  We present a comprehensive description of vector chromatography that includes
deterministic and stochastic transport in 1D-periodic free-energy landscapes,
with both energetic and entropic contributions, and highlights the parameters
governing the deflection angle, i.e. the Peclet number and the partition ratio.
We also investigate the dependence of the deflection angle on the shape of the
free-energy landscape by varying the width of the linear transitions in an
otherwise dichotomous potential. Finally, we present experimental results
obtained in a microfluidic system in which gravity drives the suspended
particles and, in combination with a bottom surface patterned with shallow
rectangular grooves, creates a periodic landscape of (potential) energy
barriers. The experiments validate the model and demonstrate that a simple,
passive microdevice can lead to vector separation of colloidal particles based
on both size and density.
