Non-equilibrium colloidal topological soft matter

Non-equilibrium soft matter is today an active research area in physics and multidisciplinary natural sciences. Active and driven agents – both biological and engineered – are at the core of active matter, exhibiting locomotion, rotation, and general motility at the expense of using external energy provided by the environment, either via chemical energy, material flow or external fields. At the focus of new non-equilibrium material development is being able to design, control and manipulate the dynamics, interaction, and assembly of driven active agents. In this project, we want to develop and explore novel non-equilibrium colloidal materials by exposing them to anisotropic environment of complex nematic fluids in a microfluidic set-up. Such colloidal materials generate topological defect lines that are driven out of equilibrium by microfluidic flow and external fields. Topological defects are omnipresent in non-equilibrium nematic fluids and in three dimensions generally appear as defect lines, also called disclinations. Recently, advances have been made on the theoretical understanding of disclination dynamics, interaction, and characterization, as well as experimental breakthroughs on generating active disclinations and controlling disclination dynamics and stability out of equilibrium. Building on these advances, we propose a new methodological approach that is based on simulating disclinations as elastic-like objects with distinct dynamics, interactions, and cross-over events. We will combine the developed methodological approach and advanced experiments on disclination line dynamics around colloidal particles fixed in microfluidic channels. Using novel micro-fabrication techniques for printing colloidal microparticles with complex shapes (customizing the edge profiles, genus of particles, linked particles) and microfluidic confinement, we will generate disclination lines with different topological and structural properties and deform them far from equilibrium using microfluidic flows and electric fields. The numerical model will be used to determine the main mechanisms of defect line dynamics and we will design the necessary control mechanisms for steering, propulsion, and interaction of colloidal particles. We will make suspensions of multiple colloidal particles, where microfluidic flow will generate highly distorted defect lines, which will aid the interaction and assembly into colloidal crystals and amorphous matter. The distinctly non-equilibrium nature of such structure will lead to constantly rewiring defect line networks and particle positions, with soft response to external fields and self-healing properties. Finally, the project is aimed at developing a novel non-equilibrium responsive colloidal matter with novel mechanisms of structure assembly, self-healing, and control.