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Proceedings Paper

Optical chromatography in a PDMS microfluidic environment
Author(s): Alex V. Terray; Sean J. Hart; Katherine L. Kuhn; Jonathan Arnold
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Paper Abstract

Since the discovery that laser radiation could be used to impart momentum to microscopic entities, a wide variety of methods, devices, and applications have followed. The most well known method for harnessing optical pressure, optical trapping, involves the highly convergent diffraction limited focusing of a laser for optical manipulation. A lesser known method, termed optical chromatography, involves mildly focusing a laser propagating directly against a fluid flow. When microscopic particles in the flow path encounter this beam they are trapped axially along the beam and are pushed upstream from the focal point to rest at a point where the optical pressure and fluid forces on the particle are equal. Because the optical and fluid forces are sensitive to differences in the physical and chemical properties of a particle, a new level of sensitivity, discrimination, and control is possible. This method has recently been used to separate colloidal particles differing only in refractive index. Flow environments designed and fabricated in poly(dimethylsiloxane) (PDMS) using a modification to the method termed Soft Lithography have been adapted to accommodate a loosely focused laser beam entering through a sidewall of the PDMS microfluidic system. Optical chromatographic separations, active sorting, and other particulate mixture manipulations within these customized PDMS microfluidic channel systems are being investigated. The application of these methods and the design of fluidic and optical environments will allow for the very specific separation, identification, and manipulation of a multitude of microscopic particle suspensions.

Paper Details

Date Published: 18 October 2004
PDF: 9 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.557890
Show Author Affiliations
Alex V. Terray, Geo-Centers, Inc. (United States)
Sean J. Hart, Naval Research Lab. (United States)
Katherine L. Kuhn, Naval Research Lab. (United States)
Jonathan Arnold, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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