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Electrokinetic molecular separation in nanoscale fluidic channels
Anthony L Garcia1, Linnea K Ista, Dimiter N Petsev
1Department of Mechanical Engineering, Albuquerque, New Mexico 87131, USA.
Lab on a Chip
|October 20, 2005
Summary
Electrokinetic transport in nanochannels shows anomalous separation of charged molecules due to nanoconfinement. This study establishes a clear distinction between nano- and microfluidic regimes for molecular separation.
Area of Science:
- Physics
- Chemistry
- Engineering
Background:
- Electrokinetic phenomena are crucial for microfluidic and nanofluidic devices.
- Understanding solute behavior in nanochannels is key for developing advanced separation technologies.
Purpose of the Study:
- To investigate electrokinetic transport of molecular mixtures in integrated macro- to nano-fluidic chips.
- To analyze the influence of nanoconfinement on solute separation.
- To establish a distinction between nano- and microfluidic transport regimes.
Main Methods:
- Fabrication of high-aspect-ratio nanochannels on Si wafers using interferometric lithography.
- Confocal laser scanning microscopy to observe electrokinetic transport of charged and neutral dyes.
- Application of electric fields below 2000 V m-1 in nanochannels ranging from 35 to 200 nm width.
Main Results:
- Negatively charged dye exhibited higher electroosmotic velocity than neutral dye in negatively charged nanochannels due to nanoconfinement and wall interactions.
- Anomalous separation of dyes was observed over short distances (<1 mm).
- Increasing channel width shifted electroosmotic transport behavior, differentiating nano- and microfluidic regimes.
Conclusions:
- Nanoconfinement significantly alters electrokinetic transport compared to microfluidic systems.
- An analytical model accurately predicts experimental observations, including solute adsorption.
- The findings suggest potential for novel nano-separation technologies.