Dislocation machines: topological defects for organizing the reconfiguration of active crystalline m
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Bryan VanSaders (James Franck Institute, University of Chicago)
Abstract: Colloidal nanoparticles capable of exerting microscopic forces (known as active matter) suggest a future class of robotic swarm metamaterials with attractive life-like properties. These microscopic swarms must coordinate their actions to accomplish robotically useful tasks, such as changing the swarm shape or engulfing an object. Contrary to their macroscopic counterparts, microscopic swarms must achieve this coordination without complex inter-particle communication. Therefore, active matter for robotic applications requires emergent behaviors with a minimum of explicit computation, a form of physical intelligence derived from the interactions and dynamics of the swarm. Following this principle, we explore through computer simulation how cycles of local non-conservative interaction between constituents can control the dynamics of topological defects in 2D metamaterials. Such defects link microscopic and macroscopic system length scales, allowing for local work expenditure to drive system-wide mechanical reconfigurations. We explore two examples of local work cycles – controlled dislocation creation reactions through local bond stretching and self-propelled dislocations from local bond torsion. These examples highlight how emergent phenomena can organize local work dissipation for system-spanning reconfigurations.
Bio: Bryan VanSaders is currently a Kadanoff-Rice postdoctoral fellow at the University of Chicago, working with Professors Heinrich Jaeger and Vincenzo Vitelli. He earned his PhD in Materials Science and Engineering from the University of Michigan, working with Professor Sharon Glotzer. He uses computer simulation to study active soft matter systems, which present new possibilities for creating synthetic materials with life-like properties through the dissipation of work at the microscopic scale. He is particularly interested in the intersection of active matter and topological defects in dense crystalline colloidal assemblies, and the role of information in emergent swarm dynamics. He also studies nonequilibrium methods of driving soft material assembly through acoustic and electrical fields.