Submerged micro-strucutures generate a soft boundary effect on active nematic flows

Actively driven bundled microtubule networks have become a useful framework to study energy driven defects in structured fluids. Moreover, the implementation of soft boundaries instead of hard side walls can be a useful strategy to control defect flow and dynamics. We study the behavior of an active nematic microtubule system confined by submerged complex geometries. From our preliminary work, we have observed that submerged 3D structures can influence defect dynamics. We also demonstrate that the soft barrier generated by the submerged structures form stagnation points near the boundary reminiscent of those seen for hard boundaries. With the assistance of micro fabrication, we investigate the spontaneous flows of this novel system under confined conditions i.e. in proximity to the boundary of the submerged structures. For this investigation, we used cylindrical pillars and rectangular trenches. We are also interested to learn if the submerged surfaces will impact chaotic mixing dynamics.