How does Amphenol measure CO2? Amphenol’s CO2 product use non-dispersive infrared (NDIR) technology to directly and accurately measure the concentration of CO2 in the air. NDIR works based on the fact that CO2 molecules absorb a specific wavelength of infrared light. By measuring the absorbed light, the sensor can make a very precise measurement of CO2 concentration. Additionally, Amphenol’s CO2 sensors incorporate a patented self-calibration algorithm called ABC Logic which is used to keep the sensors calibrated over time.