Reconfigurable Hierarchical Colloidal Assembly on Programmable Energy Landscapes.

We develop an approach in computer simulations to control reconfigurable hierarchical colloidal assembly on programmable energy landscapes, which are mediated by colloidal interactions in electric fields. An addressable electrode array is implemented to shape nonuniform interfacial electric fields that mediate particle dipolar interactions, local concentration and microstructure, and dielectrophoretic/electrophoretic transport. A specific target structure is initially investigated, which consists of periodic patterns of circular-shaped colloidal crystals with length scales corresponding to pattern periodicity, local crystal morphology, and crystalline microstructure. Serial and parallel steps are designed and optimized to perform several key steps, including patterning coarse concentration profiles, refining high-fidelity features based on particle numbers within local features, repairing local crystal defects, and final sculpting of local pattern morphological features. The approach is demonstrated in more diverse examples including different pattern sizes, types, particle shapes, and microstructures with different levels of positional and orientational order and disorder. Findings from this work can be generalized to any interaction that mediates reconfigurable energy landscapes, which provides a basis for fabrication of hierarchical materials with exotic emergent and multifunctional properties as well as functional devices and microscopic machines.