External perturbations affect the strength of the critical Casimir force, the time-dependence of which displays interesting features

Steering the critical Casimir effect: lateral forces, levitation, and dynamics

Andrea Gambassi

SISSA – International School for Advanced Studies and INFN, via Bonomea 265, 34136 Trieste (Italy), E–mail: gambassi@sissa.it

The critical Casimir effect results from the confinement of the pro- nounced thermal fluctuations occurring upon approaching a second-order phase transition such as the demixing of a binary liquid mixture. The spatial direction of the force acting on the confining surfaces can be con- trolled by suitably patterning these surfaces. For a colloid close to a pat- terned substrate and immersed in a critical solvent a spatially confining potential can be reversibly generated, which also allows a temperature- controlled stable levitation of the particle. External perturbations affect the strength of the critical Casimir force, the time-dependence of which displays interesting features.

I will present recent results of the theoretical investigation of these various aspects, comparing them with the available experimental data.

[1] M.Troendle, S.Kondrat, A.Gambassi, L.Harnau, and S.Dietrich, EPL88(2009) 40004

[2] A.Gambassi and S.Dietrich,Soft Matter7, 1247 (2011)

[3] M.Troendle, O.Zvyagolskaya, A.Gambassi, D.Vogt, L.Harnau, C.Bechinger, and S.Dietrich,arXiv:1012.0181

[4] A.Gambassi,Eur. Phys. J. B64, 379 (2008)

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