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Issue 16, 2009
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Expansion channels for low-pass filtering of axial concentration gradients in microfluidic systems

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Abstract

Chemical gradients that run axially in a microfluidic channel often contain undesirable high-frequency concentration variations, or noise, that results from mechanical and thermal fluctuations in the system. In this paper, we describe a passive microfluidic component called an ‘expansion channel’ (EC), that removes high frequency noise through axial dispersion. We show that the behavior of the filter can be modeled analytically, using an expression for the transfer function of the microfluidic channel, derived by Xie et al. (Y. W. Xie, L. Chen and C. H. Mastrangelo, Lab Chip, 2008, 8, 907–912). The use of ECs to remove noise from gradients formed in enyzmatic assays in a microfluidic channel is demonstrated. The resulting data quality is improved which enables better fits to chemical models and more accurate analysis. ECs should be very effective in removing noise from axial concentration gradients found in many microfluidic applications, e.g.liquid chromatography, biochemistry, and chemotaxis studies.

Graphical abstract: Expansion channels for low-pass filtering of axial concentration gradients in microfluidic systems

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Publication details

The article was received on 03 Feb 2009, accepted on 14 May 2009 and first published on 03 Jun 2009


Article type: Paper
DOI: 10.1039/B902291K
Citation: Lab Chip, 2009,9, 2332-2338
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    Expansion channels for low-pass filtering of axial concentration gradients in microfluidic systems

    D. M. Hartmann, J. T. Nevill, D. Wyrick, G. A. Votaw and H. C. Crenshaw, Lab Chip, 2009, 9, 2332
    DOI: 10.1039/B902291K

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