Effective stiffness of thin nonlinear gel substrates

Experimental evidence and computational studies of cells cultured on very thin, soft substrates clearly demonstrate that the distance that cell-generated stresses and strains extend into soft culture substrates is considerable. The goal of this work is to examine the effect of nonlinear stiffness on the transmission of stresses and strains in soft culture substrates. Simulated cell tractions are applied to a nonlinear material model representing a fibrin gel utilizing finite element analysis and compared to a linear model. Simulations indicate that nonlinear behavior blunts stress transmission and extends strain fields, although the maximum displacements are decreased. These results have implications for modulating the effective stiffness experienced by cells cultured on soft protein gels.