NSF-supported research at the Advanced Materials and Liquid Crystal Institute: Liquid crystals command swimming bacteria
Transport of fluids and particles at the micro scale is an important theme both in fundamental and applied science. The project explores how this transport can be controlled by anisotropic fluids, namely, by a liquid crustal with pre-designed spatially-variable orientation of molecules. The main focus is dynamic artificial colloidal particles powered by an external electric field. Over the last year, the project extended to "living colloids", i.e., self-propelling rod-like bacteria swimming in a patterned liquid crystal. The experiments revealed an extraordinary efficiency of the patterned liquid crystal in control of bacterial trajectories and concentration. Bacteria recognize subtle differences in liquid crystal environment, engaging in bipolar swimming in regions of pure bend or splay but switching to unipolar swimming in mixed splay-bend regions, as shown in Figure. Sensitivity of bacteria to pre-imposed orientational patterns represents a new facet of the interplay between hydrodynamics and topology of active matter.
References: C. Pend et al, Science 354, 882 (2016),