Mechanisms of Symmetry Breaking in a Multidimensional Flashing Particle Ratchet

Ofer Kedem, Bryan Lau, Emily A. Weiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Ratcheting is a mechanism that produces directional transport of particles by rectifying nondirectional energy using local asymmetries rather than a net bias in the direction of transport. In a flashing ratchet, an oscillating force (here, an AC field) is applied perpendicular to the direction of transport. In an effort to explore the properties of current experimentally realizable ratchet systems, and to design new ones, this paper describes classical simulations of a damped flashing ratchet that transports charged nanoparticles within a transport layer of finite, non-zero thickness. The thickness of the layer, and the decay of the applied field in the z-direction throughout that thickness, provide a mechanism of symmetry breaking in the system that allows the ratchet to produce directional transport using a temporally unbiased oscillation of the AC driving field, a sine wave. Sine waves are conveniently produced experimentally or harvested from natural sources but cannot produce transport in a 1D or pseudo-1D system. The sine wave drive produces transport velocities an order of magnitude higher than those produced by the common on/off drive, but lower than those produced by a temporally biased square wave drive (unequal durations of the positive and negative states). The dependence of the particle velocity on the thickness of the transport layer, and on the homogeneity of the oscillating field within the layer, is presented for all three driving schemes.

Original languageEnglish (US)
Pages (from-to)7148-7155
Number of pages8
JournalACS nano
Issue number7
StatePublished - Jul 25 2017


  • Brownian motor
  • broken symmetry
  • finite element
  • flashing ratchet
  • nonequilibrium
  • particle ratchet
  • simulation

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)
  • Materials Science(all)


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