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.

Formation of self-propelling clusters starting from randomly dispersed Brownian particles

“…Self-assembly of the active matter giving rise to complex architecture like living clusters due to symmetry breaking has been widely observed [10,[33][34][35]. The phoretic interaction followed by short-range van der Waals and critical Casimir attractions are argued to be responsible for such clustering in case of the active particles [10,33].…”

Barrier-mediated predator-prey dynamics

“…Recently there has been a lot of activity in unanimate predator-prey systems designed by using synthetic colloidal particles which interact in a non-reciprocal way. Different realizations involve ion exchange resins building so-called "modular microswimmers" [19][20][21][22][23], moving droplets following each other [1,24], predator-prey-like entities for active colloidal molecules [25][26][27][28][29], pairs of dust particles in a complex plasma [30,31], and biomimetic active micromotor systems [32]. Even details of the particle perception can be programmed in synthetic colloidal model systems [33,34].…”