A carbon dioxide sensor, often known as a CO2 sensor, is a device used to measure carbon dioxide gas. Infrared gas sensors (NDIR) and chemical gas sensors are the two most popular types of CO2 sensors. With the use of a capnograph instrument, carbon dioxide measurement is crucial for assessing the quality of the air within buildings as well as for many industrial processes.
Nondispersive Infrared (NDIR) CO2 Sensors
- NDIR sensors are spectroscopic sensors that use CO2‘s distinctive absorption to find it in a gaseous environment. An infrared source, a light tube, an interference (wavelength) filter, and an infrared detector make up the essential parts. The electronics measure the absorption of the distinctive light wavelength as the gas is pushed into or diffuses into the light tube. The most popular use for NDIR sensors is carbon dioxide measurement.
- The amount of IR light received by the detector is divided by the amount of IR light radiated by the IR lamp. The difference is precisely proportional to the amount of CO2 molecules in the air sample tube since it results from the light’s absorption by the CO2 molecules inside the tube.
Chemical CO2 Sensors
- The main benefit of chemical CO2 gas sensors based on polymer- or heteropolysiloxane-sensitive layers is that they consume very little energy and can be made smaller to fit into microelectronic-based systems. In contrast to the NDIR measurement principle, the downsides of short- and long-term drift effects, as well as a relatively short total lifetime, pose significant challenges. The majority of CO2 sensors have a complete calibration before leaving the factory. To preserve the sensor’s long-term stability, the zero point needs to be adjusted over time.
- To calculate the amount of CO2 in the air, electrochemical carbon dioxide sensors monitor electrical current or conductivity.
- The sensor undergoes chemical reactions when CO2 is introduced. The sensor experiences an electrical change as a result of this reaction. The reaction may cause the sensor to pick up an electrical current, alter an existing current, or alter how well the sensor would carry a current, depending on the particular type of sensor. The sensor will then calculate the amount of CO2 present based on the type and amount of electrical change.
- By employing photoacoustic spectroscopy, CO2 may be quantified. By exposing a sample to electromagnetic energy pulses that are adjusted to the CO2‘s absorption wavelength, such as those produced by a distributed feedback laser[, the concentration of CO2 can be determined. The CO2 molecules in the sample will absorb each energy pulse and produce pressure waves as a result of the photoacoustic effect. After being picked up by an acoustic detector, these pressure waves are subsequently transformed into a useful CO2 reading by a computer or microprocessor.
- This is how the PAS concept operates. Light pulses from an infrared source pass through an optical filter set to the wavelength at which CO2 absorbs light (4.2 m or less). With each pulse, the CO2 molecules inside the measurement chamber shake and produce a pressure wave as a result of the filtered light being absorbed by the molecules. The term “photoacoustic effect” refers to this.
- The microprocessor interprets the output from the very sensitive MEMS acoustic detector, which measures the pressure change caused by CO2 molecules inside the sensor cavity. The acoustic detector is tuned for low-frequency operation and the absorption chamber is acoustically sealed to achieve the most precise ppm measurement possible.
Applications Of Sensors
- Some common applications for a CO2 detector are in monitoring indoor air quality, landfill, process control, and controlled environment horticulture.
- The Carbon Dioxide Sensor is used in Fruit Ripening.
- Volcano monitoring using a CO2 detector.
- Nuclear Applications Using a Carbon Dioxide Sensor.
- There is a Role of Carbon Dioxide Measurement in Wine Production.
- Stored Grains: Monitoring Carbon Dioxide Measurements for Early Spoilage Detection.
- CO2 Concentrations in the Processing of Pigs and Chickens.
- Carbon Dioxide Measurement’s Function in Sick Building Syndrome Prevention.