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Fiber-Optic Chemical Sensors 829

surfaces and measuring local chemical concentrations. the near future, advanced multianalyte fiber-optic chemi-
Corrosion monitoring of a copper/aluminum galvanic pair cal sensors will be able to accomplish real-time measure-
has been demonstrated. Cathodic and anodic reactions ments for various analytical applications.
change the local pH. These processes were investigated
with a pH-sensitive sensor array by measuring the pH-
induced fluorescence changes occurring where the sensor SEE ALSO THE FOLLOWING ARTICLES
contacted the metal surface. Such optical sensor arrays re-
duce the precision with which an extremely small probe ABSORPTION • ANALYTICAL CHEMISTRY • BIOMATE-
must be positioned and offer major advantages over mi- RIALS,SYNTHESIS,FABRICATION, AND APPLICATIONS •
croelectrode arrays in both ease of fabrication and mea- ENVIRONMENTAL MEASUREMENTS • ENVIRONMENTAL
surement on the micrometer scale. TOXICOLOGY • ENZYME MECHANISMS • NUCLEIC
ACID SYNTHESIS • OPTICAL FIBERS,FABRICATION
AND APPLICATION • OPTICAL FIBER TECHNIQUES FOR
VI. CONCLUSIONS MEDICAL APPLICATIONS • RAMAN SPECTROSCOPY

Fiber-optic chemical sensors offer several advantages over
other sensing technologies based on the unique character- BIBLIOGRAPHY
istics of optical fibers. The principal advantages include
their immunity to harsh environmental conditions (e.g., Culshaw, B., and Dakin, J. (eds.). (1997). “Optical Fiber Sensors (Com-
ponents and Subsystems),” Vol. 3, Artech House, Norwood, MA.
electromagnetic interference, high temperature, high pH)
Dakin, J., and Culshaw, B. (eds.). (1997). “Optical Fiber Sensors (Ap-
and their ability to function without any direct electrical plications, Analysis, and Future Trends),” Vol. 4, Artech House,
connection to the sample. These features have resulted in Norwood, MA.
the development of different fiber-optic chemical sensors Lin, J. (2000). “Recent development and applications of optical and
for analytical applications in the clinical, environmental, fiber-optic pH sensors,” Trends. Anal. Chem. 19, 541–552.
and industrial fields. Mehrvar, M., Bis, C., Scharer, J. M., Moo-Young, M., and Luong, J. H.
(2000). “Fiber-optic biosensors—trends and advances,” Anal. Sci. 16,
Recently, optical fibers have attracted attention mainly
677–692.
due to their use in telecommunications. New technologies Rogers, A. (1999). “Distributed optical-fiber sensing,” Meas. Sci. Tech-
have been developed for fabricating optical fibers with nol. 10, R75–R99.
very efficient light transmission capabilities. Fibers can Rogers, K. R., and Poziomek, E. J. (1996). “Fiber optic sensors for
transmit very high amounts of information. In fiber-optic environmental monitoring,” Chemosphere 33, 1151–1174.
Walt, R. D. (1998). “Fiber optic imaging sensors,” Acc. Chem. Res. 31,
chemical sensors, this information can be different ana-
267–278.
lytical signals resulting from different sensing elements Wolfbeis, O. S. (2000). “Fiber-optic chemical sensors and biosensors,”
located at the end of an optical fiber. It is expected that in Anal. Chem. 72, 81R–89R.