Electroactive polymers for sensing

Wang, Tiesheng; Farajollahi, Meisam; Choi, Yeon Sik; Lin, I-Ting; Marshall, Jean E.; Thompson, Noel M; Kar‐Narayan, Sohini; Madden, John D. W.; Smoukov, Stoyan K.

doi:10.1098/rsfs.2016.0026

Cited by 169 publications

(115 citation statements)

References 227 publications

(329 reference statements)

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“…They are actuated by applying an electric field, converting electrical energy directly into mechanical work. Depending on the actuation mechanism, EAPs are grouped into two classes: ionic and electronic EAPs . In ionic EAPs, the application of an electric field results in oppositely charged ions to migrate through the polymeric film to the respective electrodes causing an up‐concentration of the sterically more demanding anions on one side and of the less demanding cations on the other side of this film .…”

Section: Introductionmentioning

confidence: 99%

Polar Elastomers as Novel Materials for Electromechanical Actuator Applications

2017

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Dielectric elastomer actuators are stretchable capacitors capable of a musclelike actuation when charged. They will one day be used to replace malfunctioning muscles supposing the driving voltage can be reduced below 24 V. This focus here is on polar dielectric elastomers and their behavior under an electric field. Emphasis is placed on all the features that are correlated with the molecular structure, its synthetic realization, and its impact on properties. Regarding the polymer class, the focus, to some degree, is on polysiloxanes because of their attractively low glass transition temperatures. This enables introduction of highly polar groups to the backbone while maintaining soft elastic properties. The goal is to provide a few guidelines for future research in this emerging field that may be useful for those considering entering this fascinating endeavor. Because of the large number of materials available, a few restrictions in the selection have to be applied.

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Section: Introductionmentioning

confidence: 99%

Polar Elastomers as Novel Materials for Electromechanical Actuator Applications

2017

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“…1) are soft active materials (SAMs) that produce reversible deformation (Zou et al, 2011) in response to external stimuli, such as a change in temperature, pH, light, electromagnetic fields, among others. Other examples of SAMs include, stimuli-responsive gels (Ahn et al, 2008;White et al, 2013), electroactive polymers (Scrosati et al, 1993;Wang et al, 2016), liquid crystal elastomers (Küpfer and Finkelmann, 1991;White and Broer, 2015) and shape memory polymers (Lendlein and Kelch, 2002;Hager et al, 2015). Growing technological applications of these materials in the areas of drug delivery, self assembly, therapeutics, biomedical engineering, soft robotics etc.…”

Section: Introductionmentioning

confidence: 99%

Mechanics of polymer brush based soft active materials– theory and experiments

Manav

Anilkumar

Phani

2018

Journal of the Mechanics and Physics of Solids

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Brush-like structures emerge from stretching of long polymer chains, densely grafted on to the surface of an impermeable substrate. They arise due to the competition between conformational entropic elasticity of polymer chains and excluded volume interactions from the intra and interchain monomer repulsions. Recently, stimuli responsive polymer brush based soft materials have been developed to produce controllable and reversible large deformations of the host substrate. To understand these systems, and improve their functional properties, we study elastic stress distribution and surface stress-curvature relations of a neutral polymer brush grafted on to an elastic beam, made of a soft material. In the strongly stretched brush regime, we combine mean field theory from polymer physics with a continuum mechanics model and show that the residual stress variation is a quartic function of distance from the grafting surface, with maximum stress occurring at the grafted surface. Idealizing the brush as a continuum elastic surface layer with residual stress, we derive a closed form expression for surface stress and the surface elasticity of the layer as a function of brush parameters, such as graft density and molecular weight. The generalized continuum beam model accounts for the Young-Laplace and Ogden-Steigman curvature elasticity correction terms, and yields a surface stress-curvature relation, which contains existing relations in the literature as special cases. Further, we report experiments on a thermoresponsive random copolymer brush, Poly(N-isopropylacrylamide)-co-Poly(N,N-Dimethylacrylamide) (PNIPAm-co-PDMA) brush, grafted on one side of a plasticized poly(vinyl chloride) (pPVC) thin film. Estimated surface stress from measured curvature is on the order of −10 N/m, and it decreases gradually, and reversibly, with increasing ambient temperature from 15 • C to 55 • C.

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“…As is well‐known that the capacitance of a parallel‐plate capacitor is proportional to 1/ d , where d is the spacing between plates. When the sensor was uniaxially stretched, the tensile train resulted in a shortened distance between the electrodes ( d ′), which led to a change in capacitance (Δ C ) . Figure b shows that the capacitance change (Δ C / C 0 ) of the sensor was linearly dependent on the applied strain (up to 100%).…”

Section: Resultsmentioning

confidence: 99%

Self‐Healable and Mechanically Reinforced Multidimensional‐Carbon/Polyurethane Dielectric Nanocomposite Incorporates Various Functionalities for Capacitive Strain Sensor Applications

Ling

Liu

et al. 2018

Macro Chemistry & Physics

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With the continuous development of wearable sensing devices utilized for human motion monitoring, structural health monitoring, and robotic systems, higher demands on a set of material properties of functional materials are placed. Moreover, high flexibility and self‐healability are indispensable properties in wearable electronic devices. Herein, a self‐healing flexible dielectric nanocomposite with various incorporated functionalities is described. Multidimensional carbons, that is, graphene and carbon nanotubes, are introduced into a self‐healing polyurethane matrix to obtain the healable dielectric nanocomposite which contributes to the capacitance response of the wearable sensors. The as‐prepared nanocomposite exhibits a dramatic increase in properties, which reach up to 10.50 ± 0.44 MPa for Young's modulus, 35.1 for dielectric constant at 103 Hz, and 1.67 W m−1 K−1 for the in‐plane thermal conductivity with low loading. More importantly, the nanocomposites display a unique ability to recover the structure and multiple properties after mechanical damages. In addition, a self‐healing capacitive strain sensor with the “sandwich” structure is prepared based on the nanocomposite. The strain sensor shows good sensitivity in a larger strain range (up to 100%), stable responsiveness, and healable ability.

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Electroactive polymers for sensing

Cited by 169 publications

References 227 publications

Polar Elastomers as Novel Materials for Electromechanical Actuator Applications

Polar Elastomers as Novel Materials for Electromechanical Actuator Applications

Mechanics of polymer brush based soft active materials– theory and experiments

Self‐Healable and Mechanically Reinforced Multidimensional‐Carbon/Polyurethane Dielectric Nanocomposite Incorporates Various Functionalities for Capacitive Strain Sensor Applications

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