The Use of Active Ionic Polymers in Dynamic Skin Friction Measurements

Etebari, Ali; Akle, Barbar J.; Farinholt, Kevin; Bennet, M.; Leo, Donald J.; Vlachos, Pavlos P.

doi:10.1115/ht-fed2004-56837

Cited by 8 publications

(3 citation statements)

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“…In the early 1990s, it was documented that ionic polymer transducer can exhibit coupling between the electrical and mechanical domains [1]. Following this work, there were numerous studies of the potential applications of ionic polymer transducers as sensors or actuators [2,3]. Until recently, the most accepted mechanism behind IPT actuation is that cations carrying water move across to the cathode while anions remain attached to the fluorocarbon matrix, which results in the local deformation of the IPT.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of ion transport of the high strain ionomer with conducting powder electrodes

Leo

2007

Modeling, Signal Processing, and Control for Smart Structures 2007

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The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers (IPT). At low frequency, strain response is strongly related to charge accumulation at the electrodes. Experimental results demonstrated using conducting powder, such as single-walled carbon nanotubes (SWNT), polyaniline (PANI) powders, high surface area RuO 2 , carbon black electrodes etc. as an electrode increases the mechanical deformation of the IPT by increasing the capacitance of the material. In this paper, Monte Carlo simulation of a twodimensional ion hopping model has been built to describe ion transport in the IPT. The shape of the conducting powder is assumed to be a sphere. A step voltage is applied between the electrodes of the IPT, causing the thermally-activated hopping between multiwell energy structures. Energy barrier height includes three parts: the energy height due to the external electric potential, intrinsic energy, and the energy height due to ion interactions. Finite element method software-ANSYS is employed to calculate the static electric potential distribution inside the material with the powder sphere in varied locations. The interaction between ions and the electrodes including powder electrodes is determined by using the method of images. At each simulation step, the energy of each cation is updated to compute ion hopping rate which directly relates to the probability of an ion moving to its neighboring site. Simulation ends when the current drops to constant zero. Periodic boundary conditions are applied when ions hop in the direction perpendicular to the external electric field. When an ion is moved out of the simulation region, its corresponding periodic replica enters from the opposite side. In the direction of the external electric field, parallel programming is achieved in C augmented with functions that perform message-passing between processors using Message Passing Interface (MPI) standard. The effects of conducting powder size, locations and amount are discussed by studying the stationary charge density plots and ion distribution plots.

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Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of ion transport of the high strain ionomer with conducting powder electrodes

Leo

2007

Modeling, Signal Processing, and Control for Smart Structures 2007

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“…In the early 1990s, it was documented that IPT can exhibit coupling between the electrical and mechanical domains (Salomon et al, 1992). Following this work, there were numerous studies of the potential applications of the ''smartness'' of ionic polymer transducers as sensors or actuators (Bar-Cohen, 2003;Buechler and Leo, 2004;Etebari et al, 2004;Keshavarzi et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Multi-scale modeling of ion transport in high-strain ionomers with conducting powder electrodes

Leo

Akle

2013

Journal of Intelligent Material Systems and Structures

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Ionomeric polymer transducers exhibit electromechanical coupling capabilities. The ion transport due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers. In this article, a two-dimensional Monte Carlo simulation of ion hopping has been developed to describe ion transport in materials that have fixed and mobile charge similar to the structure of the ionic polymer transducer. Such Monte Carlo simulations were performed to study the influence of conducting powder electrodes on stationary ion distribution in actuation. Ion accumulation around the powder sphere at the cathode is clearly observed in simulation results. Moreover, based on the unique property of stationary charge density of ionomeric polymer transducers in actuation, this article proposed a novel multi-scale model connecting Monte Carlo simulation for the material boundaries and a continuum model for the central part. To validate this multi-scale model, the simulation results are compared with experimental measurements. Both transient and steady-state responses from the experiments show reasonable agreement with those from the multi-scale model.

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“…Interest in polymeric actuators, sensors, and super capacitors has increased dramatically over the past few years because of their diverse applications that include artificial muscles, 1 shear flow sensing, 2 and charge carrying species for electrical applications. 3 Ionic copolymer ͑ionomer͒ electromechanical transducers have historically been based on low modulus Nafion materials.…”

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confidence: 99%

Directly Copolymerized Poly(arylene sulfide sulfone) and Poly(arylene ether sulfone) Disulfonated Copolymers for Use in Ionic Polymer Transducers

Wiles

Akle

Hickner³

et al. 2007

J. Electrochem. Soc.

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Polymeric electromechanical transducers were identified and based on various novel ion-exchange membranes bonded between two conductive metal layer electrodes. Imposed deformations and small electric fields allowed both sensing and actuation applications. Soft actuator materials produced large bending displacements when only a small voltage was applied across the membrane electrode assembly. Charge motion from one pole to the other pole produced electromechanical coupling effects in the ionic materials through the electric double layer. By increasing the surface area of the electrodes, thereby increasing the capacitance, it was shown that the motion of charges and actuator performance increases, thus indicating a strong correlation between the capacitance and charge motion/performance. Manipulation of the morphology of the electrodes by enhancing the capacitance and effective interfacial area of the conductive electrodes produced major effects on performance and transduction. Transducer actuation performance at lower frequencies was enhanced by employing a novel electrode fabrication technique which could utilize RuO 2 instead of platinum. At higher frequencies, mass transport and interfacial resistance appeared to play pivotal roles in actuator performance.Interest in polymeric actuators, sensors, and super capacitors has increased dramatically over the past few years because of their diverse applications that include artificial muscles, 1 shear flow sensing, 2 and charge carrying species for electrical applications. 3 Ionic copolymer ͑ionomer͒ electromechanical transducers have historically been based on low modulus Nafion materials. These transducers contain flexible sulfonic acid ion-exchange membranes having conductive metal electrodes plated to the outer surfaces ͑Fig. 1͒. Electromechanical coupling occurs under application of an electric field where physical deformations of the material produces actuation and sensing. 4 Relative to standard piezoelectric materials, which produce small strains at very large potentials ͑50 to Ͼ 1000 V͒, polymer transducers produce a higher strain output at greater than 1%, lower voltage operation at 1-4 V and high sensitivity when used in charge-sensing mode. Polyelectrolyte membranes typically consist of ion-containing pendent groups that are covalently bound to the copolymer backbone. These pendent moieties allow for some nanophase separation and charge aggregation, that permits selective ion-exchange through ion-hopping and/or ion-host transport. The hydrophilic clusters/channels of the ion containing groups allow for transport and the hydrophobic backbones allow for tough and ductile physical properties. Nafion and other alternative ion exchange membranes consist of covalently bound sulfonate moieties ͑anions͒ and very labile cations, typically protons. Therefore, the selectivity of the materials can be tailored to improve cation transport ͑e.g., H + , Li + , Na + ͒ while the anions are fixed.Soft actuator materials based on ionic polymer transducers can produce large be...

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The Use of Active Ionic Polymers in Dynamic Skin Friction Measurements

Cited by 8 publications

References 0 publications

Monte Carlo simulation of ion transport of the high strain ionomer with conducting powder electrodes

Monte Carlo simulation of ion transport of the high strain ionomer with conducting powder electrodes

Multi-scale modeling of ion transport in high-strain ionomers with conducting powder electrodes

Directly Copolymerized Poly(arylene sulfide sulfone) and Poly(arylene ether sulfone) Disulfonated Copolymers for Use in Ionic Polymer Transducers

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