurement of the electrical resistance.

MQ-7 Carbon Monoxide Gas Sensor’s Heater Coil

There is a coil in the heart of this sensor. This is made of alloy like Ni-Cr and provides heat to the sensitive layer to enhance its reaction and sensitivity.

MQ-7 Carbon Monoxide Gas Sensor’s Tubular Ceramics

The censor has a tubular structure of ceramic material such as alumina (Al2O3) and it provides support and strength to other components so that they may be at their place.

MQ-7 Carbon Monoxide Gas Sensor’s Anti-explosion Network

There is a network of double stainless steel mesh that performs two functions:

1. It allows the gases to pass through it and retains the presence of any unwanted particles outside the network.
2. It protects the internal structure because that is very reactive and delicate therefore, with the help of this network, all the internal structure remains in its place.

MQ-7 Carbon Monoxide Gas Sensor’s Resin Base

To create the whole system of the gas sensor, there is a firm base made with bakelite or other materials that provide the strength and the pin structure that ensure the working of the whole sensor.

Moreover, there are tube pins and clamp rings that provide extra strength to the circuit of the MQ-7 monoxide gas sensor. 

MQ-7 Carbon Monoxide Sensor Datasheet

Before using any electrical component, it is important to understand the technical specifications. Here are some points to know before using the MQ-7 carbon monoxide sensor:

MQ-7 Carbon Monoxide Sensor Features

• This sensor has an analog pin that shows the presence of carbon monoxide through the analog values

• The digital pin is responsible for showing the presence or absence of the gas through a single value. 

• It has a simple structure therefore, it is a less power-consuming component. 

• It has a long life and is considered ideal to use in circuit-like IoT projects.

• It is continuously in power so whenever it senses carbon monoxide in its surroundings, it shows a rapid response. 

• The typical detection range of this sensor is 10 ppm to 1000 ppm but it may vary depending on the model. 

MQ-7 Carbon Monoxide Sensor Specification

MQ-7 Carbon Monoxide Sensor Pinout Configuration

Just like structure and other features, the pinout configuration of the MQ-7 carbon monoxide sensor has four pins and a simple structure. Here is the table that shows the pin number, names, and a brief description:

The details of each pin will be clear when we study the working of this sensor in the communing section.

MQ-7 Carbon Monoxide Sensor Packages

For the convenience of the users, the MQ-7 carbon monoxide is available in different packages. Here is the detail of the most common packages:

MQ-7 Carbon Monoxide Sensor Through-Hole Package (DIP)

• This is the most common package that usually has four pins for connection to a PCB through the soldering process.

• It's readily available for use and the advantage is, that it has easy integration into existing circuits.

• The negative point is, that it requires manual soldering and has a larger footprint compared to other packages.

MQ-7 Carbon Monoxide Sensor Surface Mount Package (SMD)

• This package is relatively smaller and is designed for surface mounting on PCBs.

• It offers easier integration into printed circuit boards and therefore is used by beginners as well. 

• The negative point is, that it requires specialised soldering equipment that is not always available for all the users and may be more sensitive to environmental factors.

MQ-7 Carbon Monoxide Sensor Module Package

• It includes the sensor itself along with additional components for better working such as the voltage regulators and filtering capacitors.

• It's easier to use as compared to the other options in the list and provides plug-and-play functionality.

• The negative point is, that it has a larger footprint and can be more expensive compared to basic packages.

MQ-7 Carbon Monoxide Sensor Alternatives

Some other fellows of the MQ family also can detect carbon monoxide to some extent but it is advisable to use the most sensitive and particular devices to detect such types of toxic gases. Here are noteworthy alternatives that can substitute for the MQ-7 carbon monoxide gas sensor:

• MQ-9 is another sensor from the MQ series and it can detect multiple gases including carbon monoxide and methane. 

• MiCS-5524 is the sensor that can detect gases like Carbon Monoxide, Methane, and LPG Gas Sensor. It's a small sensor and is used in multiple projects in different domains. 

• An important alternative for this sensor is the Figaro TGS Series that have multiple gas sensors for gas detection. 

• The SGX Sensortech MICS-5524 is another sensor that can detect carbon monoxide, methane, and LPG gas and shows high sensitivity towards multiple gases. 

Where to Buy MQ-7 Carbon Monoxide Sensor

Buying the electrical component is a big responsibility because every member of the circuit affects the overall accuracy. You must buy sensors like MQ-7 without facing technical issues:

• eBay

• AliExpress

• Amazon

MQ-7 Carbon Monoxide Sensor Working Principle

• The basic working principle of this sensor is similar to the other MQ series compoeents. In the heart of this sensor, the tin oxide (SnO2) is present in a tubular shape. The circuit of this sensor is designed in such a way that as soon as the circuit is powered on, the tin oxide is heated to stimulate its absorption process at a high rate. 

• Once the tin oxide is stimulated, it absorbs the oxygen from its surroundings and the ions are created at a high rate. As a result, a depletion region forms around the sensing element that enhances the electrical resistance. 

• Now, the electric current passing through the sensor is very small and this indicates that there is no toxic carbon monoxide present in the surroundings. 

• As soon as there is an amount of CO in the air and it reaches the sensor, the depletion region starts reacting with it and as a result, the smaller number of ions contributes to less resistance. 

• In the end, the low resistance results in the high electrical conductance that is indicated in the sensor. 

• The output on the analog pin is directly proportional to the amount of carbon monoxide present in the air. 

• MQ-7 has a potentiometer in it through which the threshold values are set. Once the analogue values reach the threshold value, the sensor shows the signal through the digital pin. A comparator is used in the module that is responsible for comparing the values on these pins. 

• These pins are connected to the output devices which may be any buzzer, screen, or anything else based on the project. 

MQ-7 Carbon Monoxide Sensor Physical Dimensions

Before using MQ-7 in the circuit, the physical dimensions will help you to understand its size and other specifications. This table will show the details of each parameter with the unit:

MQ-7 Carbon Monoxide Sensor Applications

Carbon monoxide is used in different industries in such places, so using the sensing system is a must. Here are some general examples where the MQ-7 carbon monoxide can be integrated for the detection:

• Air quality monitoring

• Industrial safety

• Home and office safety systems

• Environmental monitoring

• Combustible gas detection

• Automotive emissions monitoring

• Gas leak detection systems

• Portable gas detectors

• Agricultural and greenhouse applications

• HVAC systems

Hence, today we have read the details of a life-saving sensor that is MQ-7 carbon monoxide sensor. It is used in multiple projects and we started learning through its introductions and details of its internal components. After that, we saw the datasheet elements like its specifications, features, and some important information about its structure. just after that, we read about its working principle, physical dimensions and some important applications where this sensor can be used. I hope all the points are clear to you but if you want in-depth information then you can ask in the comment section.