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Analytical Methods. Issue 12, 2012.
Daisuke Onoshima, Jun Wang, Michihiko Aki, Kenji Arinaga, Noritada Kaji, Manabu Tokeshi, Shozo Fujita, Naoki Yokoyama, Yoshinobu Babaa.
FIRST Research Center for Innovative Nanobiodevices, Nagoya University, Nagoya, Japan .
E-mail: [email protected].
Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, Goteborg, Sweden.
Fujitsu Laboratories Ltd, Atsugi, Japan.
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan.
Division of Biotechnology and Macromolecular Chemistry, Faculty of Engineering, Hokkaido University, Sapporo, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Japan.
Abstract
Dry film resist SU-8 was used to make a thick mold for soft lithography of a poly(dimethylsiloxane) (PDMS) microfluidic chip with deep channels. The stacking of the SU-8 film enabled an ultra-thick (up to 500 um) resist process on Si wafer. This process was fast and highly reproducible compared with the conventional liquid SU-8 process. The deep channel in the PDMS chip was utilized as a micro-flow cell for sensitive absorbance measurement. Sunset Yellow FCF dye was used to demonstrate absorption spectroscopy in the deep channel. Since the channel depth was proportional to the optical path length, which was proportional to the absorbance value, the PDMS chip achieved a detection limit (15.9 uM) comparable to U- or Z-shaped microfabricated absorbance detection cells in glass. Calibration curves for different solution concentrations were obtained with good R2 values (1).
