CO2SENSORSMathew NapierASEN 4519/5519Project PresentationIntroduction• Why measure CO2?– If levels become to high CO2begins to act as asphyxiant. – A general indicator of indoor air quality.– High levels can enhance plant growth. • Places that CO2sensors are used?– Confined work spaces– Brewing and carbonated drink industries– Controlled plant growthTypes of CO2Sensors• Mass Airflow sensors– thermal conductivity• Solid state electrochemical sensors• Mixed oxide sensors• Ion selective membrane sensors• Optical sensorsWhy Optical Method?• Inert nature of CO2makes it difficult to measure with sensors that depend on chemical reactions.• Optical sensors are not affected by dust, water vapor or most chemicals.Single Beam NDIR CO2Sensor• Narrow bandpass filter is used to select the absorption wavelength of CO2. • Sensor consists of an IR source, gas sample cell, optical filter, and IR detector•CO2 concentration is measured by measuring the amount of IR passing through the sample cell to the detector.CARBOCAP® CO2Sensor• NDIR Single-Beam Dual-Wavelength.• Tunable Filter is a Fabry-Perot Interferometer made in silicon.• Ratio of IR measured in the absorption band and reference band gives CO2concentration• Eliminates drift, small, cost and effectiveCO2SensorsGMT220GMM220• VAISALA GMM220 & GMT220• Measurement Ranges– variable from 0 to 7000ppm– variable from 0 to 20 %• Sampling Technique– diffusion• GMT 220 is LonWorks compatible.Future Technology• In Situ Biosafe Fiber Optic CO2Sensor for Real-Time Bioreactor Monitoring.• Intelligent Fiber Optic Systems (IFOS)– porous glass optical fiber sensing substrate sections– biosafe carbon-dioxide-sensitive fluorescent indicators– Superb short-wavelength semiconductor optical sources• Fluorescence of the indicator in the fiber depends on CO2concentration.New Technology Continued• The proposed sensor system responds to NASA’s need for new techniques for real-time monitoring of bioreactors for biotechnology/medical applications in space/microgravity sciences.• Potential benefits/advantages– high sensitivity, dynamic range, stability,speed biosafety, and biocompatibility – Electrically passive, low-power, low-weight, compact, inline, low-cost and mass-producibleConclusion •CO2Sensors are used in a wide range of applications and industries.• NDIR type CO2sensors are most common and reliable on the market.• IFOS type sensors are the future not only CO2sensors but all types of biotechnology sensors.Refrences• http://www.vaisala.com/WWW/webcom.NSF/1…c2e0b5ace9c2256421005b3155?OpenDocument• http://es.epa.gov/ncerqa_abstracts/sbir/other/monana/moslehi.html• http://www.vaisala.com/WWW/webcom.NSF/1…cabece7d0ac2256421004b4a72?OpenDocument• http://www.vaisala.com/WWW/webcom.NSF/1…d0434d629ec2256790002841c5?OpenDocument• http://www.vaisala.com/WWW/webcom.NSF/1…c87df319d8c225681100389573?OpenDocument• http://www.honeywell.com/sensing/prodinfo/massairflow/• http://www.vaisala.com/WWW/webcom.NSF/1…4d380bbb1cc225643e0032cec9?OpenDocument• http://www.vaisala.com/WWW/webcom.NSF/1…42776f3b66c226421004b5b9a?OpenDocument•
View Full Document