Colloidal Motility and Pattern Formation under Rectified Diffusiophoresis

Jérémie Palacci (1) , Benjamin Abécassis (2) , Cécile Cottin-Bizonne (1) , Christophe Ybert (1) , Lydéric Bocquet (1)

1 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
2 LPS - Laboratoire de Physique des Solides

In this Letter, we characterize experimentally the diffusiophoretic motion of colloids and-DNA toward higher concentration of solutes, using microfluidic technology to build spatially and temporally controlled concentration gradients. We then demonstrate that segregation and spatial patterning of the particles can be achieved from temporal variations of the solute concentration profile. This segregation takes the form of a strong trapping potential, stemming from an osmotically induced rectification mechanism of the solute time-dependent variations. Depending on the spatial and temporal symmetry of the solute signal, localization patterns with various shapes can be achieved. These results highlight the role of solute contrasts in out-of-equilibrium processes occurring in soft matter.

Domaines: Matière Condensée [cond-mat]

Jérémie Palacci, Benjamin Abécassis, Cécile Cottin-Bizonne, Christophe Ybert, Lydéric Bocquet. Colloidal Motility and Pattern Formation under Rectified Diffusiophoresis. Physical Review Letters, 2010, 104 (13), ⟨10.1103/PhysRevLett.104.138302⟩. ⟨hal-01628772⟩