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Proceedings Paper

Fluorescence and absorbance analyte sensing in whole blood and plasma based on diffusion separation in silicon-microfabricated flow structures
Author(s): Bernhard H. Weigl; Greg T. Hixson; Margaret Kenny; Diane Zebert; Silver Dwinnell; Todd Buj; Paul Yager
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Paper Abstract

Based on the recently introduced T-Sensor method, we demonstrate the fluorescence-determination of various analytes directly in whole blood and in serum. The method relies on microfluidic flow in silicon structures, diffusion-based separation, and analyte determination using fluorescent and absorption indicator dyes. Due to extremely small inertial forces in such structures, practically all flow in microstructures is laminar. This allows the movement of different layers of fluid and particles next to each other in a channel without mixing other than by diffusion. A sample solution (e.g., blood), and a receptor solution containing the indicator dye are introduced in a common channel, and flow laminarly next to each other until they exit the structure. Small ions such as H+, and Na+ diffuse rapidly across the channel, whereas larger molecules diffuse more slowly. Larger particles such as blood cells and polymer beads show no significant diffusion within the time the two flow streams are in contact. The fluorescence emission of indicator dyes is a function of the concentration of the analyte molecules and the dye concentration in the interaction zone between the two streams. This device allows continuous monitoring of the concentration of analytes in whole blood without the use of membranes or prior removal of blood cells. This principle is illustrated by the determination of human albumin, total calcium, and pH in whole blood and serum.

Paper Details

Date Published: 7 May 1997
PDF: 11 pages
Proc. SPIE 2980, Advances in Fluorescence Sensing Technology III, (7 May 1997); doi: 10.1117/12.273526
Show Author Affiliations
Bernhard H. Weigl, Univ. of Washington (United States)
Greg T. Hixson, Univ. of Washington (United States)
Margaret Kenny, Univ. of Washington (United States)
Diane Zebert, Univ. of Washington (United States)
Silver Dwinnell, Univ. of Washington (United States)
Todd Buj, Univ. of Washington (United States)
Paul Yager, Univ. of Washington (United States)


Published in SPIE Proceedings Vol. 2980:
Advances in Fluorescence Sensing Technology III
Richard B. Thompson, Editor(s)

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