Rapid responsible optical CO2 sensor of the combination of colorimetric change of α-naphtholphthalein in poly(trimethylsiliylpropyne) layer and internal reference fluorescent porphyrin in polystyrene layer

An optical CO 2 sensor based on the overlay of the CO 2 induced absorbance change of pH indicator dye α-naphtholphthalein in poly(trimethylsiliypropyne) (poly(TMSP))layer with the fluorescence of tetraphenylporphyrin (TPP) in polystyrene layer is developed. The observed luminescence intensity from TPP at 655 nm increased with increasing the CO 2 concentration. The ratio I 100 / I 0 value of the sensing film, where I 0 and I 100 represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO 2 , respectively, that the sensitivity of the sensor, is estimated to be 10.3. The response and recovery times of the sensing film are less than 3.0 s for switching from argon to CO 2 , and for switching from CO 2 to argon. The signal changes are fully reversible and no hysteresis is observed during the measurements. The highly sensitive and fast responsible optical CO 2 sensor based on fluorescence intensity changes of TPP due to the absorption change of α-naphtholphthalein with CO 2 is achieved using poly(TMSP) film.