  We investigate the system size dependent rheological response of branched
type I collagen gels. When subjected to a shear strain, the highly
interconnected mesh dynamically reorients, resulting in overall stiffening of
the network. When a continuous shear strain is applied to a collagen network,
we observe that the local apparent modulus, in the strain-stiffening regime, is
strongly dependent on the gel thickness. In addition, we demonstrate that the
overall network failure is determined by the ratio of the gel thickness to the
mesh size. These findings have broad implications for cell-matrix interactions,
the interpretation of rheological tissue data, and the engineering of
biomimetic scaffolds.
