Optical CO2 sensor of the combination of colorimetric change of α-naphtholphthalein in poly(isobutyl methacrylate) and fluorescent porphyrin in polystyrene

An optical CO2 sensor based on the overlay of the CO2 induced absorbance change of pH indicator dye a-naphtholphthalein in poly(isobutyl methacrylate) (polyIBM) layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 out increased with increasing the CO2 concentration. The ratio 11008() value of the sensing film consisting of alpha-naphtholphthalein in polyIBM and TPP in polystyrene layer, where I-0 and I-100 represent the detected luminescence intensities from a layer exposed to argon and CO2 saturated conditions, respectively, that the sensitivity of the sensor, is estimated to be 192. The response and recovery times of the sensing film are less than 6.0 s for switching from argon to CO2, and for switching from CO2 to argon. The signal changes are fully reversible and no hysterisis is observed during the measurements. The highly sensitive optical CO2 sensor based on fluorescence intensity changes of TPP due to the absorption change of alpha-naphtholphthalein in polylBM layer with CO2 is achieved. (c) 2005 Elsevier B.V. All rights reserved.