A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines the specific concentration of <i>Streptococcus mutans</i> in saliva, which is a major causative factor in dental caries. In this design, one prepares the fiber-optic bacterial sensor by replacing a portion of the cladding region of a multimode fiber with a dye-encapsulated xerogel, using the solgel technique. The exponential decay of the evanescent wave at the core-cladding interface of a multimode fiber is utilized for the determination of bacterial activity in saliva. The acidogenic profile of <i>Streptococcus mutans</i> is estimated by use of evanescent-wave absorption spectra at various levels of bacterial activity.
© 2002 Optical Society of America
(060.2310) Fiber optics and optical communications : Fiber optics
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(170.1850) Medical optics and biotechnology : Dentistry
(300.1030) Spectroscopy : Absorption
(300.6550) Spectroscopy : Spectroscopy, visible
M. Shelly John, Anil Kishen, Lim Chu Sing, and Anand Asundi, "Determination of bacterial activity by use of an evanescent-wave fiber-optic sensor," Appl. Opt. 41, 7334-7338 (2002)