Carbon dioxide sensor: Difference between revisions
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{{distinguish|Carbon monoxide sensor}} |
{{distinguish|Carbon monoxide sensor}} |
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A '''carbon dioxide sensor''' or ''' |
A '''carbon dioxide sensor''' or '''{{CO2}} sensor''' is an instrument for the measurement of [[carbon dioxide]] gas. The most common principles for {{CO2}} sensors are infrared gas sensors ([[NDIR]]) and chemical gas sensors. Measuring carbon dioxide is important in monitoring [[indoor air quality]],<ref>{{Cite journal|last1=Kampezidou|first1=S. I.|last2=Tikayat Ray|first2=A.|last3= Duncan|first3=S. |last4= Balchanos |first4=M.G. |last5= Mavris |first5=D.N. |date=2021-01-07|title=Real-time occupancy detection with physics-informed pattern-recognition machines based on limited CO<sub>2</sub> and temperature sensors|journal= Energy and Buildings|volume=242|pages=110863|doi=10.1016/j.enbuild.2021.110863|s2cid=233831299|issn=0378-7788|doi-access=free}}</ref> the function of the lungs in the form of a [[capnograph]] device, and many industrial processes. |
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== Nondispersive infrared (NDIR) |
== Nondispersive infrared (NDIR) {{CO2}} sensors == |
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[[File:CO2Mini monitor TFA Dostmann.jpg|thumb|{{CO2}} concentration meter using a [[nondispersive infrared sensor]]]] |
[[File:CO2Mini monitor TFA Dostmann.jpg|thumb|{{CO2}} concentration meter using a [[nondispersive infrared sensor]]]] |
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{{main|Nondispersive infrared sensor}} |
{{main|Nondispersive infrared sensor}} |
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{{see also|Capnography}} |
{{see also|Capnography}} |
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[[NDIR]] sensors are [[spectroscopy|spectroscopic]] sensors to detect |
[[NDIR]] sensors are [[spectroscopy|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 measure the absorption of the characteristic [[wavelength]] of light. NDIR sensors are most often used for measuring carbon dioxide.<ref name="Lang">{{cite journal |last=Lang |first=T. |last2=Wiemhöfer |first2=H.D. |last3=Göpel |first3=W. |title=Carbonate based CO<sub>2</sub> sensors with high performance |journal=Sensors and Actuators B: Chemical |volume=34 |issue=1-3 |pages=383–7 |date=1996 |doi=10.1016/S0925-4005(96)01846-1 }}</ref> The best of these have sensitivities of 20–50 [[parts per million|PPM]].<ref name="Lang"/> Typical NDIR sensors cost in the (US) $100 to $1000 range. |
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NDIR |
NDIR {{CO2}} sensors are also used for dissolved {{CO2}} for applications such as beverage carbonation, pharmaceutical fermentation and [[carbon dioxide capture and storage|{{CO2}} sequestration]] applications. In this case they are mated to an ATR (attenuated total reflection) optic and measure the gas ''in situ''. New developments include using [[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).<ref>{{cite journal |last1=Vincent |first1=T.A. |last2=Gardner |first2=J.W. |title=A low cost MEMS based NDIR system for the monitoring of carbon dioxide in breath analysis at ppm levels |journal=Sensors and Actuators B: Chemical |date=November 2016 |volume=236 |pages=954–964 |doi=10.1016/j.snb.2016.04.016 |url=https://www.researchgate.net/publication/301241843}}</ref> |
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Another method ([[Henry's Law]]) also can be used to measure the amount of dissolved |
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.{{explain|date=August 2014}} |
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== Photoacoustic sensors == |
== Photoacoustic sensors == |
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{{CO2}} can be measured using [[photoacoustic spectroscopy]]. Concentration of {{CO2}} can be measured by subjecting a sample to pulses of electromagnetic energy (such as from a [[distributed feedback laser]]<ref>{{Cite thesis|last=Zakaria|first=Ryadh|title=NDIR Instrumentation Design for CO<sub>2</sub> Gas Sensing|type=PhD|date=March 2010|pages=35–36 |chapter=3.5 Photoacoustic Spectroscopy (PAS) |chapter-url=https://dspace.lib.cranfield.ac.uk/bitstream/handle/1826/6784/Ryad_Adbdullah_Zakaria_Thesis_2010.pdf |publisher=Cranfield University |hdl=1826/6784}}</ref>) 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.<ref>{{Cite web|last=AG|first=Infineon Technologies|title={{CO2}} Sensors - Infineon Technologies|url=https://www.infineon.com/cms/en/product/sensor/co2-sensors/|access-date=2020-11-10|website=www.infineon.com}}</ref> |
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== Chemical |
== Chemical {{CO2}} sensors== |
