Shear-induced diffusion of platelike particles in microchannels.

We exploit the recent developments of microfluidic technologies to investigate the collective shear-induced diffusion in suspensions of micron-sized particles. Whereas spherical particles do not diffuse on the time scale of our experiments, the results with platelike clay particles show a strong cross-stream shear-induced diffusivity at low volume fraction (phi{0}<or=0.01). Moreover, we find a linear dependence of the collective diffusion coefficient with the average shear rate (in the range 10;{2}-10;{4} s;{-1}) and the particle concentration. These data are in good agreement with previous experimental and theoretical results for spheres when rescaled with the particle number density.