Colloidal Micromachines Regulated by Liquid Crystals*

Reconfigurable microdevices have become a subject of intense interest due to their ability to harvest energy and change shape on demand. These attributes allow them to be used as robotic structures, constituents for self-healing materials, and switchable metamaterials. Yet, many of these structures are limited in utility by lack of control over their dynamics. Accordingly, much work has been done to engineer their shape, composition, and actuation as a means to control dynamics; however, little is known about regulation of their dynamics in complex fluid milieu. Here, we show how actuation of microdevices made from the assembly of patchy magnetic microcubes, which we refer to as “microbots”, can be regulated by the anisotropic viscoelastic environment of a liquid crystal (LC). We show that the elastic energy arising from the strain of LC around microbots directly influences their folding dynamics, which can be tuned by tailoring: (i) the far-field orientation of the LC and (ii) the local ordering of the LC at the microbot surfaces. These findings represent a first step towards establishing a general set of design rules to control the dynamics of actuating devices via use of anisotropic fluids.