A theoretical analysis of the resolution due to diffusion and size dispersion of particles in deterministic lateral displacement devices

We present a model including diffusion and particle-size dispersion for the separation of particles in deterministic lateral displacement devices also known as bumper arrays. We determine the upper critical diameter for diffusion-dominated motion and the lower critical diameter for pure convection-induced displacement. Application of our model to data suggests that the systematic deviation, observed for small particles in several experiments, from the critical diameter for separation given by simple laminar flow considerations may be explained by diffusion and size dispersion.