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Optical Engineering

Simple apparatus for polarization sensing of analytes
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Paper Abstract

We describe a simple device for fluorescence sensing based on an unexpansive light source, a dual photocell and a Watson bridge. The emission is detected from two fluorescent samples, one of which changes intensity in response to the analyte. The emission from these two samples is observed through two orthogonally oriented polarizers and an analyzer polarizer. The latter polarizer is rotated to yield equal intensities from both sides of the dual photocell, as determined by a zero voltage from the Watson bridge. Using this device, we are able to measure fluorescein concentration to an accuracy near 2% at 1 ?M fluorescein, and pH values accurate to ±0.02 pH units. We also use this approach with a UV hand lamp and a glucose-sensitive protein to measure glucose concentrations near 2 ?M to an accuracy of ±0.1 ?M. This approach requires only simple electronics, which can be battery powered. Additionally, the method is generic, and can be applied with any fluorescent sample that displays a change in intensity. one can imagine this approach being used to develop portable point-of-care clinical devices.

Paper Details

Date Published: 1 September 2000
PDF: 8 pages
Opt. Eng. 39(9) doi: 10.1117/1.1286521
Published in: Optical Engineering Volume 39, Issue 9
Show Author Affiliations
Zygmunt Gryczynski, Univ. of Maryland School of Medicine/Baltimore (United States)
Ignacy Gryczynski, Univ. of Maryland School of Medicine/Baltimore (United States)
Joseph R. Lakowicz, Univ. of Maryland (United States)

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