This high-precision sensor is perfect for Raspberry Pi & Arduino enthusiasts, engineers, hobbyists, and anyone interested in home, lab, field, and storage applications of atmospheric co2, temperature, and relative humidity sensing. The SCD-41 works by emitting a light source into a sample chamber, where it is absorbed by the CO2 molecules present. The resulting pressure change is detected by an ultra-sensitive microphone. The number of CO2 molecules is proportional to the pressure change.