Diagram of the cell detachment device and characteristic detachment profile.

(A) Cells are allowed to settle onto a fibronectin-coated matrix atop the rotating stage. Motion of the stage and matrix induces fluid flow that generates a range of detachment forces that dislodges cells. (B) The surface density of pK1 after a 10-minute spin is plotted versus radial position showing that fewer cells remain attached near the circumference where the detachment force, τ, is high compared to the center where the detachment force approaches zero. (C) Fraction of adherent pK1 cells in panel B, normalized to the cell count at the center after a 10-minute spin is plotted versus surface shear stress, τ. Cells were incubated on BSA alone (▾) or in the presence of fibronectin (). (–○–) represents a curve fitted to the experimental points. The dashed line represents an adherent fraction of 0.5. The critical shear stress (τ₅₀) is defined as the point on the abscissa (shear stress) that corresponds to an adherent fraction of 0.5 along the fitted curve.