Two step micro-rheological behavior in a viscoelastic fluid

We perform micro-rheological experiments with a colloidal bead driven through viscoelastic worm-like micellar fluid and observe two distinctive shear thinning regimes, each of them displaying Newtonian-like plateau. The behavior at larger velocities is in qualitative agreement macroscopic rheological experiments. second process, observed Weissenberg numbers as small few percent, appears to have no analog macro-rheological findings. A simple model introduced earlier captured the implied that processes correspond different length scales fluid. This also reproduces oscillations, which been this system previously. While under macro-shear seems be near equilibrium for rates regime intermediate plateau, one micro-shear thus still far from it. analysis suggests existence scale micrometres, nature remains elusive.