How Do CO2 Sensors Work?

Carbon dioxide (CO2) is a colorless, odorless gas that is formed during respiration, combustion, and organic decomposition. It is also an extremely useful process gas with wide cross-market applicability. Measuring carbon dioxide is important in monitoring combustion processes, environmental CO2 emission levels, indoor air quality, the function of the lungs in medical procedures, and for a wide variety of applications in many industrial sectors including agri-food, pharmaceutical, brewing, beverage, and refrigeration.
Carbon dioxide is typically measured using nondispersive infrared (NDIR) or electrochemical technology. Improvements to NDIR-based carbon dioxide sensors have made it the most common solution for measuring CO2 concentrations with better accuracy across extremely wide ranges up to 100% volume.

How NDIR CO2 Sensors Work

NDIR CO2 sensors monitor and detect for the presence of carbon dioxide based on the absorption of infrared light at a specific wavelength.
An NDIR sensor comprises an infrared source, a light tube, a bandpass filter, and a detector. The target gas is determined through the filter wavelength choice. For CO2, the most commonly used wavelength is 4.26 µm. This wavelength is not absorbed at all by other commonly found gases or by water vapor which greatly reduces cross-sensitivities and impact to moisture and humidity.
Normal operation of an NDIR CO2 sensor involves the gas being pumped or diffused into the light tube. The electronics then measure the absorption of the characteristic wavelength of light. The amount of light absorption is converted into an electrical output that provides a parts per million (ppm) or % volume measurement. Simply put, the more light absorbed equates to more target gas molecules present which results in a lower output signal and inversely higher reported CO2 concentration.

Sensor Operation with No Gas Present	Sensor Operation with Gas Present

Benefits of PST CO2 Sensors

NDIR CO2 sensors have performance advantages over other detection technologies by providing enhanced long-term stability, accuracy, and low power consumption for CO2 measurement.

Process Sensing Technologies is a world leader in the design and manufacturer of NDIR CO2 sensors. These miniature sensors can fit neatly inside compact devices with long-lasting durability and reliability to ensure consistent performance over long a service life. We offer ultra-efficient and extremely reliable NDIR CO2 sensors that respond to carbon dioxide concentrations ranging from 500 parts per million up to 100% volume.

Want to learn more? Contact a member of the PST sales team today for full product specifications, or with any questions about your specific application requirements.