Notice

You are currently browsing the website for customers from San Marino. We recommend switching to the United States version of the site, optimized for your region.
San Marino
€ EUR
Prices without VAT

SCD4x - The Smallest CO2 Sensor

Sensirion sensors SCD40 and SCD41 broke the size barrier and are the smallest CO2 sensors currently available. They measure only 10x10x7 mm, which is 10 times less than other CO2 sensors.
This is an archive article published 04/15/2021. Some information may no longer be up to date and in line with the current state. Please contact us in case of interest.

How Is It Possible?

SCD4x works on the photoacoustic principle.

SCD4x - The Smallest CO2 Sensor
The measuring chamber (inner space of the sensor) is periodically irradiated with infrared light with a wavelength corresponding to the absorption band of CO2 molecules (4.2 ... 4.4um).

The CO2 molecules in the measuring chamber absorb part of the radiation. The absorbed energy of the CO2 molecules excites mainly molecular vibrations, which leads to increased translational energy of the molecules and, due to the closed measuring chamber, to a periodic change of pressure in the chamber, which is measured by a microphone.
Molecules of other gases do not absorb infrared radiation of this wavelength and do not contribute to the change in pressure in the measuring chamber.

SCD4x - The Smallest CO2 Sensor

Changes in pressure are proportional to (number CO2 molecules) / (chamber volume). The more CO2 molecules are present in the measuring cell, the greater the pressure changes and the microphone’s output voltage. If we halve the volume of the measuring chamber, the number of CO2 molecules will also be halved, but the pressure changes will remain the same so that the sensitivity of the sensor will not change.

The sensitivity of the NDIR sensor is proportional to fractional absorbance

FA = 1-e ^ (- klx)

  • k is the absorption coefficient for the specific gas and filter combination
  • l is the equivalent optical path length between the lamp and detectors 
  • x is the concentration of the gas.

The FA can be plotted against x, as shown in the figure below. The FA value increases with x, but saturation occurs at high gas concentrations.

SCD4x - The Smallest CO2 Sensor

To measure concentration in range, let’s say 0 to 10 000 ppm (1%), we can choose k*l around 50, which leads to FA = 0,049 at 1 000 ppm. If we halve the length of the optical path, then k*l = 25 => FA = 0,025. The sensitivity at 1 000 ppm decreased by 49%.

Comparison of SCD30 and SCD4x

SCD4x - The Smallest CO2 Sensor

How to Start with SCD4x

You will need SEK-SCD41-Sensor, SEK-SensorBridge and ControlCenter software for your Windows, Linux or Mac PC.

We have included both Sensirion CO2 sensors, SCD40 and SCD41, in our stock range.

If you need more information about Sensirion products, please contact our sales representative for your region or send us an email to sensirion@soselectronic.com; we will be happy to help you.

Do not miss these articles

Do you like our articles? Do not miss any of them! You do not have to worry about anything, we will arrange delivery to you.

Related articles

Main products

SCD40-D-R1 SENSIRION
SENSIRION

Ord.number: 338284

in stock 445 pcs

SCD40-D-R1

Gas Sensors

Calibrated CO2 Sensor

1 pcs+ 24,90 €

10 pcs+ 22,30 €

60 pcs+ 18,50 €

120 pcs+ 17,20 €

180 pcs+ 16,40 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare
SCD41-D-R1 SENSIRION
SENSIRION

Ord.number: 347339

in stock 572 pcs
(11/29/2024: 120 pcs)
(12/20/2024: 240 pcs)
(01/10/2025: 400 pcs)
(01/17/2025: 120 pcs)

SCD41-D-R1

Gas Sensors

Calibrated CO2 Sensor

1 pcs+ 36,70 €

10 pcs+ 31,80 €

30 pcs+ 30,00 €

60 pcs+ 29,10 €

120 pcs+ 28,00 €

180 pcs+ 26,30 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare
SEK-SCD41-Sensor SENSIRION
SENSIRION

Ord.number: 347353

in stock 14 pcs

SEK-SCD41-Sensor

Development Tools

SCD41-D on the PCB with SensorBridge cable and jumper wire set

1 pcs+ 57,20 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare
SEK-SensorBridge SENSIRION
SENSIRION

Ord.number: 313470

in stock 22 pcs

SEK-SensorBridge

Development Tools

Base Unit for SEK-XXX-Sensors

1 pcs+ 68,50 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare

Additional products

SCD40-D-R2 SENSIRION
SENSIRION

Ord.number: 347334

SCD40-D-R2

Gas Sensors

Calibrated CO2 Sensor

600 pcs+ 16,60 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare
SCD41-D-R2 SENSIRION
SENSIRION

Ord.number: 347342

SCD41-D-R2

Gas Sensors

Calibrated CO2 Sensor

600 pcs+ 22,40 €

  • ADD TO CART
  • Get Quote
  • Add to favorites
  • Add to watchdog
  • Add item to compare
Do you agree with cookies being stored?
Welcome to the SOS electronic website. Before you enter our online world, we would like to ask you to allow us to store cookies on your browser. Your consent will help us view the site without error, measure its performance, and track additional statistics. Apart from that, we can bring you an offer of our products and services, literally tailor-made. We also provide cookies to third parties. However, you are definitely safe with us.
The proper operation of the website
More stable technical control
Better marketing offer
Necessary Only selected Accept all cookies
Change the settings
Country
Select the country you are located in to receive relevant information and services tailored to your region.
Choose a language
Select your preferred language for displaying website content and communicating with our support.
Currency
Select the currency in which you want to see product prices. This way, we ensure you see current prices tailored to your needs.
Show prices with VAT
Select whether you want to display prices with or without VAT to have a better overview of costs.
Prices without VAT Prices incl. VAT