Design of active nematic systems with controllable defect dynamics and flows

Active matter encompasses a wide spectrum of non-equilibrium condensed matter systems, the constituents of which convert energy into mechanical work. They exhibit intriguing collective behaviors, such as flocking and activity-induced phase transitions. In the particular case of anisotropic particles or molecules, these materials can enter an active nematic state, which displays intricate motions of topological defects, characteristic of nematic liquid crystals, accompanied by chaotic-like flows. Active nematics are encountered in numerous biological systems, ranging from cytoskeletal polymer extracts, to tissue cells and dense bacterial suspensions. The dynamics of active nematics are not fully understood, and efforts to control and manipulate the structure and flow of this class of materials have been limited. In this talk, I will summarize our recent progress in active nematics research, with an emphasis on the interplay between molecular interactions, elasticity, and hydrodynamic forces. In particular, I will discuss an experimentally realizable approach, which relies on spatiotemporal patterning of activity, to manipulate defects and flows in active nematics. I will show how simulations can be harnessed to guide design of well-controlled dynamics, paving the way towards engineering active matter for practical applications.