Carbon dioxide sensor

Nondispersive Infrared (NDIR) CO2 Sensors
NDIR sensors are spectroscopic sensors to detect CO2 in a gaseous environment by its characteristic absorption. The key components are an infrared source, a light tube, an interference (wavelength) filter, and an infrared detector. The gas is pumped or diffuses into the light tube, and the electronics measures the absorption of the characteristic wavelength of light. NDIR sensors are most often used for measuring carbon dioxide. The best of these have sensitivities of 20-50 PPM. Typical NDIR sensors are still in the (US) $100 to $1000 range. New developments include using Microelectromechanical systems to bring down the costs of this sensor and to create smaller devices (for example for use in air conditioning applications).
Chemical CO2 Sensors
Chemical CO2 gas sensors with sensitive layers based on polymer- or heteropolysiloxane have the principal advantage of a very low energy consumption and can be reduced in size to fit into microelectronic-based systems. On the downside, short- and long term drift effects as well as a rather low overall lifetime are major obstacles when compared with the NDIR measurement principle.
Applications
For air conditioning applications these kind of sensors can be used to monitor the quality of air and the tailored need of fresh air, respectively.
In applications where direct temperature measurement is not applicable NDIR sensors can be used. The sensors absorb ambient infrared radiation (IR) given off by a heated surface.
See also
List of sensors
References
^ a b Carbonate Based CO2 Sensors with High Performance, Th. Lang, H.-D. Wiemhfer and W. Gpel, Conf.Proc.Eurosensors IX, Stockholm (S) (1995); Sensors and Actuators B, 34, 1996, 383-387.
^ Reliable CO2 Sensors Based with Silicon-based Polymers on Quartz Microbalance Transducers, R. Zhou, S. Vaihinger, K.E. Geckeler and W. Gpel, Conf.Proc.Eurosensors VII, Budapest (H) (1993); Sensors and Actuators B, 18-19, 1994, 415-420.
Categories: Sensors | Gas sensors

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