Chapter 8: Soft, Hard, and Hybrid Janus Structures: Synthesis, Self-Assembly, and Applications — Catalytic Janus Swimmers

This chapter describes how small-scale devices with a “two-faced” structure, often termed catalytic Janus swimmers, can be used to generate autonomous motion within fluids at small scales. The chapter starts by giving a general introduction to the field of swimming devices, and then surveys the variety of different Janus structures that have been used to produce motion. We then describe the methods that have been employed to synthesize these asymmetrical catalytic swimmers, and review the current understanding of the mechanisms that produce motion from catalytic Janus structures. The remainder of the chapter first focuses on the challenge of accurately quantifying the motion characteristics for catalytic Janus swimmers, and then describes the considerable challenge of controlling the directionality of motion, which is subject to stochastic phenomena. Finally, we survey existing demonstrations of potential applications for Janus catalytic swimmers, and discuss future directions within this research field.