Nematic textures in microfluidic environment

We study the flow of a nematic liquid crystal through microchannels possessing degenerate planar anchoring conditions on the channel walls. Depending on the channel dimensions and the flow rate, the formation of different textures and topological defect structures is observed and studied using polarizing optical microscopy and fluorescence confocal polarizing microscopy. The observed structures comprise π-walls, disclination lines pinned to the channel walls, disclination lines with one pinned and one freely suspended end, and disclination loops freely flowing in a chaotic manner. We focus on the creation, evolution and morphology of different kinds of π-walls and pinned disclinations. Such defects and textures in the nematic fluid can potentially be applied for guiding the transport of individual particles and larger colloidal assemblies inside an appropriate microfluidic device.