Active nematic defect control via variations in oil sublayer thickness

Actively driven bundled microtubule networks are highly adaptive systems that are sensititve to changes to it’s microevironment. We study the behavior of a two-tier active nematic microtubule/kinesin system confined to elevated microfabricated pillars. Flow dynamics in these systems are influenced by a circular confining geometry where active material at the top of pillar is referred to as a “second tier” configuration. In this work, we develop a method to curve the surface of an isotropic oil layer via the wetting of cylindrical microfabricated pillars. Not unlike the active material confined by hard boundaries, the active nematic material in our elevated system exhibits similar defect dynamics where bundled microtubules braid and align at the boundary. The oil layer in the 2^nd tier region is thinner than outside the boundary and consequently, becomes an area of high friction. Within the pillar region, active length scales and velocities are reduced due to larger viscosity thus we aim to calculate defect distributions, densities and velocity fields.