Fast-response carbon dioxide sensor

The sensor for the measurement of high levels of CO2 in gas phase was developed, as well90. It was based on fluorescence resonance energy transfer between 0 long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye were both immobilized in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix. The sensor exhibited a fast and reversible response to carbon dioxide over a wide range of concentrations. 

Expired air contains 2 to 5% carbon dioxide Although most carbon dioxide optodes are known to be particularly slow in response, the response time of this kind of sensor is less than 0 3 s (I) for 90% of the total signal change to occur. This is obviously due to the very thin coating. Such a fast response makes it possible to instrumentally monitor the concentration of carbon dioxide in respiratory air, but also to visually observe the continuous color change (from blue to yellow and back) while breathing through the capillary... 

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