Physics Virtual Colloquia: 3D Active Nematics

The Department of Physics welcomes Dr. Guillaume Duclos to present this week’s virtual colloquia. Dr. Duclos is a assistant professor of physics at Brandeis University. He holds a doctoral degree from the Institut Curie — University Pierre et Marie Curie, Paris, France in 2015.

Abstract: Active fluids are dense suspensions of self-propelled units that convert internal energy into mechanical forces. The continuous input of energy at the particle scale breaks time-reversal symmetry and liberates active fluids from the constraints of thermodynamic equilibrium. Biomimetic fluids have become a paradigm for investigating non-equilibrium dynamics in active matter. In this vein, Dr. Duclos will present some recent work on building active materials out of biological polymers and molecular motors. In particular, he will present some recent experimental work on the generic hydrodynamic instability that drives the nucleation of defects in a 3D active liquid crystal. He will show how the rheology of the material can be inferred from the directionality of the instability. Then, he will present how light-sheet microscopy can be employed to reveal the structure and the dynamics of topological defects in 3D. Point-like motile topological defects control the universal dynamics of diverse 2D active nematics ranging from shaken granular rods to cellular monolayers, but a comparable understanding in 3D has yet to emerge. Dr. Duclos will show that the primary topological excitations in 3D active nematics are topologically neutral disclination loops that undergo complex dynamics and recombination events. These works illustrate how biochemistry, soft matter physics, and microscopy can be leveraged to design novel materials endowed with properties usually found only in living systems.