Ions in an AC Electric Field: Strong Long-Range Repulsion between Oppositely Charged Surfaces

Łukasz Richter, Paweł J. Żuk, Piotr Szymczak, Jan Paczesny, Krzysztof M. Bąk, Tomasz Szymborski, Piotr Garstecki, Howard A. Stone, Robert Hołyst, and Carlos Drummond
Phys. Rev. Lett. 125, 056001 – Published 28 July 2020
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Abstract

Two oppositely charged surfaces separated by a dielectric medium attract each other. In contrast we observe a strong repulsion between two plates of a capacitor that is filled with an aqueous electrolyte upon application of an alternating potential difference between the plates. This long-range force increases with the ratio of diffusion coefficients of the ions in the medium and reaches a steady state after a few minutes, which is much larger than the millisecond timescale of diffusion across the narrow gap. The repulsive force, an order of magnitude stronger than the electrostatic attraction observed in the same setup in air, results from the increase in osmotic pressure as a consequence of the field-induced excess of cations and anions due to lateral transport from adjacent reservoirs.

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  • Received 12 December 2019
  • Accepted 25 June 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.056001

© 2020 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft Matter

Authors & Affiliations

Łukasz Richter1, Paweł J. Żuk2,3, Piotr Szymczak4, Jan Paczesny1, Krzysztof M. Bąk5, Tomasz Szymborski1, Piotr Garstecki1, Howard A. Stone2, Robert Hołyst1,*, and Carlos Drummond6,7,†

  • 1Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw 01-224, Poland
  • 2Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
  • 3Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5b, Warsaw 02-106, Poland
  • 4Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, Warsaw 02-093, Poland
  • 5Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
  • 6CNRS, Centre de Recherche Paul Pascal (CRPP), UPR 8641, Pessac F-33600, France
  • 7Université de Bordeaux, CRPP, UPR 8641, Pessac F-33600, France

  • *rholyst@ichf.edu.pl.
  • drummond@crpp-bordeaux.cnrs.fr.

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Issue

Vol. 125, Iss. 5 — 31 July 2020

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