Non-linear elasticity of fibrin. In response to compression, the shear elastic modulus (G′) of a fibrin network first decreases, followed by a dramatic increase of the stiffness at compressive strains γ>0.8. At the maximal compressions (γ>0.9), fibrin networks display more than a 100-fold increase in the shear elastic modulus compared to their uncompressed states. The degree of compression (compressive strain, γ) is defined as the absolute fractional decrease in fibrin clot thickness, , where ΔL = L – L0, and L0 and L are the initial and reduced thickness dimensions of the uncompressed and compressed clots, respectively. (Adapted from Kim, et al. [50])