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Simulation and experimental characterization of electroosmotic flow in surface modified channels

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Abstract

Covalent surface modification techniques, in particular surface oxidation procedures, have been employed as a mean to modify polymer microfluidic channels for the purpose of modulating microflow. The focus of this work is to experimentally and computationally characterize electroosmotic flow (EOF) to understand the impact of surface modifications and buffer pH on sample mixing and dispersion. The experimental results are used to calibrate and validate the simulation model that solves the Navier–Stokes equation for fluid flow and Poisson equation to resolve external electric field. Experimental and simulated results are presented for hybrid microfluidic systems, consisting of both pristine polymer surfaces and chemically modified polymer surfaces. The results show that the selective surface modification induces hydrodynamic pressure gradient, leading to enhanced sample dispersion. The mass flow rate increases linearly with the level of oxidation. All channels (pristine, oxidized, and hybrid) showed an increasing EOF with increasing pH until the near neutral regime (7<pH<9), where the EOF leveled off at a maximum value—behavior that is typical of a microchannel with negative surface moieties populating its surface.

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Acknowledgments

The authors gratefully acknowledge support from DARPA/DSO under the SYMBIOSIS program (Project Monitor: Dr. Anantha Krishnan). A.C.H. would like to acknowledge the support of the National Research Council/National Institute of Standards and Technology Post-Doctoral Research Program. Certain commercial equipment, instruments, or materials are identified in this report to specify adequately the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

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Authors and Affiliations

  1. CFD Research Corporation, 215 Wynn Drive, Suite 501, Huntsville, AL, 35805, USA

    S. Krishnamoorthy, J. Feng & S. Sundaram

  2. National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, 20899, MD, USA

    A. C. Henry & L. E. Locascio

  3. University of Central Florida, Nanoscience Technology Center, 12424 Research Parkway, Suite 400, Orlando, FL, 32816, USA

    J. J. Hickman

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  1. S. Krishnamoorthy
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  2. J. Feng
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  3. A. C. Henry
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  4. L. E. Locascio
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  5. J. J. Hickman
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  6. S. Sundaram
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Correspondence to S. Krishnamoorthy.

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Krishnamoorthy, S., Feng, J., Henry, A.C. et al. Simulation and experimental characterization of electroosmotic flow in surface modified channels. Microfluid Nanofluid 2, 345–355 (2006). https://doi.org/10.1007/s10404-006-0077-8

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  • DOI: https://doi.org/10.1007/s10404-006-0077-8

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