Electrical impedance controls mechanical sensing in ionic polymer metal composites

Youngsu Cha, Filippo Cellini, Maurizio Porfiri

Research output: Contribution to journalArticle

Abstract

Ionic polymer metal composites (IPMCs) are a class of soft electroactive materials that are recently finding extensive application as mechanical sensors and energy harvesters in liquids. In their most fundamental form, IPMCs are composed of a hydrated ionomeric membrane that is sandwiched between two electrochemically deposited metal electrodes. Ionomer swelling, counterion diffusion, and the formation of electric double layers are some of the physical phenomena underpinning energy transduction in IPMCs; however, a thorough understanding of the relative influence of such phenomena is yet to be established. Here, we propose a physics-based modeling framework, based on the Poisson-Nernst-Planck system, to describe IPMC chemoelectrical response to an imposed time-varying flexural deformation. We utilize the method of matched asymptotic expansions to compute a closed-form solution for the electric potential and counterion concentration in the IPMC. The model predicts that IPMC sensing is independent of the time rate of deformation and linearly correlated to the mechanical curvature, with a coefficient of proportionality that is a function of the ionomer thickness and the temperature. Thus, our results demonstrate that the characterization of IPMC electrical impedance suffices to identify all the parameters that are relevant to sensing, in contrast with the current state of knowledge. Theoretical results are validated through experiments on patterned in-house fabricated IPMC samples that are subject to time-varying flexural deformations.

Original languageEnglish (US)
JournalPhysical Review E
Volume88
Issue number6
DOIs
StatePublished - Dec 23 2013

Fingerprint

Impedance Control
Ionic Polymer-metal Composite
electrical impedance
Sensing
composite materials
polymers
metals
Time-varying
Matched Asymptotic Expansions
Swelling
Electric Potential
Energy
Closed-form Solution
Impedance
Electrode
swelling
Siméon Denis Poisson
Membrane
Linearly
Metals

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Statistical and Nonlinear Physics
  • Statistics and Probability

Cite this

Electrical impedance controls mechanical sensing in ionic polymer metal composites. / Cha, Youngsu; Cellini, Filippo; Porfiri, Maurizio.

In: Physical Review E, Vol. 88, No. 6, 23.12.2013.

Research output: Contribution to journalArticle

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