Morphing Colloidal Crystals with Active Additives

Active matter studies have focused mostly on homogenous systems where all elements are active. However, for dense systems the forces applied by small quantities of active matter can have far-reaching effects. Because the positions of particles in colloidal crystals are highly correlated, an active particle’s sphere of influence in such a medium can extend many particle diameters away. By controlling the creation and propagation of mobile defect species this range can be further extended. In this work we discuss how small clusters of active particles with variable diameter can cause long range shear displacement within a simulated colloidal monolayer. Such displacement can be confined to a single slip plane by the design of the embedded cluster. We approach the design of these heterogeneous active materials by focusing on the creation and migration of dislocation defects from the embedded cluster edges during expansion. We demonstrate the reconfiguration of large quantities of passive colloidal crystal with a small amount of active matter. Using a designed cluster shape with a single cyclic actuation mode, large plastic deformations can be accomplished over the course of many swell/shrink cycles, providing a new way of creating morphing matter for soft colloidal robotics.