Analytical and Bioanalytical Chemistry

, Volume 395, Issue 2, pp 473–478 | Cite as

Application of external micro-spectrophotometric detection to improve sensitivity on microchips

  • Attila GáspárEmail author
  • István Bácsi
  • Erika F. Garcia
  • Mihály Braun
  • Frank A. Gomez
Original Paper


The goal of this work was to increase the sensitivity of a UV–Vis spectrophotometer by decreasing the background noise and lengthening the optical path. A microphotometer has been modified to precisely select very small parts of a microfluidic channel pattern of a chip and to measure light absorbance on a magnified area of the selected part of the channel. The viability of combining a projection microscope and a spectrophotometer for external absorbance measurements on disposable PDMS chips was studied. Besides the external direct detection above a microfluidic channel, the optical pathlength was lengthened by detecting in the region of the perpendicular exit port. Increasing the cross-sectional area of the zone of irradiation improved the signal-to-noise ratio and the limits of detection (LOD).


Chip Poly(dimethylsiloxane) External UV detection Micro-spectrophotometer Flow injection Microfluidics/microfabrication UV/Vis 



The authors gratefully acknowledge financial support for this research by grants from the National Scientific Research Fund, Hungary K75286), the National Office for Research and Technology (Baross-2-2007-0028) and the National Science Foundation (DMR-0351848, CHE-0515363, and OISE-0754138).


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Attila Gáspár
    • 1
    Email author
  • István Bácsi
    • 2
  • Erika F. Garcia
    • 3
  • Mihály Braun
    • 1
  • Frank A. Gomez
    • 3
  1. 1.Department of Inorganic and Analytical ChemistryUniversity of DebrecenDebrecenHungary
  2. 2.Cetox LtdDebrecenHungary
  3. 3.Department of Chemistry and BiochemistryCalifornia State University, Los AngelesLos AngelesUSA

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