Abstract
We investigate experimentally the electrokinetic properties of soft nanofluidic channels that consist in soap films with nanometric thickness, covered with charged surfactants. Both the electric and fluidic responses of the system are measured under an applied voltage drop along the film. The electric field is shown to induce an electro-osmotic hydrodynamic flow in the film. However, in contrast to systems confined between solid surfaces, the soft nature of the nanochannel results furthermore in a thickening of the film. This effect accordingly increases the total electro-osmotic flow rate, which behaves nonlinearly with the applied electric field. This behavior is rationalized in terms of an analogy with a Landau-Levich film withdrawn from a reservoir, with the driving velocity identified here with the electro-osmotic one.
- Received 30 October 2012
DOI:https://doi.org/10.1103/PhysRevLett.110.054502
© 2013 American Physical Society
Focus
Tuning the Flow through a Soap Film
Published 1 February 2013
An electric field applied to a soap film induces fluid flow through the film and causes its thickness to increase—a phenomenon that could be useful in microfluidic systems.
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