Janus droplet as a catalytic micromotor

TL;DR

This paper presents a theoretical study of Janus droplets acting as catalytic micromotors, demonstrating high self-propulsion speeds and advantages like simple manufacturing and scalable size, with no stability threshold.

Contribution

It introduces a new model of Janus droplet micromotors that are scalable and stable without a stability threshold, unlike single-fluid droplets.

Findings

Self-propulsion speed exceeds 60 μm/s.

Janus droplets have no stability threshold, allowing size scaling.

Advantages include simple manufacturing and neutral buoyancy.

Abstract

Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, $60\; {\rm \mu m/s}$ and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers. The paper was finalized and submitted by Denis S. Goldobin after Sergey Sklyaev had sadly passed away on June 2, 2014.