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Chemical |
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.<ref name="Zhou">{{cite journal |last=Zhou |first=R. |last2=Vaihinger |first2=S. |last3=Geckeler |first3=K.E. |last4=Göpel |first4=W. |title=Reliable CO<sub>2</sub> sensors with silicon-based polymers on quartz microbalance transducers |journal=Sensors and Actuators B: Chemical |volume=19 |issue=1-3 |pages=415–420 |date=1994 |doi=10.1016/0925-4005(93)01018-Y }}</ref> 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.<ref>{{cite web |title=CO<sub>2</sub> Auto-Calibration Guide|url=http://sstsensing.com/sites/default/files/AN0117_4_CO2SensorAutoCalibrationNote.pdf |access-date=2014-08-19 |url-status=dead |archive-url=https://web.archive.org/web/20140819214423/http://sstsensing.com/sites/default/files/AN0117_4_CO2SensorAutoCalibrationNote.pdf |archive-date=2014-08-19 }}</ref> |
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== Estimated |
== Estimated {{CO2}} sensor == |
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For indoor environments such as offices or gyms where the principal source of |
For indoor environments such as offices or gyms where the principal source of {{CO2}} is human [[Respiration (physiology)|respiration]], rescaling some easier-to-measure quantities such as [[volatile organic compound]] (VOC) and [[hydrogen gas]] ({{chem2|H2}}) concentrations provides a good-enough estimator of the real {{CO2}} concentration for ventilation and occupancy purposes.{{Citation needed|date=January 2022}} Furthermore, inasmuch as ventilation is a factor in the spread of respiratory [[virus]]es,<ref>{{cite journal | doi=10.1146/annurev-virology-012420-022445 | title=Seasonality of Respiratory Viral Infections | journal=Annual Review of Virology | date=29 September 2020 | volume=7 | issue=1 | pages=83–101 | last1=Moriyama | first1=Miyu | last2=Hugentobler | first2=Walter J. | last3=Iwasaki | first3=Akiko | pmid=32196426 | s2cid=214601321 | doi-access=free }}</ref> {{CO2}} levels are a rough metric for [[COVID-19]] risk; the worse the ventilation, the better for viruses and ''vice versa''.<ref>{{cite journal | doi=10.1021/acs.estlett.1c00183 | title=Exhaled CO 2 as a COVID-19 Infection Risk Proxy for Different Indoor Environments and Activities | journal=Environmental Science & Technology Letters | date=11 May 2021 | volume=8 | issue=5 | pages=392–397 | last1=Peng | first1=Zhe | last2=Jimenez | first2=Jose L. | pmid=37566374 | pmc=8043197 | bibcode=2021EnSTL...8..392P }}</ref><ref>https://www.sciencedaily.com/releases/2021/04/210407143809.html {{Bare URL inline|date=September 2022}}</ref> Sensors for these substances can be made using cheap (~$20) [[Microelectromechanical systems]] (MEMS) [[metal oxide semiconductor]] (MOS) technology. The reading they generate is called estimated {{CO2}} (e{{CO2}})<ref name="pmid29614746">{{cite journal|last1=Rüffer|first1=D|last2=Hoehne|first2=F|last3=Bühler|first3=J|date=31 March 2018|title=New Digital Metal-Oxide (MOx) Sensor Platform.|journal=Sensors (Basel, Switzerland)|volume=18|issue=4|page=1052|doi=10.3390/s18041052|pmc=5948493|pmid=29614746|bibcode=2018Senso..18.1052.|doi-access=free}}</ref> or {{CO2}} equivalent ({{CO2}}eq).<ref name="voc" /> 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. H<sub>2</sub>-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.<ref name=voc>{{cite journal |title=MOS gas sensor technology for demand controlled ventilation |journal=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 |date=2009 |url=https://www.aivc.org/sites/default/files/members_area/medias/pdf/Conf/2009/AIVC_Herberger_fullpaper_engl.pdf |location=Berlin |vauthors=Herberger S, Herold M, Ulmer H}}</ref> |
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== Applications == |
== Applications == |
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** [[Rebreather]]s (SCUBA) |
** [[Rebreather]]s (SCUBA) |
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** [[Decaffeination]] |
** [[Decaffeination]] |
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* For indoor human [[Occupancy sensor|occupancy counting]]<ref>{{Cite journal|last1=Arief-Ang|first1=I.B.|last2=Hamilton|first2=M.|last3=Salim|first3=F.|date=2018-06-01|title=RUP: Large Room Utilisation Prediction with carbon dioxide sensor|journal=Pervasive and Mobile Computing|volume=46|pages=49–72|doi=10.1016/j.pmcj.2018.03.001|s2cid=13670861 |issn=1873-1589}}</ref><ref>{{Cite book|last1=Arief-Ang|first1=I.B.|last2=Salim|first2=F.D.|last3=Hamilton|first3=M. |chapter=SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series |series=Communications in Computer and Information Science |date=2018-04-14|volume=845 |title=Data Mining|trans-title=SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series|publisher=Springer |
