Directed self-assembly of dielectrically polydisperse nanoparticle suspensions into cohesive hierarchical patterns.

We show in this work that the inherent dielectric anisotropy of polydisperse suspensions consisting of positively and negatively polarizable nanoparticles can be exploited to guide their self-assembly into a range of hierarchically connected patterns by applying an external electric field. The assembly is driven by inter-particle forces which can be tailored by selecting suitable parameter values, such as the number and size ratios and the polarizabilities of positively and negatively polarizable particles, so that when the electric field is switched on the neighboring particles spontaneously rearrange relative to one another and come together to form cohesive patterns in which particles attract their nearest neighbors.