Light-activated kinesin tune defect density and nematic speed

Active nematics are intrinsically unstable and unconfined active nematics generate turbulent flows. To control the flow and suppress turbulence we developed a 2D active nematic system consisting of microtubule bundles driven by light-activated kinesin motor clusters. Here, we investigate how the intensity of uniformly applied light affects active nematic properties. We use particle image velocimetry to calculate the nematic speed and the nematic director field to extract spatial and temporal nematic characteristics, such as the defect density. We find that at low light intensities, the nematic speed and the defect density are proportional to the intensity of light. This system has the potential to be combined with control theory protocols to create designed spatiotemporal flows.