CO2 sensors are a type of product used to monitor the concentration of carbon dioxide. As people begin to pay more attention to indoor air quality, the CO2 concentration indoors has become one of the key indicators to determine whether the air quality is qualified or not. If the carbon dioxide content in the environment exceeds a certain level, physical discomforts and even poisoning would occur on human bodies. So carbon dioxide sensors are widely used to optimize our production and life, such as detecting the CO2 content in agricultural greenhouses to ventilate in time and increase crop yields, and monitoring the concentration of carbon dioxide in mines to ensure the safety of workers, etc.

The working principle of CO2 sensors is as follows. Infrared light with a certain intensity and wavelength hits the air and will be absorbed by carbon dioxide. And receiving tube outputs the corresponding electrical signal by detecting the intensity of the absorbed infrared light. The sensor internally filters and amplifies the electrical signal, and the MCU calculates the concentration of carbon dioxide in the air through an algorithm. Among such sensors, the CO2 sensors with the infrared principle are the most widely used. They possess good selectivity, no oxygen dependence, long service life and high precision, and are not easily be interfered by the environment. Therefore, they play an important role in the petrochemical industry, atmospheric monitoring, medical care, smart agriculture and other fields.

When using a CO2 sensor for carbon dioxide concentration monitoring, the following aspects need to be paid attention to. First, measuring range. In general, the default measurement range of CO2 sensors is 0-5000ppm. However, on some agricultural occasions, when the respiration of the crop is intense, the CO2 concentration might exceed 5000ppm. Second, waterproofing. The carbon dioxide sensor has a gas-permeable membrane, so the device is not waterproof. Third, environment temperature. The working temperature of the CO2 sensor is -10-50℃. If it is exceeded, measurement errors will occur.