Convective Self-Sustained Motion in Mixtures of Chemically Active and Passive Particles

• Published in: Langmuir 2017-08, Vol.33 (32), p.7873-7880
• Main Authors: Shklyaev, Oleg E, Shum, Henry, Yashin, Victor V, Balazs, Anna C
• Format: Article
• Language: English
• Subjects: Chemistry; Materials Science
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.7b01840

We develop a model to describe the behavior of a system of active and passive particles in solution that can undergo spontaneous self-organization and self-sustained motion. The active particles are uniformly coated with a catalyst that decomposes the reagent in the surrounding fluid. The resulting variations in the fluid density give rise to a convective flow around the active particles. The generated fluid flow, in turn, drives the self-organization of both the active and passive particles into clusters that undergo self-sustained propulsion along the bottom wall of a microchamber. This propulsion continues until the reagents in the solution are consumed. Depending on the number of active and passive particles and the structure of the self-organized cluster, these assemblies can translate, spin, or remain stationary. We also illustrate a scenario in which the geometry of the container is harnessed to direct the motion of a self-organized, self-propelled cluster. The findings provide guidelines for creating autonomously moving active particles, or chemical “motors” that can transport passive cargo in microfluidic devices.