Abstract

Man-made nano- and micro-motors are key to many future applications. I will describe highly reconfigurable self-assembly of colloidal micro-motors that exhibit a repetitive rotation when immersed in a liquid crystal and powered by a continuous exposure to unstructured ~1nW light. A monolayer of self-assembled azobenzene molecules defines how the liquid crystal’s optical axis mechanically couples to the colloidal particle’s surface, as well as how they jointly rotate as the light’s polarization changes. The rotating particle twists the liquid crystal, which, in turn changes polarization of the light traversing it. The resulting feedback mechanism spontaneously yields a continuous opto-mechanical cycle and drives the unidirectional particle spinning, with handedness and frequency robustly controlled by polarization and intensity of light. I will discuss how this may enable new forms of active matter and self-assembled machines.