Swelling Characteristics of 3D-Arbitrary-Geometry of the pH-Sensitive Hydrogels

We present our simulation results of swelling responses of the pH-sensitive, 3D-arbitarary-geometry hydrogel in steady state conditions. The swelling responses of the hydrogels to the changes in environmental stimuli such as solution pH are discussed. The finite element simulation uses three nonlinear partial-differential equations for responsible physical phenomena namely- chemical for ionic transport across the hydrogel, electrical for local electric charge balance within hydrogel, and mechanical for expansion of the hydrogel by the Nernst-Planck, the Poisson’s, and the mechanical field equations respectively. In the case of pH-sensitive hydrogel, material properties such as modulus of elasticity and Poisson’s ratio changes with a change in surrounding environments. Finite element analysis used for present study was carried out by full coupling of above three partial-differential equations with variable material properties. Employing a moving mesh method for 3D geometry, the FEM simulation was performed to account for large-swelling of the pH-sensitive hydrogel. This highly nonlinear and computationally intensive simulation was performed using multicore parallel-processing computer. The simulation results using above mentioned strategy has been validated for 2D geometry and results are in agreement with other published experimental results.