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Proceedings Paper

The role of electro-osmosis and dielectrophoresis in collection of micro/nano size particles in low frequency AC electric field
Author(s): Chehung Wei; Che-Wei Hsu; Ching-Chieh Wang
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Paper Abstract

The collecting and sorting micro size particles by electric force is easy to integrate with other bioassays. There are many forms of electric forces such as electrophoresis, dielectrophoresis and electroosmosis which can be used to manipulate particles. In an attempt to understand the role of electroosmosis and dielectrophoresis in the collection of micro size particles, a small device made of two parallel plates is used to study the particle movement under AC electric field. The device is fabricated by a top electrode and a bottom electrode separated by a spacer. The top electrode is made from an ITO glass where the bottom electrode is made of Corning 1737 glass sputtered with chromium. A dielectric layer is fabricated by spin coating a thin photo-resist (0.5~1μm) on the bottom electrode and a spacer made of curing PDMS is utilized to separate these electrodes. A 900μm × 900μm collecting chamber is fabricated on the bottom electrode via photolithography. The amine-modified polystyrene fluorescent particles whose average size is 1 μm were used for collection experiments. Different frequency and power were applied to generate the non-uniform electric field. It was found that frequency is the critical factor for electroosmotic velocity. There seems to be an optimum frequency that leads to largest particle velocity. The underlying mechanism is believed to the competing forces among dielectrophoresis and electroosmosis. This device demonstrates that the electroosmosis force is suitable for collecting bio-particles in AC electric field.

Paper Details

Date Published: 11 September 2007
PDF: 10 pages
Proc. SPIE 6645, Nanoengineering: Fabrication, Properties, Optics, and Devices IV, 664528 (11 September 2007); doi: 10.1117/12.735185
Show Author Affiliations
Chehung Wei, Tatung Univ. (Taiwan)
Che-Wei Hsu, Tatung Univ. (Taiwan)
Ching-Chieh Wang, Tatung Univ. (Taiwan)

Published in SPIE Proceedings Vol. 6645:
Nanoengineering: Fabrication, Properties, Optics, and Devices IV
Elizabeth A. Dobisz; Louay A. Eldada, Editor(s)

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