Functionalization of boundaries in active nematics: inclusions and confinement.
Active fluids and their spontaneous flows promise exciting new paths toward efficient transport phenomena and new autonomous materials. However, the fulfillment of this promise pends on finding effective ways to control them. In this regard, an auspicious avenue is the use of inclusions and confinement, which, in its simplest form, has led to the emergence of long-lived coordinated flows. Here we extend these efforts in two different ways: First, we show how combining custom anchoring conditions within nematic colloidal inclusions can lead to an effective self-propulsion. In particular, we show how the steering dynamics of such self-propulsion is intimately linked to the dynamics of a companion -1/2 topological defect. Second, by expanding to 3D channels, we show how confinement can lead to spontaneous helical flows that break chiral symmetry both locally and globally. As such, this work demonstrates the potential of confinement geometry to unravel complex but organized spatiotemporal structures in active liquid crystals, thus showing that they may present a path to functionality.
