Tunable long range forces mediated by self-propelled colloidal hard spheres

R. Ni*, M.A. Cohen Stuart, P.G. Bolhuis

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

115 Citations (Scopus)


Using Brownian dynamics simulations, we systematically study the effective interaction between two parallel hard walls in a 2D suspension of self-propelled (active) colloidal hard spheres, and we find that the effective force between two hard walls can be tuned from a long range repulsion into a long range attraction by changing the density of active particles. At relatively high densities, the active hard spheres can form a dynamic crystalline bridge, which induces a strong oscillating long range dynamic wetting repulsion between the walls. With decreasing density, the dynamic bridge gradually breaks, and an intriguing long range dynamic depletion attraction arises. A similar effect occurs in a quasi-2D suspension of self-propelled colloidal hard spheres by changing the height of the confinement. Our results open up new possibilities to manipulate the motion and assembly of microscopic objects by using active matter.
Original languageEnglish
Article number018302
Number of pages5
JournalPhysical Review Letters
Publication statusPublished - 2015


  • active brownian particles
  • phase-separation
  • swimmers
  • disks


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