Linear Electromechanical Model of Ionic Polymer Transducers -Part II: Experimental Validation

A series of experiments are performed to assess the validity of an equivalent circuit model of ionic polymer transducers. The fundamental parameters of the model are the dielectric permittivity of the material, the viscoelastic modulus, and the effective strain coefficient of the transducer. The results demonstrate the validity of a simplifying assumption regarding the reflected impedance of the polymer. This allows us to use a simpler set of expressions to predict the time and frequency response of the polymer. The expressions for sensing and actuation are verified in a series of step response and frequency response tests of cantilevered transducers. The curvefit algorithm used for parameter identification works well but there is always a tradeoff in accuracy between the time domain and frequency domain measurements. This could imply the existence of an input-level dependence on the parameters. In spite of this level dependence, the linear model is able to predict the response of an input-output pair that is independent of the parameter identification. This result supports the validity of the linear model. Experimental results also support the use of a reciprocal model in which each expression for actuation has a dual expression for sensing. Scaling experiments verify the predictions of the model with respect to changes in transducer length and width.