Command of Swimming Bacteria by Liquid Crystals

Event Dates: 

Wednesday, February 28, 2018 - 4:00pm

CTQM Seminar Type: 

  • Related Seminar Series

Speaker Name(s): 

Oleg Lavrentovich

Speaker Affiliation(s): 

Kent State University

Abstract, Event Details: 

Self-propelled bacteria are marvels of nature. If we can control their dynamics, we could use it to power microsystems of the future. Unfortunately, bacteria swim mostly randomly in isotropic liquids such as water. It is difficult to control their dynamics by factors other than transient gradients of nutrients; visual, acoustic and tactile communication channels that humans use to control large animals are not effective. To establish communication, we replace water with a water-based lyotropic liquid crystal, which couples propulsion of bacteria to the orientational order of the medium. The long-range orientational order of the liquid crystal can be designed as uniform or be pre-patterned into various structures by a plasmonic photoalignment technique [1]. The preimposed patterns of liquid crystal orientation allow one to gain a significant control over the dynamics of bacteria, namely, their trajectories, polarity of swimming, spatial variation of concentration [2], and run-and-tumble behavior [3]. Topological defects of integer strength serve either as attractors or repellents of bacteria, while defect pairs and patterns with broken left-right symmetry pump the bacterial flows along a preselected polar axis. The study of bacteria-liquid crystal system might result in approaches to harness the energy of collective motion for micro-robotic, biomechanical, and sensing devices, as well as micro-mixing and transport of micro-cargo. The work is supported by NSF grants DMR-1507637 and DMS-1729509.