Modeling of ICPF (ionic conducting polymer gel film) actuator (1st report, fundamental characteristics and black-box modeling)

An ionic conducting polymer gel film (ICPF) actuator is a composite of a perfluoro-sulfonic acid membrane sandwiched between platinum layers. Bending motion is induced by applying voltage between the surfaces in water of in wet conditions. This phenomenon was discovered in 1992. After reaching the maximum displacement toward the anode immediately, the actuator bent back to the cathode side, and approached the initial position gradually when a step voltage was applied. Current through the actuator decreased exponentially. The maximum displacement was proportional to the magnitude of the step voltage. Motion induced by a step current was almost the same as that induced by a step voltage but was slower. Voltage induced by the current increased gradually and reached a certain value, then increased once more to a steady voltage. The motion did not depend on the direction on the surface. The bending occurred in all directions. Larger displacement was observed near the electrode. Dynamics of the actuator was expressed in terms of a 4th-degree transfer function by black-box linear modeling. Simulation results were in good agreement with the experimental results.