A highly sensitive and selective optical waveguide sensor based on a porphyrin-coated ZnO film

A highly sensitive and selective optical sensor device based on a porphyrin-coated ZnO thin film/K + ion-exchanged glass composite optical waveguide (COWG) layer was developed. The surface of the ZnO film was coated with a thin film of 5,10,15,20-tetrakis-(4-methoxyphenyl) porphyrin by the spin-coating or immersion method. The optical properties of the films were probed by UV–vis and Fourier-transform infrared spectroscopies. The gas sensing performance was also examined in detail. The high sensitivity, room temperature operation, good selectivity, and reproducibility of the sensor render it a promising candidate for industrial use and in environmental monitoring.