Abstract
The authors introduce a method to control swimming bacteria by a liquid crystal environment. The paper shows that a liquid crystal nematic patterned as a spiral vortex causes an individual-to-collective transition as the bacterial concentration increases, in which non-polar swimming of individual bacteria is replaced by a unipolar circular swirling of condensed swarms.
Highlights
Aqueous dispersions of self-propelled microswimmers such as motile flagellated bacteria that convert stored energy into mechanical motion are one of the most studied examples of active matter [1]
Our work demonstrates that by replacing the isotropic environment with nematic vortices, which mediates the interactions of the hydrodynamic force dipoles through the underlying director, one can achieve a stable parallel polar swimming of bacteria with controllable scenarios, such as swirl expansion and swirl contraction
In addition to the overall concentration cv measured as a number of bacteria per unit volume, which does not depend on the particular director pattern, we introduce a local vortex-specific volume concentration cp measured by counting the bacteria within a box x× y×d centered at the vortex core, where x = y = 0.4 mm
Summary
Aqueous dispersions of self-propelled microswimmers such as motile flagellated bacteria that convert stored energy into mechanical motion are one of the most studied examples of active matter [1]. Recent reports demonstrate intriguing examples of collective effects at length scales much larger than the size of an individual swimmer, such as coordinated motion and self-concentration caused by hydrodynamic and steric interactions of bacteria among themselves and with bounding surfaces [2,3,4,5,6,7] These studies are of importance for the fundamental understanding of active matter [1,8] and for potential future applications, since the power of collective motion can be harnessed to drive micromachines [9,10,11].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
