Guest Seminar - Active Liquid Crystals from Engineered Biopolymers

Active matter encompasses a wide spectrum of non-equilibrium systems, the constituents of which can convert energy into local mechanical work, giving rise to long-range collective dynamics. Examples include bird flocking, fish schooling and cytoplasmic streaming. A paradigmatic active matter system is active nematic liquid crystals (LCs), which consist of anisotropic units that can form a nematic phase. The self-propulsion of these units leads to large-scale spontaneous flows, nucleation and autonomous motion of topological defects, which may find applications in microfluidics and photonics. However, control of the dynamics of active topological defects is notoriously difficult, limiting their further applications.
In this talk, I will introduce biopolymer-based active nematics. Specifically, I will discuss how actin filaments and myosin motors can be used to construct an active nematic in which theoretical results from active LCs are successfully confirmed. We further show how an engineered myosin can be used to realize a spatially patterned active LCs, through which a combination of simulation and experiment demonstrate a high degree of control over the nucleation and trajectory of topological defects. We further propose an active LC-based microfluidic device in which these active topological defects can perform logic operations. Taken together, our research demonstrates the ability to control the structure and dynamics of topological defects in biological materials, and paves the way towards the design of autonomous materials.