A circuit to model the electrical behavior of an ionic polymer-metal composite

The electrical behavior of an ionic polymer-metal composite (IPMC), when a voltage is applied across its thickness, is investigated. IPMCs are new materials of increasing interest, to implement artificial muscles in robotic applications, and to implement displacement sensors in measurement fields. They are particularly light and they deform if electrically stimulated with a very low voltage; on the other hand they produce a voltage if mechanically bent. An understanding of the phenomena involved in electromechanical energy conversion may address research activity toward the building of innovative devices where both sensing and actuating functions could be integrated in the same material. The paper illustrates a model that describes the electrical behavior of an IPMC as an actuator using an equivalent circuit. It is a totally new nonlinear lumped parameter model which is able to describe all the phenomena observed in the flow of electrical current through the material, including nonlinear phenomena. The model has been validated by a large set of comparisons between simulations and experimental data. In all the cases analyzed the simulations agree with the experimental data.