An optical sensor with the combination of colorimetric change of α-naphtholphthalein and internal reference luminescent dye for CO_2 in water

摘要

A new optical CO_2 sensor based on luminescence intensity changes of tetraphenylporphyrin (TPP) due to the absorption change of pH indicator dye (α-naphtholphthalein) with CO_2 is developed and its CO_2 sensing properties in pure water are investigated. The observed luminescence intensity from TPP at 650nm increased with increasing the CO_2 concentration in pure water. The ratio I_(100)/I_0, where I_0, and I_(100) represent the detected luminescence intensities from a layer exposed to 100% argon and 100% CO_2, respectively, that we takes the sensitivity of the sensor is estimated to be 430. The response times of the sensing film are 42.6 s for switching from argon to CO_2, and 88.8 s tor switching from CO_2 to argon in pure water. The signal changes are fully reversible and no hysterisis is observed during the measurements.