Biomedical Microdevices

, Volume 8, Issue 3, pp 209–214

Sensitivity enhancement for colorimetric glucose assays on whole blood by on-chip beam-guidance

  • M. Grumann
  • J. Steigert
  • L. Riegger
  • I. Moser
  • B. Enderle
  • K. Riebeseel
  • G. Urban
  • R. Zengerle
  • J. Ducrée
Article

DOI: 10.1007/s10544-006-8172-x

Cite this article as:
Grumann, M., Steigert, J., Riegger, L. et al. Biomed Microdevices (2006) 8: 209. doi:10.1007/s10544-006-8172-x

Abstract

In this paper, we present a novel concept for optical beam-guidance to significantly enhance the sensitivity of colorimetric assays by extending the optical path length through the detection cell which linearly impacts the resulting attenuation of a probe beam according to the law of Beer-Lambert. In our setup, the incident probe beam is deflected by 90 into the chip plane at monolithically integrated V-grooves to pass a flat detection cell at its full width (i.e., with a path length of 10 mm) instead of its usually much smaller height. Afterwards, the attenuated beam is redirected by another V-groove towards an external detector. The general beam-guidance concept is demonstrated by a glucose assay on human whole blood on a centrifugal microfluidic “lab-on-a-disk” platform made of COC. We achieve an excellent linearity with a correlation coefficient (R2) of 0.997 paired with a lower limit of detection (200 μM) and a good reproducibility with a coefficient of variation (CV) of 4.0% over nearly three orders of magnitude. With an accelerated sedimentation of cellular constituents by centrifugal forces, the sample of whole blood can be analyzed in a fully integrated fashion within 210 s. This time-to-result can even be improved by the numerical extrapolation of the saturation value. Additionally, the direct assay on whole blood also shows a negligible correlation with the hematocrit of the blood sample.

Keywords

GlucoseOptical beam-guidanceLab-on-a-diskColorimetric assayTotal internal reflection

Copyright information

© Springer Science + Business Media, LLC 2006

Authors and Affiliations

  • M. Grumann
    • 1
  • J. Steigert
    • 1
  • L. Riegger
    • 1
  • I. Moser
    • 2
  • B. Enderle
    • 2
  • K. Riebeseel
    • 2
  • G. Urban
    • 2
  • R. Zengerle
    • 1
  • J. Ducrée
    • 1
  1. 1.Lab for MEMS ApplicationsIMTEK—University of FreiburgFreiburgGermany
  2. 2.Lab for SensorsIMTEK—University of FreiburgFreiburgGermany