Self-motility of an active particle induced by correlations in the surrounding solution

TL;DR

This paper proposes a new theoretical mechanism for active particle self-motility driven by correlations in the surrounding solution, independent of traditional molecular force models, with potential velocities reaching micrometers per second.

Contribution

It introduces a novel self-motility mechanism based on correlation-induced diffuse interfaces, expanding understanding beyond molecular force-based phoretic models.

Findings

Velocity can reach micrometers per second.

Velocity depends bilinearly on activity.

Double velocity reversal possible with changing correlation length.

Abstract

Current models of phoretic transport rely on molecular forces creating a "diffuse" particle-fluid interface. We investigate theoretically an alternative mechanism, in which a diffuse interface emerges solely due to a non-vanishing correlation length of the surrounding solution. This mechanism can drive self-motility of a chemically active particle. Numerical estimates indicate that the velocity can reach micrometers per second. The predicted phenomenology includes a bilinear dependence of the velocity on the activity and a possible double velocity reversal upon varying the correlation length.