Carbon dioxide gas, often known as CO2 gas, is a colorless, odorless gas that is produced by a variety of activities, including organic decomposition, combustion, and respiration. So, monitoring CO2 gas is important for the functioning of the lungs during medical procedures, ecological CO2 gas emission levels in indoor air quality, and combustion processes. However, The nondispersive infrared (NDIR) method can monitor carbon dioxide gas more accurately than electrochemical technology. Numerous industries, including the pharmaceutical, agri-food, beverage, refrigeration, and brewing sectors, use CO2 sensors for monitoring CO2 gas. Anyway, an overview of carbon dioxide sensors, or CO2 sensors, and how they function with applications is covered in this article.
What is a Carbon Dioxide Sensor?
The term "carbon dioxide sensor" refers to a device that measures the amount of CO2 gas present in the air or its surroundings. The device sounds an alarm as soon as it detects the presence of CO2 gas so that people can respond immediately. This kind of sensor is essential for establishing a favorable atmosphere for people in the general population.
CO2 detector working principle. (how do CO2 sensors work?)
The operation of CO2 sensors is similar to that of infrared hydrocarbon detectors. They produce a beam of infrared light that has been precisely tuned so that it to be readily absorbed by CO2 molecules. The selection of IR wavelength and filter is the main difference between an IR hydrocarbon detector and a CO2 sensor. Since some of the infrared light is absorbed by each CO2 molecule, the amount of absorption is proportionate to the percentage of CO2 present in the surrounding air. These CO2 sensors use sapphire windows to protect the infrared transmitter and receiver components from any acidic gasses found in the surrounding air.
Types of CO2 sensor
CO2 sensors come in various types, including non-dispersive, electrochemical, semiconductor, and catalytic combustion.
NDIR CO2 Sensor
The name "NDIR" refers to Non-dispersive Infrared, which employs certain light wavelengths to measure the amount of CO2 in the air. Every element on Earth simply absorbs a certain type of light. When air reaches the gas sensor, it creates a set of lights at one of the specific CO2 wavelengths, typically around 4 microns at one end of the sensor. The other face will have a container that will calculate how much light makes it to the opposite face. When the light is turned on, CO2 in the air absorbs the beams. So, the sum of light that makes it to the other face of the CO2 sensor reduces. The amount of light absorbed is mostly determined by the amount of CO2 available. higher CO2 means higher light absorption.
The NDIR CO2 sensor has several advantages, including fast analysis speed, high sensitivity, a long service life, and excellent stability. The NDIR CO2 sensor has several shortcomings, including high power consumption, a complex structure, and high cost.
Catalytic Combustion CO2 Sensor
These kinds of CO2 sensors come with a catalyst-like basic element that uses the catalyst coating on the face of a certain type of resistor. The combustible gas at a specific temperature is burned catalytically on the surface, as in the carbon dioxide sensor principle. This CO2 sensor is also known as a thermal combustion sensor. These sensors have been enhanced and are now widely utilized in a variety of industries, as trustworthy sensors.
The advantages of a catalytic combustion CO2 sensor include fast response, exact measurement, and quick response. The limited gas range of catalytic combustion CO2 sensors is one of its drawbacks.
Electrochemical CO2 Sensor
This is a sort of chemical sensor that converts the concentration of carbon dioxide gas into an electrical signal during an electrochemical reaction. Electrochemical categories are classified according to electrical signal detection, such as current, capacitive, and potential. When CO2 gas enters the sensor, it reacts chemically to the sensor. Hence, the CO2 sensor goes through an electrical charge. So, depending on the type of sensor, the reaction can cause the CO2 sensor to receive an electrical current, modify the existing current, or change how well the sensor will carry a current. Following that, the sensor will calculate how much gas has been used depending on the change.
Electrochemical CO2 sensors provide several advantages, including low cost, simplicity of operation, and quick measurement speeds.
The main disadvantages of electrochemical CO2 sensors are that precision can be lost, they are easy to drift, have a short life, are prone to aging, and precise measurement is easily affected by other gases.
Semiconductor CO2 Sensor
This sensor can be created using the oxidation-reduction reaction of the gas on the surface of the semiconductor to change the resistance value of the sensitive element. Once the semiconductor device is heated to a certain temperature, it absorbs gas molecules that come into contact with its surface. As a result, these molecules are absorbed, freely dispersed over semiconductor surfaces, and lose their energy of movement. Some gas molecules will vanish, while the remaining molecules will be thermally wiped out and absorbed by the semiconductor surface. When the semiconductor work function is low in comparison to the absorbed molecules, these molecules take electrons from the semiconductor device, and the semiconductor device surface forms a charge layer. If the semiconductor work function is greater than the absorbed energy molecules, the molecules will discharge electrons into the device, resulting in positive ion absorption.
The advantages of semiconductor CO2 sensors include their stable structure, short reaction time, and high environmental resistance. The disadvantages of a semiconductor CO2 sensor include: it is only impacted by temperature, the reading will be influenced by other compounds in the air, and so on.
CO2 Sensors applications.
- Safety Industries.
- Indoor air quality.
- HVAC
- Life science & Medical industries.
- Mining
- Biogas.
