title: Command of active matter by topological defects and patterns.
abstract: Self-propelled bacteria are marvels of nature with a potential to power dynamic materials and microsystems of the future. The challenge lies in commanding their chaotic behavior. By dispersing swimming Bacillus subtilis in a liquid crystalline environment with spatially varying orientation of the anisotropy axis, we demonstrate control over the distribution of bacterial concentration, as well as the geometry and polarity of their trajectories. Bacteria recognize subtle differences in liquid crystal deformations, engaging in bipolar swimming in regions of pure splay and bend but switching to unipolar swimming in mixed splay-bend regions. They differentiate topological defects, heading toward defects of positive topological charge and avoiding negative charges. Sensitivity of bacteria to preimposed orientational patterns represents a previously unknown facet of the interplay between hydrodynamics and topology of active matter.
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA.
authors.forename: Chenhui
authors.initials: C
authors.lastname: Peng
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA.
authors.forename: Taras
authors.initials: T
authors.lastname: Turiv
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA.
authors.forename: Yubing
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA.
authors.forename: Qi-Huo
authors.initials: QH
authors.lastname: Wei
authors.affiliation: Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA. olavrent@kent.edu.
authors.forename: Oleg D
authors.initials: OD
authors.lastname: Lavrentovich
mesh_terms: D016880:Anisotropy; D001412:Bacillus subtilis / Q000502:physiology*; D057446:Hydrodynamics; D050866:Liquid Crystals; D008124:Locomotion; D008859:Microscopy, Polarization