Polarity and chirality control of an active fluid by passive nematic defects

Alfredo Sciortino, Lukas J. Neumann, Timo Krüger, Ivan Maryshev, Tetsuhiko F. Teshima, Bernhard Wolfrum, Erwin Frey, Andreas R. Bausch

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Much like passive materials, active systems can be affected by the presence of imperfections in their microscopic order, called defects, that influence macroscopic properties. This suggests the possibility to steer collective patterns by introducing and controlling defects in an active system. Here we show that a self-assembled, passive nematic is ideally suited to control the pattern formation process of an active fluid. To this end, we force microtubules to glide inside a passive nematic material made from actin filaments. The actin nematic features self-assembled half-integer defects that steer the active microtubules and lead to the formation of macroscopic polar patterns. Moreover, by confining the nematic in circular geometries, chiral loops form. We find that the exact positioning of nematic defects in the passive material deterministically controls the formation and the polarity of the active flow, opening the possibility of efficiently shaping an active material using passive defects.

Original languageEnglish
Pages (from-to)260-268
Number of pages9
JournalNature Materials
Volume22
Issue number2
DOIs
StatePublished - Feb 2023

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