Design of Defect Dynamics and Flows in Active Liquid Crystal Systems

Liquid crystals (LCs) represent a state of matter that are intermediate between simple liquids and crystalline solids. Its orientational ordering in the nematic phase gives rise to structural anisotropy, the ability to form topological defects, and extraordinary sensitivity to external stimuli, making it an attractive class of materials for applications including display and biosensing. Active LCs, which convert other forms of energy into motion, can therefore offer a new platform to study non-equilibrium matter and to design biomimetic applications. Examples of active LCs include bacteria-LC composites, certain tissues, and dense biopolymer suspensions. When driven internally or externally out of equilibrium, the induced defect dynamics and hydrodynamic flows in these systems are often-times difficult to control, limiting their further applications. In this talk, I will discuss several recent experimental and simulation efforts which demonstrate that nucleation and self-propulsion of defects can be manipulated through, for example, spatiotemporal patterning of activity. I demonstrate that hydrodynamic simulations are particularly successful in elucidating the regulated dynamics and flows observed in cytoskeletal polymer-based active LC experiments performed by our collaborators. I will further show how the highly controlled defect motion and spontaneous flows can be used to transmit force and even information, paving the way towards the design of LC-based autonomous materials systems.