Carbon dioxide sensor

Source: Wikipedia, the free encyclopedia.
Not to be confused with
Carbon monoxide sensor
.

A carbon dioxide sensor or CO2 sensor is an instrument for the measurement of

capnograph
device, and many industrial processes.

Nondispersive infrared (NDIR) CO2 sensors

CO2 concentration meter using a nondispersive infrared sensor
Main article: Nondispersive infrared sensor
See also: Capnography

PPM.[2]
Typical NDIR sensors cost in the (US) $100 to $1000 range.

NDIR CO2 sensors are also used for dissolved CO2 for applications such as beverage carbonation, pharmaceutical fermentation and

microelectromechanical systems (MEMS) IR sources to bring down the costs of this sensor and to create smaller devices (for example for use in air conditioning applications).[3]

Another method (

Henry's Law) also can be used to measure the amount of dissolved CO2 in a liquid, if the amount of foreign gases is insignificant.[further explanation needed
]

Photoacoustic sensors

CO2 can be measured using

distributed feedback laser[4]) that is tuned specifically to the absorption wavelength of CO2. With each pulse of energy, the CO2 molecules within the sample will absorb and generate pressure waves via the photoacoustic effect. These pressure waves are then detected with an acoustic detector and converted to a usable CO2 reading through a computer or microprocessor.[5]

Chemical CO2 sensors

Chemical CO2 gas sensors with sensitive layers based on polymer- or hetero

polysiloxane have the principal advantage of very low energy consumption, and that they 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.[6] Most CO2 sensors are fully calibrated prior to shipping from the factory. Over time, the zero point of the sensor needs to be calibrated to maintain the long term stability of the sensor.[7]

Estimated CO2 sensor

For indoor environments such as offices or gyms where the principal source of CO2 is human

metal oxide semiconductor (MOS) technology. The reading they generate is called estimated CO2 (eCO2)[11] or CO2 equivalent (CO2eq).[12] Although the readings tend to be good enough in the long run, introducing non-respiration sources of VOC or CO2, such as peeling fruits or using perfume, will undermine their reliability. H2-based sensors are less susceptible as they are more specific to human breathing, although the very health conditions the hydrogen breath test is set to diagnose will also disrupt them.[12]

Applications

See also

References

  1. S2CID 233831299
    .
  2. ^
    doi:10.1016/S0925-4005(96)01846-1
    .
  3. doi:10.1016/j.snb.2016.04.016
    .
  4. hdl:1826/6784
    .
  5. ^ AG, Infineon Technologies. "CO2 Sensors - Infineon Technologies". www.infineon.com. Retrieved 2020-11-10.
  6. doi:10.1016/0925-4005(93)01018-Y
    .
  7. ^ "CO2 Auto-Calibration Guide" (PDF). Archived from the original (PDF) on 2014-08-19. Retrieved 2014-08-19.
  8. S2CID 214601321
    .
  9. PMID 37566374
    .
  10. ^ https://www.sciencedaily.com/releases/2021/04/210407143809.html [bare URL]
  11. PMID 29614746
    .
  12. ^ a b Herberger S, Herold M, Ulmer H (2009). "MOS gas sensor technology for demand controlled ventilation" (PDF). Proceedings of the 4th International Symposium on Building and Ductwork Air Tightness and 30th AIVC Conference on Trends in High Performance Buildings and the Role of Ventilation. Berlin.
  13. S2CID 13670861
    .
  14. ISBN 978-981-13-0291-6
    .
  15. ^ "Demand Control Ventilation Benefits for Your Building" (PDF). KMC Controls. 2013.
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