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A split microchannel design and analytical model to compensate for electroosmotic instabilities in micro-separations
Jennifer Monahan1, Kari A Fosser, Andrew A Gewirth
1Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, IL 61801, USA.
Lab on a Chip
|April 22, 2004
Summary
This study introduces a split-channel microfluidic device to stabilize electroosmotic flow (EOF) in polymer-based systems. The design enhances analyte mobility measurements, reducing variability from ca. 20% to 1% for more reliable electrophoretic separations.
Area of Science:
- Analytical Chemistry
- Microfluidics
- Polymer Science
Background:
- Organic polymers are advantageous for microfluidic devices but often exhibit unstable electroosmotic flow (EOF).
- Instability in EOF complicates quantitative analysis and reproducibility in microfluidic separations.
Purpose of the Study:
- To develop a microfluidic device design that compensates for electroosmotic flow variations.
- To improve the quantitative comparability and reduce variability in electrophoretic separations within polymer microchannels.
Main Methods:
- A split-channel microfluidic device was designed, dividing analyte plugs into two channels of different lengths.
- Channels were recombined for single-point detection, eliminating the need for scanning detection systems.
- Analyte migration times were internally referenced between the two channels to correct for flow drift.
Main Results:
- The split-channel design eliminated the need for a separate electroosmotic flow marker.
- Analyte mobilities were quantitatively comparable across multiple devices and runs.
- Relative standard deviations in analyte mobilities were reduced from ~20% to ~1%.
Conclusions:
- The split-channel microfluidic device effectively compensates for electroosmotic flow drift in polymer chips.
- This internal standardization method enhances the precision and reliability of electrophoretic separations.
- The design mitigates the need for strict environmental monitoring (temperature, pH) during separations.