Tunable soft structure in charged fluids confined by dielectric interfaces

Jos W. Zwanikken, Monica Olvera De La Cruz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Fluids of charged particles act as the supportingmedium for chemical reactions and physical, dynamical, and biological processes. The local structure in an electrolytic background is deformed by micro- and nanoscopic polarizable objects. Vice versa, the forces between the objects are regulated by the cohesive properties of the background. We study here the range and strength of these forces and the microscopic origin from which they emerge.We find the forces to be sensitively dependent on thematerial properties of the charged fluid and the immersed solutes. The induced interactions can be varied over decades, offering high tunability and aided by accurate theory, control in experiments and applications. To distinguish correlational effects from simple ionic screening, we describe electrolyte-induced forces between neutral objects. The interplay of thermal motion, short-range repulsions, and electrostatic forces is responsible for a soft structure in the fluid. This structure changes near polarizable interfaces and causes diverse attractions between confining walls that seem well-exploited by microbiological systems. For parameters that correspond to monovalent electrolytes in biologically and technologically relevant aqueous environments, we find induced forces between nanoscopic areas of the order of piconewtons over a few nanometers.

Original languageEnglish (US)
Pages (from-to)5301-5308
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
StatePublished - Apr 2 2013


  • Molecular electronics
  • Multicomponent plasmas
  • Statistical thermodynamics
  • Surface structure

ASJC Scopus subject areas

  • General


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