SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 38: Microswimmers and Fluid Physics of Life (joint session DY/CPP)

CPP 38.11: Talk

Wednesday, March 29, 2023, 17:45–18:00, MOL 213

New insights into the mechanism of self-phoresis — •Alvaro Domínguez¹, Mihail Popescu¹, and Siegfried Dietrich² — ¹Univ. Sevilla, Spain — ²MPI für Intelligente Systeme, Stuttgart

Chemophoresis describes the displacement of a particle in an ambient fluid due to a gradient in chemical composition. Classic phoresis can be understood through linear–response theory: in the presence of a sufficiently small gradient (∇ n)_ext in concentration, the phoretic velocity of the particle is V = L_lin(∇ n)_ext, in terms of the phoretic coefficient L_lin given by a Green–Kubo expression.

Self-phoretic particles induce a composition gradient (∇ n)_act through catalytic activity and provide a physical realization of artificial swimmers. Experimental observations are then customarily addressed as another instance of classic phoresis, V = L_lin(∇ n)_act.

However, an additional role of the particle’s chemical activity has been recently identified [1,2], namely, as responsible for a specific activity–induced response L_act, so that one has to write

in the more general scenario. This would mean a change in paradigm as it disproves the claim that “self-phoresis is phoresis in a self-induced gradient”.