Modeling and simulation of the deformation of multi-state hydrogels subjected to electrical stimuli

In this paper, a mathematical model capable of simulating pH-sensitive hydrogels is refined to extend its application to electric-sensitive hydrogels. This is achieved by consideration for large deformation as well as the reformulation of the fixed charge density. The present model, termed the refined multi-effect-coupling electric-stimulus (rMECe) model, consists of nonlinear partial differential governing equations with chemo-electro-mechanical coupling effects and the fixed charge density, which includes the effect of externally applied electric field. A comparison between simulation results and experimental data is carried out so as to validate the rMECe model, and very good agreement is observed. The multi-state rMECe model accurately predicts the responsive deformation of the hydrogels when placed in a bath solution, which is subjected to externally applied electric field. The influences of several physical parameters, such as the applied voltage, initial fixed charge density and ionic concentration of surrounding solution, are examined and discussed in detail.