LINEAR-RESPONSE FUNCTION FOR FLUORESCENCE-BASED FIBEROPTIC CO2 SENSORS

The theoretical basis and experimental evidence for a Stern-Volmer type relationship using the fluorescence ratio (I-bl/I) in the absence (I-bl) and presence (I) of CO2 as response function for fluorescence-based fiber-optic CO2 sensors is explored. By choosing the right indicator, appropriate bicarbonate concentration, and a thin enough sensing layer, a fiber-optic CO2 sensor with a usable linear range can be easily achieved using I-bl/I as the response function. This allows the possibility of one-point calibration, which cannot be accomplished if the measured fluorescence intensity (I) is used directly as the response function.