Shear-induced diffusion of plate-like 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 plate-like clay particles show a strong cross-stream shear-induced diffusivity at low volume fraction ($\phi_0 \leq 0.01$). Moreover, we find a linear dependence of the collective diffusion coefficient with the average shear rate (in the range $10^2$--$10^4$~$\mathrm{s}^{-1}$) 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.