Special Section on Theory and Practice of MEMS/NEMS/MOEMS, RF MEMS, and BioMEMS

Single-stranded DNA concentration by electrokinetic forces

[+] Author Affiliations
Han Cheng

The Hong Kong Polytechnic University, Research Institute of Innovative Products and Technologies, Hung Hom, Kowloon, Hong Kong

Kin Fong Lei

The Hong Kong Polytechnic University, Research Institute of Innovative Products and Technologies, Hung Hom, Kowloon, Hong Kong

Kit Ying Choy

The Hong Kong Polytechnic University, Department of Applied Biology and Chemical Technology, Hung Hom, Kowloon, Hong Kong

Larry M. C. Chow

The Hong Kong Polytechnic University, Department of Applied Biology and Chemical Technology, Hung Hom, Kowloon, Hong Kong

J. Micro/Nanolith. MEMS MOEMS. 8(2), 021107 (June 09, 2009). doi:10.1117/1.3152003
History: Received August 15, 2008; Revised April 20, 2009; Accepted April 24, 2009; Published June 09, 2009
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Electrokinetics provide an effective molecular manipulation technique in micro/nano fluidic environments, which match the length scale of various biological objects. In this work, two circular gold electrodes are fabricated on a glass substrate as DNA concentrators. A combination of alternating current (ac) electro-osmosis and electrophoresis is used to concentrate single-stranded DNA (ssDNA) molecules as small as 20 nucleotides in length. To understand the phenomenon of ac electro-osmotic flow, numerical simulation of the flow field is done and shows that the effective fluid flow is up to 100μm above the electrode surface. Hence, ssDNA molecules labeled with fluorescent dye are utilized to demonstrate the concentration effect on the DNA concentrator. ac electro-osmotic flow induced by the ac electric field can stir the bulk fluid, and ssDNA molecules can be transported from a large effective region to the surface of DNA concentrator. In addition, electrophoretic force induced by direct current (dc) bias is applied simultaneously to attract and hold ssDNA molecules. The motion of ssDNA molecules under electrokinetic forces is observed under a fluorescence microscope. The experimental results show that the ssDNA molecules can be concentrated on the electrode surface instantly. ssDNA concentration under different conditions is also compared and the results generated are discussed.

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© 2009 Society of Photo-Optical Instrumentation Engineers

Citation

Han Cheng ; Kin Fong Lei ; Kit Ying Choy and Larry M. C. Chow
"Single-stranded DNA concentration by electrokinetic forces", J. Micro/Nanolith. MEMS MOEMS. 8(2), 021107 (June 09, 2009). ; http://dx.doi.org/10.1117/1.3152003


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