Acoustically energized active nematic drops

Nematic droplets are regions of fluid where elongated molecules align parallel to each other, surrounded by an isotropic liquid. Their topological order in equilibrium is influenced by factors such as material properties, temperature, surface energy, and external conditions. In this study, we explore the non-equilibrium dynamics of nematic droplets made from a lyotropic chromonic liquid crystal energized by an acoustic wave. Our experiments reveal that a nematic tactoid - a spindle-shaped droplet - displays a variety of dynamic behaviors, including stretching along molecular orientations, bending, splitting, merging, locomotion, and directional rotation. Notably, a pulse of acoustic energy can induce a transformation from a tactoid to a higher-energy topological state, such as a torus. These results deepen our understanding of active liquid crystals in a biphasic state and provide valuable insights into the behavior of active nematic droplets.