Directed assembly of active colloidal molecules

Abstract

Having a production line for microrobots is fundamental to their widespread application in many areas. Thanks to their flexibility, active colloidal molecules with dynamic function are a promising model for microrobots. So far, the production of colloidal molecules requires a great deal of engineering and ad hoc processes. Here, we first describe a method for the continuous production of dimers and trimers formed by non-polar spherical active colloidal particles. We use external fields to both guide the monomers and rotate the colloidal molecules as to obtain dimers and trimers with very high yield and highly localized in space. We also show how fields and rigid walls can be used to direct small colloidal molecules to specific locations. Finally, we study the possible colloidal molecules that can be created with these building blocks and propose a general mechanism for the directed assembly of colloidal molecules with dynamic function.