SKM 2023 – wissenschaftliches Programm

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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: Vortrag

Mittwoch, 29. März 2023, 17:45–18:00, MOL 213

New insights into the mechanism of self-phoresis — •Alvaro Domínguez1, Mihail Popescu1, and Siegfried Dietrich21Univ. 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 = Llin(∇ n)ext, in terms of the phoretic coefficient Llin 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 = Llin(∇ 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 Lact, so that one has to write

V =
Llin + Lact

(∇ n)ext + (∇ n)act 

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”.

[1] A. Domínguez, M. Popescu, C. Rohwer, S. Dietrich, Physical
 Review Letters, 125, 268002 (2020).
[2] A. Domínguez, M. Popescu, Current Opinion in Colloid
 & Interface Science, 61, 101610 (2022).
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