From modeling to implementation of a method for restraining back relaxation in ionic polymer-metal composite soft actuators

Ionic polymer-metal composites are an emerging kind of electroactive polymer actuators, which can bend in response to a relatively low driving voltage. However, to enhance the actuation performance of ionic polymer-metal composites, some of their drawbacks should be considered. One of the most important drawbacks is back relaxation. The so-called back relaxation effect means, when a step input voltage is applied to the ionic polymer-metal composite, the conventional bending displacement toward the anode is followed by an unwanted and slow back relaxation toward the cathode. Control-based methods for restraining the ionic polymer-metal composite back relaxation effect are feedback-based schemes which apply significant constraints to dominant applications of ionic polymer-metal composite actuators especially in biomedical applications. In this article, we present an entirely scientific-based mathematical modeling to achieve a practical method for restraining the back relaxation effect in Nafion-based ionic polymer-metal composites, relying on creating a specific pattern on Pt layers of the ionic polymer-metal composites and applying a local Gaussian disturbance to this patterned ionic polymer-metal composites.