Types & Applications of CO2 Sensor

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.

Photoacoustic Sensors

• 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.