Towards a Colloidal Crystal Robot Gripper

Colloidal particles can be manufactured with varying shape, activity, or interaction patchiness to assemble into a wide variety of crystals. Converting a passive colloidal crystal into a crystalline colloidal robot that changes morphology and performs robotic tasks requires a blueprint to coordinate particle motion within a crystal. Such a machine could unlock new possibilities for manipulating microscale objects but requires a way to move matter in dense systems. Building on the work of VanSaders et. al., we study a strategy to control the formation and migration of dislocations, which carry plastic deformation in crystals, by implanting a cluster of cyclically swelling and deswelling colloids into a finite 2D colloidal crystallite. Across dozens of swelling cycles, the sequential motion of dislocations gradually changes the crystallite’s shape. In this computational project, we decompose the geometry of the cluster of swelling particles into basic elements such as angle, edge length and cluster asymmetry. We show how these geometric elements control where dislocations form and how they move in the 2D crystallite. As one example, we show how these design rules can be combined to create a colloidal robotic gripper to trap an object.