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Determination of bacterial activity by use of an evanescent-wave fiber-optic sensor
M Shelly John1, Anil Kishen, Lim Chu Sing
1School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798.
Abstract:
A novel technique based on fiber-optic evanescent-wave spectroscopy is proposed for the detection of bacterial activity in human saliva. The sensor determines th e specific concentration of Streptococcus mutans 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 Streptococcus mutans is estimated by use of evanescent-waveabsorption spectra at various levels of bacterial activity.