Optical pH Sensor Based on Polyaniline Sol-Gel Film Immobilized with Bromothymol Blue and Phenol Red

摘要

Optical absorption spectra of dye doped in polyaniline (PANI) sol-gel films for sensing of pH solutions have been investigated. Accordingly, the glass substrate was coated by dip coating by sol-gel method. The surface morphological and optical characterizations of the deposited films were carried out using Atomic Force Microscopy (AFM) and UV-Vis spectroscopy respectively. The PANI thin film's surface shows high grain with RMS around 26.33nm. The surface of thin film doped with bromothymol blue and phenol red is more regular with large cavities with RMS value around 70.32nm and 39.44nm respectively. Two absorption bands with absorption peak located at 428nm and 619nm are found for bromothymol blue films while 430nm and 554nm for phenol red films. Both dye-doped deposited films are found bromothymol blue is more sensitive to pH environment and show good reversibility.