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Abstract:
(Invited Talks)
Co-authors: Keith Albert, Todd Dickinson, John Kauer, Shannon
Stitzel, Joel White
Optical imaging fibers have are employed to create multi-analyte
sensor arrays. Sensing regions have been immobilized on the fiber's
distal tip. Thousands of individual sensors can be placed in the
array. Sensor arrays have been fabricated for simultaneous
multianalyte detection. This array format has been used to create
optical sensors based on principles derived from the olfactory
system. A cross-reactive array of sensors is created such that
specificity is distributed across the array's entire reactivity
pattern rather than contained in a single recognition element (see
figure). This approach has been demonstrated with a new vapor
sensing device that is designed as an array of optically-based
chemosensors providing input to a pattern recognition system
incorporating artificial neural networks. In the present device,
primary chemosensing input is provided by an array of fiber-optic
sensors. The individual sensors, which are broadly yet
differentially responsive, were prepared by immobilizing a
fluorescent indicator dye in polymer matrices of varying polarity,
hydrophobicity, pore size, elasticity,
and swelling tendency, creating unique sensing regions that
interact differently with vapor molecules. The fluorescent signals
obtained from each fiber sensor in response to applications of
different analyte vapors have unique temporal characteristics.
These temporal responses are used to train computational networks
for subsequent identification and quantification tasks. The array
also offers the ability to increase the detection sensitivity by
employing signal summing techniques that parallel the convergence
found in the olfactory system. The prospects for using such
technology to solve complex problems in medical diagnosis as well
as the ultimate potential for such systems to be applied to the way
humans interact with their environment will be discussed.
David R. Walt is Robinson Professor of Chemistry at Tufts
University. He received a B.S. in Chemistry from the University of
Michigan and a Ph.D. in Organic Chemistry and Pharmacology from
SUNY at Stony Brook. After postdoctoral studies at MIT, he joined
the chemistry faculty at Tufts. Professor Walt served as Chemistry
Department Chairman from 1989 to 1996. Dr. Walt serves on many
government advisory panels and boards and chaired a National
Research Council panel. He is Executive Editor of Applied
Biochemistry and Biotechnology and serves on the editorial advisory
board for the Journal of Combinatorial Chemistry.
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