Electromechanical Modeling and Characterization of Ionic Polymer Benders

Abstract

This paper presents a coupled, electromechanical model of a Nafion-based ionic polymer transducer used in the cantilevered bender configuration. A comparison of simulatedandexperimental responses for a 0.2 mm 5.0 mm 17 mm actuator validates both the form of the model and the empirically determined model parameters. In one of the experiments used for parameter identification, the short circuit current is found to be proportional to the induced actuator velocity, with the constant of proportionality on the order of 10⁴A/(m/s). This dynamic model differs from those presented by other researchers in that it is able to represent the transducer as either a sensor or as an actuator. Also presented is an assessment of the polymer actuators’ ability to perform mechanical work. The results of a series of force versus deflection experiments are outlined, and energy densities are calculated to facilitate comparison with other actuator technologies. The maximum blockedforce with a 1.25 V step input was 1.6 mN (with a 17 mm actuator), andthe maximum free deflection with a 1.25 V step input was 1.8 mm (with a 22 mm actuator). The energy densities ranged from 1.1 to 12.8 mJ/kg and3.4E-06 to 4.0E-05 mJ/mm³ with an input range of 0.75–1.25 V.

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