Abstract
A photochemical polymerized optical pH-sensor system was fabricated. The portable sensor system consists of a blue LED for exciting the optical source and metal packaged photomultiplier tubes for detecting fluorescence. As an acidic indicator, Fluorescein sodium salt was used. Intensity of the fluorescent emission was proportional to the pH value of the acid solutions used. 5-Carboxyfluorescein was used for an alkaline indicator. However, intensity of the fluorescent emission was decreased as the pH value of the alkali solutions increased. We accomplished to measure pH from pH 3 to pH 10 by subtracting output voltages from two kinds of sensors. Using the pH multi-measuring system, we succeeded in pH-measurement during alkaline solutions are spreading.