* For indoor human [[Occupancy sensor|occupancy counting]]<ref>{{Cite journal|last1=Arief-Ang|first1=I.B.|last2=Hamilton|first2=M.|last3=Salim|first3=F.|date=2018-06-01|title=RUP: Large Room Utilisation Prediction with carbon dioxide sensor|journal=Pervasive and Mobile Computing|volume=46|pages=49–72|doi=10.1016/j.pmcj.2018.03.001|s2cid=13670861 |issn=1873-1589}}</ref><ref>{{Cite book|last1=Arief-Ang|first1=I.B.|last2=Salim|first2=F.D.|last3=Hamilton|first3=M. |chapter=SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series |series=Communications in Computer and Information Science |date=2018-04-14|volume=845 |title=Data Mining|trans-title=SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series|publisher=Springer|pages=125–143|doi=10.1007/978-981-13-0292-3_8|isbn=978-981-13-0291-6}}</ref> |
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* For [[HVAC]] applications, |
* For [[HVAC]] applications, {{CO2}} sensors can be used to monitor the quality of air and the tailored need for fresh air, respectively. Measuring {{CO2}} levels indirectly determines how many people are in a room, and ventilation can be adjusted accordingly. See [[Demand-controlled ventilation|demand controlled ventilation (DCV)]].<ref>{{cite web |title=Demand Control Ventilation Benefits for Your Building |date=2013 |publisher=KMC Controls |url=https://web.archive.org/web/20140627030355/http://www.kmccontrols.com/docs/DCV_Benefits_White_Paper_KMC_RevB.pdf}}</ref> |
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Following are too vague and generic, should be explained or deleted |
Following are too vague and generic, should be explained or deleted |
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Latest revision as of 08:01, 25 April 2024
A carbon dioxide sensor or CO2 sensor is an instrument for the measurement of carbon dioxide gas. The most common principles for CO2 sensors are infrared gas sensors (NDIR) and chemical gas sensors. Measuring carbon dioxide is important in monitoring indoor air quality,[1] the function of the lungs in the form of a capnograph device, and many industrial processes.
Nondispersive infrared (NDIR) CO2 sensors[edit]
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 measure the absorption of the characteristic wavelength of light. NDIR sensors are most often used for measuring carbon dioxide.[2] The best of these have sensitivities of 20–50 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 CO2 sequestration applications. In this case they are mated to an ATR (attenuated total reflection) optic and measure the gas in situ. New developments include using 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[edit]
CO2 can be measured using photoacoustic spectroscopy. Concentration of CO2 can be measured by subjecting a sample to pulses of electromagnetic energy (such as from a 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[edit]
Chemical CO2 gas sensors with sensitive layers based on polymer- or heteropolysiloxane 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[edit]
For indoor environments such as offices or gyms where the principal source of CO2 is human respiration, rescaling some easier-to-measure quantities such as volatile organic compound (VOC) and hydrogen gas (H2) concentrations provides a good-enough estimator of the real CO2 concentration for ventilation and occupancy purposes.[citation needed] Furthermore, inasmuch as ventilation is a factor in the spread of respiratory viruses,[8] CO2 levels are a rough metric for COVID-19 risk; the worse the ventilation, the better for viruses and vice versa.[9][10] Sensors for these substances can be made using cheap (~$20) Microelectromechanical systems (MEMS) 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[edit]
- Examples:
- Modified atmospheres
- Indoor air quality
- Stowaway detection
- Cellar and gas stores
- Marine vessels
- Greenhouses
- Landfill gas
- Confined spaces
- Aerospace
- Healthcare
- Horticulture
- Transportation
- Cryogenics
- Ventilation management
- Mining
- Rebreathers (SCUBA)
- Decaffeination
- For indoor human occupancy counting[13][14]
- For HVAC applications, CO2 sensors can be used to monitor the quality of air and the tailored need for fresh air, respectively. Measuring CO2 levels indirectly determines how many people are in a room, and ventilation can be adjusted accordingly. See demand controlled ventilation (DCV).[15]
See also[edit]
References[edit]
- ^ Kampezidou, S. I.; Tikayat Ray, A.; Duncan, S.; Balchanos, M.G.; Mavris, D.N. (2021-01-07). "Real-time occupancy detection with physics-informed pattern-recognition machines based on limited CO2 and temperature sensors". Energy and Buildings. 242: 110863. doi:10.1016/j.enbuild.2021.110863. ISSN 0378-7788. S2CID 233831299.
