[Editor's Note] Indoor air quality affects the health of residents. Indoor air quality can be contaminated with carbon dioxide, fine dust, mold, bacteria, etc., which can cause various diseases. In the pandemic era, as the time spent indoors increases, managing indoor air becomes more important, and the demand for _CO2 sensors capable of accurate measurement is also increasing. In the midst of this, we met with Kim Seong-tae, Manager of Infineon Korea, a global semiconductor solution company, to hear about the operating principles of the new CO ₂ sensor and the features of Infineon's XENSIV™ PAS CO ₂ sensor.

■ What is the background to the _CO2 sensor becoming an issue?

Modern people spend most of their time indoors, in cars, trains, airplanes, and buildings.

Carbon dioxide concentration in indoor environments directly affects human health and work performance.

The _CO2 sensor measures the concentration of carbon dioxide, which can be an important indicator of indoor air quality, helping maintain a comfortable and healthy indoor space.

_CO2 sensors have a wide range of applications, including: △Preventing headaches, drowsiness, and decreased concentration caused by high carbon dioxide concentrations; △Smart buildings that detect _CO2 concentrations and save energy through proper ventilation during heating and cooling; △Smart farms that optimize plant growth in greenhouses and houses; and △Checking the concentration of viruses that spread through the air, such as the COVID-19 virus.

■ What types of _CO2 sensors are there?

Popular rooms to choose fromThere are three methods: the non-dispersive infrared (NDIR) method, the electrochemical method (EC), and the _eCO2 method, which estimates carbon dioxide concentration using an algorithm.

■ Please explain the pros and cons of the _CO2 sensor method above.

NDIR sensors utilize the characteristic of _CO2 absorbing IR in a specific band.

Due to its operating principle and structure, it is relatively large and expensive.

Among the currently commercialized technologies, PAS can measure _CO2 most accurately, but its large size and high price make it unsuitable for small IoT devices or smart home devices.

Electrochemical sensors are relatively smaller and less expensive than NDIR sensors.

However, it is difficult to apply to applications that require accurate carbon dioxide concentration or applications that use batteries because of its low accuracy and high current consumption.

The eCO ₂ sensor is the smallest of the three and can be implemented at the lowest price.

However, since it is a method of estimating the corresponding _CO2 value based on an algorithm rather than directly measuring _CO2 , the accuracy is low because it is calculated using several assumptions, and real-time measurement is difficult because it is calculated using existing trends.

■ Please introduce an application using the Infineon _CO2 sensor.

_CO2 is one of the main indicators of indoor air quality.<br />
It is applied to HVAC (Heating, Ventilation, Air Conditioning) systems such as air conditioners and air conditioners to maintain comfortable indoor air, as well as air purifiers.

Monitor indoor air quality and ventilate appropriately when _CO2 concentration is high to optimize heating, cooling, and air purification efficiency and keep indoor air quality healthy and comfortable.

■ What are the special features of Infineon’s XENSIV™ PAS CO ₂ sensor?

The Infineon XENSIV™ PAS CO ₂ sensor was developed using Photoacoustic Spectroscopy, leveraging Infineon’s accumulated expertise in MEMS technology, to overcome the shortcomings of existing sensors.

Photoacoustic spectroscopy (PAS) is a method of using the energy absorbed by a substance when the substance absorbs light of a certain frequency to detect sound.

Gas molecules in the air absorb infrared light of specific wavelengths, and carbon dioxide absorbs infrared light of 4.2 μm wavelength.

This absorbed infrared radiation is converted into vibrations of molecules in the air.

The PAS sensor measures the vibration of converted molecules using an acoustic detector to calculate the concentration of carbon dioxide in the air.

Infineon's XENSIV™ PAS CO ₂ sensor delivers comparable or better performance compared to conventional NDIR sensors, but in a smaller size and at a lower price.

Key features of the Infineon XENSIV™ PAS CO ₂ sensor are △14mm x 13.8mm x △ Small size of 7.5mm △ Built-in IR transmitter and IR filter △ Built-in microphone type sound detector △ Microcontroller for onboard signal processing △ Sophisticated algorithm △ Built-in MOSFET to drive infrared light source, etc.

Additionally, the chamber can be acoustically isolated from external noise to minimize the effects of noise.

The built-in microcontroller calculates and updates the concentration of carbon dioxide in ppm, and uses advanced compensation and configuration algorithms to provide accurate _CO2 sensing in a variety of environments.

■ Please explain an example of using the Infineon XENSIV™ PAS CO ₂ sensor.

Infineon's XENSIV™ PAS CO ₂ sensor is being applied and reviewed in various home devices at home and abroad.

It is applied to various smart IoT devices such as air purifiers and air conditioners that require indoor air quality measurement.

It is applied to smart buildings to enable ventilation according to the concentration of carbon dioxide.

It is also being considered for application to smart farms to optimize crop production.

■ Lastly, please say a word to your readers.

For modern people who spend a lot of time indoors, carbon dioxide measurement provides the best conditions and has many advantages.

Accurately measuring carbon dioxide is becoming increasingly important, especially for implementing on-demand ventilation systems.

On-demand ventilation systems are a solution currently being implemented in some parts of Europe, utilizing indoor carbon dioxide concentration data.nbsp;If applied to homes, schools, etc., it can reduce operating costs.

Infineon XENSIV™ PAS CO ₂ sensors are used in a variety of applications due to their accuracy, high performance, small size, relatively low price, and low power consumption compared to other sensors.

We hope that you will manage indoor air quality efficiently by utilizing the Infineon XENSIV™ PAS CO ₂ sensor.

thank you