Negative mobility and sorting of colloidal particles

Eichhorn R, Regtmeier J, Anselmetti D, Reimann P. Negative mobility and sorting of colloidal particles. Soft Matter. 2010;6(9):1858-1862.Transport in the realm of soft matter is strongly influenced by diffusion. Conditions far from thermal equilibrium and non-linear dynamics may give rise to unexpected transport phenomena, which are ruled out by the second law of thermodynamics under equilibrium conditions. Here, we highlight one of them, namely the migration of colloidal microparticles opposite to a static force and illustrate its application for particle sorting purposes