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Tractionless Self-Propulsion of Active Drops

Research output: Contribution to journalArticle

Original languageEnglish
Article number248006 (2019)
Number of pages6
JournalPhysical Review Letters
DateAccepted/In press - 20 Nov 2019
DatePublished (current) - 13 Dec 2019


We report on a new mode of self-propulsion exhibited by compact drops of active liquids on a substrate which, remarkably, is tractionless, i.e., which imparts no mechanical stress locally on the surface. We show, both analytically and by numerical simulation, that the equations of motion for an active nematic drop possess a simple self-propelling solution, with no traction on the solid surface and in which the direction of motion is controlled by the winding of the nematic director field across the drop height. The physics underlying this mode of motion has the same origins as that giving rise to the zero viscosity observed in bacterial suspensions. This topologically protected tractionless self-propusion provides a robust physical mechanism for efficient cell migration in crowded environments like tissues.

    Research areas

  • Synthetic Biology

    Structured keywords

  • BrisSynBio
  • Bristol BioDesign Institute

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