(29h) Using Defects to Reshape Colloidal Assemblies

Directed assembly at the colloidal scale remains challenging despite advances in using optical forces to manipulate nanoparticles. Optical holography allows for precise positioning of components, but does not scale well to thousands or millions of particles. However in dense colloidal systems particle positions are highly correlated, and so not every particle need be controlled in order to enact reconfigurations of the dense assembly. In this work we use simulation to study how a small number of particles embedded within a colloidal monolayer can exert forces which lead to long range permanent deformation of the monolayer edges. By framing the problem in terms of the creation and migration of mobile dislocation defects, we uncover design principles for the embedded cluster shape which result in the accumulation of large shear deformations on lattice planes. We show that arbitrary control of shear deformation localized to a single plane is sufficient to carry out a variety of useful reshaping operations on crystalline colloidal monolayers. This work represents a method to increase the length scale of control achieved with optical forces without imposing additional complexity on the optical system required.