Fig. 2.

Shear profiles of bacterial suspensions. (A) Normalized shear profiles at different shear rates. $V_0$ is the applied shear velocity amplitude. Bacterial concentration is fixed at $n=50n_0$. The shear-rate amplitude ${\dot{\gamma }}_0=0.42$ s⁻¹ (black squares), 0.16 s⁻¹ (red circles), and 0.055 s⁻¹ (blue triangles). A Si wafer is used as the top plate. (B) Normalized shear profiles at different bacterial concentrations. ${\dot{\gamma }}_0$ is fixed at 0.16 s⁻¹. $n=10n_0$ (black squares), $40n_0$ (red circles), and $100n_0$ (blue triangles). To maintain bacterial motility at high $n$, a porous membrane is used as the top plate. The stop height, $h_s$, of the profile at $100n_0$ is indicated. Open squares are for a suspension of immobile bacteria at $100n_0$.