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Single potential electrophoresis microchip with reduced bias using pressure pulse injection
Frédéric Lacharme1, Martin A M Gijs
1Institute of Microelectronics and Microsystems, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland. Frederic.Lacharme@epfl.ch
Electrophoresis
|April 28, 2006
Summary
We developed new pressure injection techniques for electrophoresis microchips, offering controlled, reproducible sample introduction with minimal bias. These methods improve sample handling in microfluidic devices.
Area of Science:
- Microfluidics
- Analytical Chemistry
- Biotechnology
Background:
- Traditional electrokinetic injection in microchips can introduce sample bias.
- Reproducible sample introduction is crucial for accurate microchip electrophoresis analysis.
Purpose of the Study:
- To introduce and evaluate two novel pressure-based injection techniques for microchip electrophoresis.
- To demonstrate reduced injection bias and improved sample composition control compared to electrokinetic methods.
Main Methods:
- Developed front gate and back gate pressure injection variants using PDMS membrane deflection.
- Utilized a fluorescein/rhodamine B solution in Tris/boric acid buffer for testing.
- Applied a constant voltage (3 kV) for electrokinetic sample pre-concentration.
Main Results:
- Pressure-based injection resulted in nearly constant sample composition, indicated by stable peak area ratios.
- The new techniques provide controlled and reproducible sample plug injection.
- A minor bias at short injection times was observed, attributed to electrical field effects.
Conclusions:
- Front gate and back gate pressure injection are effective alternatives to electrokinetic injection.
- These methods enhance the reliability and accuracy of microchip electrophoresis.
- Further optimization can minimize residual injection bias for advanced applications.