Recent development and applications of optical and fiber-optic pH sensors

This article provides a brief review on the development and applications of optical and fiber-optic pH sensors in the 1990s. Various methods and materials for immobilization of pH indicators are surveyed. Different spectroscopic methods used for measurement with pH sensors are briefly discussed. Several special optical and fiber-optic pH sensors ave reviewed, including pH sensors based on conductive polymers, imaging fibers, microparticles and nanospheres, as well as micron and sub-micron fiber-optic pH sensors, distributed fiber-optic pH sensors, pH sensors for high acidity and alkalinity, pH sensors with broad dynamic range and linear response, and CO2 and NH3 sensors based on pH indicators. Applications of fiberoptic sensors in environmental detection, biomedical research, medical monitoring and industrial process control are summarized. (C) 2000 Elsevier Science B.V. All rights reserved.