An Optically Driven Bi-Stable Janus Rotor with Patterned Metal Coatings

Yiwu Zong, Jing Liu, Rui Liu, Honglian Guo, Mingcheng Yang, Zhiyuan Li, and Ke Chen

Bi-stable rotation is realized for a gold-coated Janus colloidal particle in an infrared optical trap. The metal coating on the Janus particles are patterned by sputtering gold on a monolayer of closely packed polystyrene particles. The Janus particle is observed to stably rotate in an optical trap. Both the direction and the rate of rotation can be experimentally controlled. Numerical calculations reveal that the bi-stable rotation is the result of spontaneous symmetry breaking induced by the uneven curvature of the coating patterns on the Janus sphere. Our results thus provide a simple method to construct large quantities of fully functional rotary motors for nano- or micro-devices.

DOI