A ratiometric pH-sensitive fluorescent dye (hydroxypyrenetrisulfonic acid) was covalently attached to an acrylamide polymer. These pH-sensitive copolymers were either covalently bonded to the end of an optical fiber or polymerized into separate gels. Long-term, accelerated aging studies were performed on the fibers and gels in 43°C distilled H20. The fiber-immobilized optrodes gave good pH responses for up to 2 months. The pH-sensitive gels were physically attached to optical fibers and gave very good pH responses for over one year. These physically immobilized, one-year-old, pH-sensitive copolymers provided optrodes with linear pH responses between pH 6 and 8 and resolution greater than 0.25 pH unit. A simple photostability experiment on these optrodes showed that they were very photostable. The results of this study indicate that pH-sensitive copolymers in a simple optrode design can be employed as pH sensors with useful lifetimes exceeding one year.

Date Published: 1 July 1990
PDF: 7 pages
Proc. SPIE 1201, Optical Fibers in Medicine V, (1 July 1990); doi: 10.1117/12.17561

Published in SPIE Proceedings Vol. 1201:
Optical Fibers in Medicine V
Abraham Katzir, Editor(s)