Vaisala CARBOCAP® Technology


First launched in 1997, the Vaisala CARBOCAP® carbon dioxide (CO2) sensor features a groundbreaking innovation – the micromachined, electrically tunable Fabry-Perot Interferometer (FPI) filter for built-in reference measurement. This reliable and stable sensor has been delivering accurate CO2 measurements since the late 1990s across a wide range of industries and applications, from building automation and safety to life sciences and ecological research.

How It Works

Carbon dioxide has a characteristic absorbance band in the infrared (IR) region at a wavelength of 4.26 μm. This means that when IR radiation is passed through a gas containing CO2, part of the radiation is absorbed. Therefore, the amount of radiation passing through the gas depends on the amount of CO2 present, and this can be detected with an IR detector.

The Vaisala CARBOCAP® sensor features an electrically tunable FPI filter. In addition to measuring CO2 absorption, the micromechanical FPI filter enables a reference measurement at a wavelength where no absorption occurs. When taking the reference measurement, the FPI filter is electrically adjusted to switch the bypass band from the absorption wavelength to a nonabsorption wavelength. The reference  measurement compensates for any potential changes in the light source intensity, as well as for contamination and dirt accumulation in the optical path. This feature means that CARBOCAP® sensor operation is highly stable over time. Instruments measuring at both the absorption and the reference wavelength with a single light source are known as single-beam dual-wavelength instruments. The technology is widely applied in costly analyzers. The unique feature of the CARBOCAP® sensor is its micromachined FPI filter, which performs a dual-wavelength measurement using a single detector. The compact size of the sensor means that this advanced technology can be incorporated into small probes, modules, and transmitters.

Vaisala Carbocap technology sensor illustration


Typical Applications for Carbon Dioxide Measurement

Vaisala CARBOCAP® instruments are well suited to a wide range of applications, from ppm (parts per million) to percentage-level CO2 measurements. Since CO2 replaces oxygen, it can be harmful to people in very high concentrations. CO2 is present at percentage levels only within closed processes such as fermentation and controlled-atmosphere storage environments. Percentage-level measurements are also typical in life-science applications such as CO2 incubation.

Normal atmospheric air includes CO2 at ppm levels. Typical CARBOCAP® applications include ventilation control in buildings occupied by people, animal shelters, and greenhouses. In areas where large volumes of CO2 are handled, reliable CO2 measurement with alarm control is an important safety precaution.The CARBOCAP® sensor is also a popular choice in ecological measurement applications, where excellent long-term stability and tolerance to harsh conditions are important requirements.

CARBOCAP® CO2 Products

Vaisala offers instruments for measuring CO2 at ppm and percentage levels in both indoor and outdoor environments. Vaisala's wide variety of CO2 instruments ranges from hand-held meters, measurement modules, and industrial transmitters to high-volume, affordable transmitters for volume applications.


Spring chicks
Typical CARBOCAP® applications include ventilation control in animal shelters.



Watch the video

Vaisala CARBOCAP Technology

CARBOCAP® Technology Inside

Vaisala uses a single-beam and dual-wavelength NDIR (Non-dispersive infrared) technology for measuring CO2, The patented CARBOCAP® technology is used in all our CO2 sensors. This technology incorporates a unique tunable band pass filter that was developed by Vaisala and is manufactured in our own state-of-the-art cleanroom.  View this video to find out why it's unique and why it makes the Vaisala CO2 measurement the most reliable and accurate one on the market or learn more on our carbon dioxide page.

Products using CARBOCAP® Technology

GM20 Series Carbon Dioxide Transmitters

CO₂ Transmitter Series GM20

for Demand Controlled Ventilation
The duct-mounted Vaisala CARBOCAP® Carbon Dioxide Transmitter Series GMD20 are specially designed for demand-controlled ventilation (DCV). They are...
Handheld CO2 meter GM70

Handheld CO₂ Meter GM70

for Spot-Checking Applications
The Vaisala CARBOCAP® Hand-held Carbon Dioxide Meter GM70 measures volume concentration of CO2 in the units of ppm or %. It is a user-friendly meter...
GMP343 Carbon Dioxide Probe

CO₂ Probe GMP343

for Demanding Measurements
The Vaisala CARBOCAP® Carbon Dioxide Probe GMP343 is an accurate and rugged probe-type instrument for ecological measurements. Typical applications...
GMP231 CARBOCAP® Carbon Dioxide Probe

CO₂ Probe GMP231

for CO₂ Incubators
The Vaisala CARBOCAP® Carbon Dioxide Probe GMP231 is designed to provide incubator manufacturers with accurate and reliable carbon dioxide...
CO2 Probe is suitable for agriculture, refrigeration, greenhouses, demanding HVAC applications, and for plant growth chamber manufacturers

CO₂ Probe GMP252

for ppm-level measurements in agriculture, refrigeration, demanding HVAC, and for plant growth manufacturers
The Vaisala CARBOCAP® Carbon Dioxide Probe GMP252 is an intelligent, stand-alone, ppm-level probe. It's intended for measuring CO2 in agriculture...
 Vaisala CARBOCAP® Carbon Dioxide Probe GMP251

CO₂ Probe GMP251

for %-level measurements in life science incubators, cold storage facilities and all demanding applications
The Vaisala CARBOCAP® Carbon Dioxide Probe GMP251 is an intelligent, stand-alone, %-level probe for measuring CO2 in life science incubators, cold...