The CO2 sensor (carbon dioxide sensor) is an electronic device that can measure the concentration of carbon dioxide gas present in the air. It is measured using the unit ppm (parts per million) and has a presence of around 400 ppm. Co2 sensors can provide data regarding air quality that helps in optimizing the CO2 gas present in the air to improve energy efficiency.

In this glossary, Infineon discusses an overview of Co2 sensors:

  • Where is the Co2 sensor used?
  • Benefits of Co2 sensor
  • Applications of Co2 sensors
  • How do Co2 sensors work?
  • Infineon’s CO2 sensor product portfolio

Carbon dioxide is a colorless and odorless gas that is created through various means both natural and manmade such as combustion, respiration, and decomposition. Carbon dioxide has been identified as one of the major greenhouse gases that affect the atmosphere.

Measuring Carbon dioxide gas is important in monitoring the combustion process, measuring eco-efficient indoor air quality, and monitoring and managing various respiratory conditions in the lungs.

Where is the CO2 sensor used?

Co2 sensors are used in many industries such as pharmaceuticals, agri-food, beverage, refrigeration, and brewing. Carbon dioxide sensors help in detecting the CO2 gas content in the surroundings. Once it detects the carbon dioxide gas content, it generates an alarm to take necessary action.

Two of the most prominent use cases of carbon dioxide sensors are:
  1. In industrial settings, CO2 sensors can be used to monitor emissions from factories and power plants.
  2. In the automotive industry, they can be used to help optimize engine performance and reduce emissions. 

Carbon dioxide sensors are an important tool for monitoring greenhouse gas emissions, environmental compliance, energy efficiency, agriculture practices, climate change research, waste management, real-time monitoring, and overall contributing to the global efforts to combat climate change and transition to a more sustainable future.

Benefits of CO2 sensors

Co2 sensors play an important role in making favorable atmospheric conditions. They help maintain good indoor air quality, reduce energy costs, optimize engine performance, monitor emissions from factories and power plants, identify sources of carbon emissions, and promote more sustainable practices. They are becoming more affordable and available, can be used in various industries, and can even monitor the effectiveness of carbon capture and storage technologies. In general, Carbon dioxide sensors can help reduce the impact of human activities on the environment.

How do CO2 Sensors Work?

Co2 sensor technology has become increasingly popular in recent years for its ability to measure the amount of Co2 (carbon dioxide) present within a certain environment. The device generates an infrared light beam tuned to a specific wavelength that is absorbed readily through Co2 molecules. For Carbon dioxide gas the wavelength typically used is 4.26um. The Carbon dioxide sensor working principle is similar to infrared hydrocarbon detectors, but the difference is the selection of IR wavelength & filter.

Types of Co2 sensor

There are different types of CO2 sensors, but here's a general overview of how they work:

NDIR sensors

These sensors measure the absorption of infrared light by carbon dioxide molecules in the air. A light source emits infrared light through a sample chamber containing the air to be tested. The light then passes through a filter that only allows wavelengths that are absorbed by CO2 to pass through. A detector on the other side of the sample chamber measures the amount of light that makes it through the filter, which is directly proportional to the amount of CO2 in the air.

PAS sensors

These sensors measure the absorption of modulated light by CO2 molecules in the air. A modulated light source emits light through a sample chamber containing the air to be tested. The modulated light is absorbed by the carbon dioxide molecules in the air, causing the air to heat up and produce acoustic waves. A microphone on the other side of the sample chamber picks up these acoustic waves and converts them into an electrical signal, which is then measured and used to determine the concentration of CO2 in the air.

EC (Electrochemical)sensors

These sensors measure the electrical current produced when CO2 reacts with an electrolyte. The sensor contains an electrode coated with an electrolyte that reacts with CO2. When CO2 comes into contact with the electrode, it produces an electrical current that is proportional to the concentration of CO2 in the air.

Metal Oxide Semiconductor (MOS) Sensors:

These sensors measure changes in the electrical conductivity. When MOS sensors detect the interaction between carbon dioxide gas and the metal oxide surface. These sensors offer cost-effective solutions for applications such as indoor air quality assessment and automotive monitoring.

Infrared gas sensor

These sensors measure the absorptions of IR (Infrared)radiation by carbon dioxide. The IR gas sensor primarily consists of an infrared source, a detector, and a gas chamber. The change in the infrared light (transmitted or reflected) due to Co2 absorption, determines the carbon dioxide gas concentration within the certain environment.

There are various types of CO2 sensors that provide different requirements in terms of accuracy, power consumption, environmental conditions, and response time. Selecting a certain Co2 sensor depends on the specific operating environment and product or application need.

Applications of CO2 sensors

Carbon dioxide sensors create effortless ways to identify when carbon dioxide gas levels are increasing which in turn protects the performance of certain environments. The diverse types of Co2 sensors cater to various applications, providing valuable tools for environmental monitoring, medical diagnostics, industrial safety, and research.

Some of the applications where Carbon dioxide sensors are majorly used are:
  • Safety Industries.
  • HVAC/ Indoor Air Quality Industries to monitor air quality.
  • Life-Science & Medical Industries.
  • Aerospace Industries.
  • Transportation Industries.
  • Industrial Applications.
  • Research Applications.
  • Agriculture Industries.
  • Mining.
  • Gasification.
  • Indoor air quality.
  • Process Control.

Infineon’s CO2 sensor product portfolio

Infineon develops CO2 sensors using superior MEMS (microelectromechanical systems) technology. The XENSIV™ PAS CO2 sensor integrates a PAS transducer, a microcontroller, and a MOSFET on the PCB to provide accurate, real-time CO2 measurement. Infineon's CO2 sensor delivers superior accuracy, providing a direct readout of the real CO2 level, not simply a correlation. 

The sensor matches the performance of NDIR and EC CO2 sensors, while being more affordable and compact, making it the ideal solution for smart home and building automation applications. The reliable CO2 sensor measurement enables smart CO2 measurement and monitoring of indoor air quality, allowing users to take control of their environmental conditions and experience improvements in health, productivity, and overall well-being.