Numerical and Experimental Characterization of Electroactive Response of the Sclera Tissue

In this dissertation, the flattening of the posterior of the eye globe was studied by developing an axisymmetric finite element model to investigate the role of several mechanical parameters to the flattening of the posterior of the eye globe by performing large scale parametric study. The main focus of the next chapters was investigation on the electroactive response of the sclera tissue. It was shown that the sclera, as a natural polyelectrolyte hydrogel which is negatively charged, responds to the external electrical stimulation if the tissue is placed inside salt solution between two electrodes. The electromechanical response of the sclera was characterized by the mechanical bending response of the samples under the electrical stimulation. A coupled chemo-electro-mechanical model was developed in order to simulate this phenomenon based on finite element method. The developed numerical tool was tuned against the experimental results using an inverse approach based on optimization and later was used to study the effect of several parameters including the magnitude of the electric field, negative fixed charges of the tissue, orientation and concentration of the collagen fibers in determination of the electromechanical response of the sclera tissue. The numerical model was improved from a semi coupled model to a fully coupled model in order to consider large deformation in electroactive hydrogels using moving mesh technique. The new developed model was later used in order to investigate the profile of the bending angle over the length of the sclera strip.