Electroosmotic Flow Reversal Outside Glass Nanopores
- Nadanai Laohakunakorn (1350075)
- Vivek V. Thacker (1350072)
- Murugappan Muthukumar (1334703)
- Ulrich F. Keyser (131654)
DOIAbstract
We report observations of a striking reversal in the direction of electroosmotic flow (EOF) outside a conical glass nanopore as a function of salt concentration. At high ionic strengths (>100 mM), we observe EOF in the expected direction as predicted by classical electrokinetic theory, while at low salt concentrations (<1 mM) the direction of the flow is reversed. The critical crossover salt concentration depends on the pore diameter. Finite-element simulations indicate a competition between the EOF generated from the inner and outer walls of the pore, which drives flows in opposite directions. We have developed a simple analytical model which reveals that, as the salt concentration is reduced, the flow rates inside the pore are geometrical...
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