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.