- ^ a b Lang, T.; Wiemhöfer, H.D.; Göpel, W. (1996). "Carbonate based CO2 sensors with high performance". Sensors and Actuators B: Chemical. 34 (1–3): 383–7. doi:10.1016/S0925-4005(96)01846-1.
- ^ Vincent, T.A.; Gardner, J.W. (November 2016). "A low cost MEMS based NDIR system for the monitoring of carbon dioxide in breath analysis at ppm levels". Sensors and Actuators B: Chemical. 236: 954–964. doi:10.1016/j.snb.2016.04.016.
- ^ Zakaria, Ryadh (March 2010). "3.5 Photoacoustic Spectroscopy (PAS)" (PDF). NDIR Instrumentation Design for CO2 Gas Sensing (PhD). Cranfield University. pp. 35–36. hdl:1826/6784.
- ^ AG, Infineon Technologies. "CO2 Sensors - Infineon Technologies". www.infineon.com. Retrieved 2020-11-10.
- ^ Zhou, R.; Vaihinger, S.; Geckeler, K.E.; Göpel, W. (1994). "Reliable CO2 sensors with silicon-based polymers on quartz microbalance transducers". Sensors and Actuators B: Chemical. 19 (1–3): 415–420. doi:10.1016/0925-4005(93)01018-Y.
- ^ "CO2 Auto-Calibration Guide" (PDF). Archived from the original (PDF) on 2014-08-19. Retrieved 2014-08-19.
- ^ Moriyama, Miyu; Hugentobler, Walter J.; Iwasaki, Akiko (29 September 2020). "Seasonality of Respiratory Viral Infections". Annual Review of Virology. 7 (1): 83–101. doi:10.1146/annurev-virology-012420-022445. PMID 32196426. S2CID 214601321.
- ^ Peng, Zhe; Jimenez, Jose L. (11 May 2021). "Exhaled CO 2 as a COVID-19 Infection Risk Proxy for Different Indoor Environments and Activities". Environmental Science & Technology Letters. 8 (5): 392–397. Bibcode:2021EnSTL...8..392P. doi:10.1021/acs.estlett.1c00183. PMC 8043197. PMID 37566374.
- ^ https://www.sciencedaily.com/releases/2021/04/210407143809.html [bare URL]
- ^ Rüffer, D; Hoehne, F; Bühler, J (31 March 2018). "New Digital Metal-Oxide (MOx) Sensor Platform". Sensors (Basel, Switzerland). 18 (4): 1052. Bibcode:2018Senso..18.1052.. doi:10.3390/s18041052. PMC 5948493. PMID 29614746.
- ^ 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.
- ^ Arief-Ang, I.B.; Hamilton, M.; Salim, F. (2018-06-01). "RUP: Large Room Utilisation Prediction with carbon dioxide sensor". Pervasive and Mobile Computing. 46: 49–72. doi:10.1016/j.pmcj.2018.03.001. ISSN 1873-1589. S2CID 13670861.
- ^ Arief-Ang, I.B.; Salim, F.D.; Hamilton, M. (2018-04-14). "SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series". Data Mining [SD-HOC: Seasonal Decomposition Algorithm for Mining Lagged Time Series]. Communications in Computer and Information Science. Vol. 845. Springer. pp. 125–143. doi:10.1007/978-981-13-0292-3_8. ISBN 978-981-13-0291-6.
- ^ "Demand Control Ventilation Benefits for Your Building" (PDF). KMC Controls. 2013.