Funnel ratchets in biology at low Reynolds number: Choanotaxis

Peter Galajda, Juan Keymer, Joanna Dalland, Sungsu Park, Songzi Kou, Robert Austin

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


We present an example of a ratchet phenomena in biology consisting of swimming bacteria in an enclosed structure separated by a wall of funnels. The funnels serve to concentrate bacteria that are motile, in spite of the fact that the motion occurs at low Reynolds numbers and would be expected to be time reversible invariant. We discuss some of the basic ideas which underly the phenomena including spatial and temporal coherence of the motion of bacteria and interaction of the bacteria with surfaces.

Original languageEnglish (US)
Pages (from-to)3413-3422
Number of pages10
JournalJournal of Modern Optics
Issue number19-20
StatePublished - Nov 2008

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


  • Bacteria
  • Biology
  • Low Reynolds number
  • Phase space
  • Ratchet
  • Reversible
  • Time dependence


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