Modeling the electrical impedance response of ionic polymer transducers

Abstract

Articles you may be interested inA physics-based model of the electrical impedance of ionic polymer metal composites J. Appl. Phys. 111, 124901 (2012) An analytical study is presented that investigates the electrical impedance response of the ionic polymer transducer. Experimental studies have shown that the electromechanical response of these active materials is highly dependent upon internal parameters such as neutralizing counterion, diluent, electrode treatment, as well as environmental factors such as ambient temperature. Further examination has shown that these variations are introduced predominantly through the polymer's ability to convert voltage into charge migration. This relationship can easily be represented by the polymer's electrical impedance as measured across the outer electrodes of the transducer. In the first half of this study an analytical model is developed which predicts the time and frequency domain characteristics of the electrical response of the ionic polymer transducer. Transport equations serve as the basis for this model, from which a series of relationships are developed to describe internal potential, internal charge density, as well as surface current. In the second half of this study several analytical studies are presented to understand the impact that internal parameters have on the polymer's electrical response, while providing a conceptual validation of the model. In addition to the analytical studies several experimental comparisons are made to further validate the model by examining how well the model predicts changes in temperature, viscosity and pretention within the ionic polymer transducer.

Bias-dependent model of the electrical impedance of ionic polymer-metal composites

“…The capacitor idealizes the phenomena of charge build up in the double layer region, the Warburg impedance is related to mass transfer at the interfaces, and the resistor is associated with ion transport in the ionomer bulk. In agreement with the majority of experimental observations in the literature, see for example [42,[46][47][48], the model predicts that the impedance magnitude decreases with a slope of approximately −10 dB/decade at low frequency and reaches an almost constant value for high frequency. The accuracy of the model has been validated through experimental results on Nafionbased IPMCs and comparison with alternative models for IPMC impedance [49][50][51].…”

A physics-based model of the electrical impedance of ionic polymer metal composites

“…[45][46][47] On the contrary, at lower frequencies, the dependence of the magnitude of the IPMC impedance on the frequency is characterized by variations slower than the typical À20dB=decade. In addition, the phase of such impedance typically does not converge to either 0 or 90 as the frequency approaches zero.…”

“…In addition, the phase of such impedance typically does not converge to either 0 or 90 as the frequency approaches zero. [45][46][47] Notably, this behavior cannot be satisfactorily interpreted by referring to simple capacitive or resistive effects. Notwithstanding the general interest in the development of simplified models for the analysis of the IPMC electrochemical behavior, a physics-based derivation of a comprehensive IPMC impedance model is currently lacking.…”

Influence of temperature on the impedance of ionic polymer metal composites

“…In [13,14], the effect of temperature on IPMC sensing is studied, and a similar analysis on IPMC actuation is presented in [15]. To the best of our knowledge, the effect of temperature on IPMC impedance has only been considered in [16], where a resistor-capacitor model is utilized for interpreting experimental findings.…”

“…While several studies have investigated the role of temperature on IPMCs [11][12][13][14][15][16], a systematic analysis of the effect of temperature on the impedance is currently lacking. For example, IPMC actuation at temperatures below zero degree celsius for cryogenic applications is demonstrated in [11].…”