Hauptseminar Active Matter SS 2017/Synthetic Microswimmers

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Date

2017-04-26

Time

17:30

Topic

Synthetic Microswimmers

Speaker

Carolin Dietrich

Tutor

Clemens Bechinger

Handout

[1]

Contents

The first attempts at creating such particles by the group of Prof. J. Bibette are considered to provide a background as 'mechanical' swimmers [1-2]. Synthetic microswimmers have recently stimulated considerable research interest from experimental and theoretical viewpoints. Self-phoretic effects have shown to be an effective and promising strategy to design such artificial microswimmers, where the microswimmers are driven by gradient fields locally produced by swimmers themselves in the surrounding solvent. Self-phoretic swimmers are typically composed of two parts: a functional part which modifies the surrounding solvent properties creating local gradient fields, and a non-functional part which is exposed then to the local field gradients [3-4]. Most existing experimental investigations of the self-phoretic microswimmers consider Janus particles, which can be quite easily synthesized using partial metal coating on colloidal spheres. In diffusio-phoretic microswimmers, the metal coated part catalyzes a chemical reaction to induce a concentration gradient [5-6]. When such particles are suspended in a binary mixture with a lower critical point and illuminated with light, the fluid locally demixes, which causes a self-diffusiophoretic motion [7]. In thermophoretic microswimmers, the metal coated part is able to effectively absorb heat from e.g. an external laser, which creates a local temperature gradient [8].

Literature

1. D. Dreyfus et al., Nature 437, 862 (2005)
2. P. Tierno et al., J. Phys. Chem. B 112, 16525 (2008)
3. J. Anderson, Annu. Rev. Fluid Mech. 21, 61 (1989)
4. J.F. Brady, J. Fluid Mech. 667, 216 (2011)
5. J. R. Howse, R. A. L. Jones, A. J. Ryan, T. Gough, R. Vafabakhsh, and R. Golestanian, Phys. Rev. Lett. 99, 048102 (2007).
6. J. Palacci, C. Cottin-Bizonne, C. Ybert, and L. Bocquet, Phys. Rev. Lett. 105, 088304 (2010).
7. I. Buttinoni, G. Volpe, F. Kümmel, G. Volpe, and C. Bechinger, J. Phys. Condens. Matter 24, 284129 (2012).
8. H.-R. Jiang, N. Yoshinaga, and M. Sano, Phys. Rev. Lett.105, 268302 (2010).