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High intensity light emitting diode array as an alternative exposure source for the fabrication of electrophoretic microfluidic devices


Breadmore, MC and Guijt, RM, High intensity light emitting diode array as an alternative exposure source for the fabrication of electrophoretic microfluidic devices, Journal of Chromatography A, 1213, (1) pp. 3-7. ISSN 0021-9673 (2008) [Refereed Article]

DOI: doi:10.1016/j.chroma.2008.09.094


A commercially available array of light emitting diodes (LEDs), namely a UV Shark series LED high flux array, was evaluated as a light source for photolithographic patterning of SU-8 photoresist for the fabrication of templates suitable to make poly(dimethylsiloxane) (PDMS) microchips for electrophoresis. At a distance of 15 cm from the substrate, a relatively even intensity of 0.76 ± 0.05 mW/cm2 was obtained over an area sufficient for patterning a 10 cm (4 in.) silicon wafer. The exposure source was evaluated using a spiral mask design covering a 10 cm wafer. PDMS replicates of this template made in a 25 μm thick layer of SU-8 3025 showed little variation in width over the surface of the substrate, with a variation of 3.2% RSD (n = 36) and a maximum range in widths of 7.8% of the mean channel width. The use of the optional metal reflector available with the LED array provided partial collimation of the light allowing near vertical structures to be produced across the entire wafer, something which was not possible without the reflector. SU-8 masters prepared using the LED array were compared to masters made using an alternative cheap lithographic source, namely a gel crosslinker. The SU-8 features were much narrower with the LED array than the crosslinker due to the multiple light sources in the crosslinker. A PDMS microchip made using a SU-8 template created using the Shark UV LED array was used for the electrophoretic separation of three anionic fluorescent dyes, with efficiencies up to 32 000 plates. Given that the LED array can be purchased and assembled for less than US$ 500, the Shark UV LED array is a promising alternative to more expensive lithographic light sources and will have significant appeal to many researchers wishing to undertake research in microfluidics around the world. © 2008.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Analytical chemistry
Research Field:Separation science
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Breadmore, MC (Professor Michael Breadmore)
UTAS Author:Guijt, RM (Dr Rosanne Guijt)
ID Code:55257
Year Published:2008
Web of Science® Times Cited:10
Deposited By:Chemistry
Deposited On:2009-03-06
Last Modified:2015-02-07

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