Using epoxy-based lithography to probe confinement effects on active nematics

Active nematics are out-of-equilibrium liquid crystal fluids composed of rod-like subunits, which can generate large-scale, self-driven flows. In this emerging field of active nematics, new methods are needed to investigate and potentially control phase structure and dynamics. The use of complex engineered surfaces using microfabrication is an excellent way to control local orientation directors, taking advantage of the interplay between surface curvatures and topological defects. Epoxy-based lithography represents a simple and appealing approach, using low cost, minimal materials and a time efficient process. In this manuscript, we discuss methods for optimized fabrication protocols using negative and positive tone epoxy-based photoresists to create microfluidic devices for active matter. Arrays of curved objects and submerged topographies can be used to generate a variety of liquid crystal defect configurations not typically observed on unconfined planar surfaces.