Figure 4.

Strain-stiffening transitions of fibrin gels. (A) Critical strain characterizing the onset of the first strain-stiffening regime (regime 2), compared with a model (line) that assumes entropic stretching of fibers (Inset). (B) Critical stress characterizing the onset of the first strain-stiffening regime (regime 2, blue squares) and the onset of the second strain-stiffening regime (regime 4, red circles). Solid lines indicate model predictions for entropic stretching of fibers (blue line) and of loose protofibril bundles (red line and inset).