Actuation of a novel Pluronic-based hydrogel: Electromechanical response and the role of applied current

A novel Pluronic-based hydrogel copolymer was synthesized and actuated. The combined properties of improved biocompatability and response to electrical excitation of this cross-linked gel make it a potential candidate for actuators such as electrically controllable occlusion devices and non-surgical implants. The electrical response of the copolymer was verified using bending tests performed in potassium chloride (KCl) solutions of different concentrations and the novel material was characterized using equilibrium swelling experiments, environmental scanning microscopy (ESEM) imaging, and a potentiometric method for estimating the fixed charge. We considered the influence of current, pH and concentration on the hydrogel actuator behavior, which was manifested in the degree of bending and in direction of bending. A reversal of the bending direction was observed twice in a single system under DC bias (without reversal of electric field polarity). We described this phenomenon as representing several different types of electric-responsive behavior that become dominant at different actuation stages of the polymer system. The distinction between the different actuation effects is important for the development of hydrogel actuators.