Soft and wet touch‐sensing system made of hydrogel

Sawahata, K.; Gong, Jian Ping; Osada, Yoshihito

doi:10.1002/marc.1995.030161002

Cited by 51 publications

(34 citation statements)

References 7 publications

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“…Superabsorbent polymers can be used in sensor systems by virtue of their swellability and rubbery nature, which are controllable by changes in water content, pH, and ionic strength. Because a small voltage may be induced in a soft hydrogel by applying mechanical stress to the gel, a pressure-sensitive switch is possible (81). The potential that develops between the stressed and unstressed parts of the gel generates a signal that can light a photo diode.…”

Section: Disposable Infant Diapersmentioning

confidence: 99%

Superabsorbent Polymers

Buchholz¹

2006

Encyclopedia of Polymer Science and Technology

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IntroductionSuperabsorbent polymers are very high molecular mass, cross-linked Polyelectrolytes (qv) that can absorb or imbibe more than ten times their mass of water or aqueous solutions. In order to absorb this large quantity of aqueous fluid, the polymers must be only slightly cross-linked so that the polymer chains can adopt widely spaced configurations. And in order to remain largely insoluble, while at the same time being highly expanded, the polymer chains must have very high molecular mass so that the small number of cross-links connect together all the chains. Cross-linked polyelectrolytes absorb more aqueous liquid than do neutral polymers as a result of the added osmotic, swelling pressure of the counterions that balance the high electric charge of the ionized functional groups spaced along the polymer chains (see POLYELECTROLYTES).Although any high molecular mass, cross-linked polyelectrolyte can function as a superabsorbent polymer, the commercially available superabsorbent polymers are alkali metal salts of poly(acrylic acid) cross-linked with multifunctional cross-linkers (see ACRYLIC (AND METHACRYLIC) ACID POLYMERS). Most often the cross-links are formed from comonomers that are incorporated into the polymer during the free-radical-initiated addition polymerization. Common cross-linkers are di-and tri-acrylates or methacrylates. The polymer chains can also be crosslinked after the main polymer chains have been formed. In this case, the crosslinker is multifunctional with groups that can react with the carboxylic acid or carboxylate groups present along the polymer chains. Examples of this type of cross-linker are polyols, polyepoxides, polyamines, and the like. Most commonly, the polymers are made by means of free-radical-initiated polymerization of an aqueous solution of the monomers, followed by drying the hydrogel that is formed and grinding the dry polymer to a granular powder.The principal use of superabsorbent polymers is as a liquid absorbent in disposable hygiene products, which include baby diapers, feminine hygiene products, and adult incontinence products. Smaller volume uses include liquid absorbent pads for packaged meats and water-blocking tapes and coatings for electrical and telecommunication cables.

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Section: Disposable Infant Diapersmentioning

confidence: 99%

Superabsorbent Polymers

Buchholz¹

2006

Encyclopedia of Polymer Science and Technology

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“…Both polyelectrolyte gels and analogous ionic-polymer-metal composites (IPMC) can generate electrical potential in response to a mechanical deformation. [1][2][3][4] The mechanism has been ascribed to changes in the degree of ionization [1] or changes in the effective dipole moment induced by mechanical deformation of the polymer. [4] Inherently conducting polymers (ICPs) are unique p-conjugated polymers with an alterable electrical conductivity approaching that of metal.…”

Section: Introductionmentioning

confidence: 99%

Soft Mechanical Sensors Through Reverse Actuation in Polypyrrole

Alici

Madden

et al. 2007

Adv Funct Materials

102

103

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The phenomenon of voltage generated from a soft sensor using polypyrrole in response to mechanical deformation is described and investigated. The sensor consists of two polypyrrole layers in contact with an electrolyte and operates in bending mode in air. The magnitude and sign of the induced voltage was found to depend on the type of dopant counter‐ions and the nature of the surrounding electrolyte. The mechanical sensor response is shown to be a “reverse actuation”, generating millivolt signals for millimeter sized deflections or ∼ 1000 C m–3 charge for 1 % strain in the polypyrrole layer. A model based on ‘Deformation Induced Ion Flux' has been proposed whereby the strain induced volume change in the polymer produces a shift in the Donnan equilibrium between mobile dopant ions inside the polymer and in the external electrolyte. A simple thermodynamic model provides reasonable estimates of the size of the voltage and charge produced.

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“…The reverse process has also been previously reported, 30 and it produces electrical potential from mechanical deformation. As shown in Fig.…”

Section: Mechanoelectrical Effects Of Hydrolysed Npc Gelsmentioning

confidence: 85%

Kinetic aspects, rheological properties and mechanoelectrical effects of hydrogels composed of polyacrylamide and polystyrene nanoparticles

et al. 2007

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Snake-cage gels were prepared using monodisperse polystyrene (PS) nano-sized particles (R = 200 nm) in place of the more commonly used linear polymer. The kinetics of the formation of the complementary polyacrylamide (PAM) hydrogel was studied alone or in the presence of the PS nanoparticles by 1 H-NMR. Without PS, the reactivity ratios of the acrylamide (Am) and the cross-linking agent N,N9-methylene-bisacrylamide (BisAm) were computed using the initial kinetics of PAM gel at high cross-linker concentration (r A = 0.52 and r B = 5.2 for Am and BisAm, respectively). In the presence of PS, during the formation of nanoparticle composite (NPC) gels, there was a decrease in the conversion rate with an increasing fraction of PS nanoparticles. This could be explained by steric effects, which induce an increase of the elastic modulus of the matrix with the increasing fraction of PS nanoparticles. There was a considerable increase in the rheological properties of the NPC gels (i.e. tensile modulus), which was more pronounced at higher fractions of nanoparticles. We used particular mechanical properties to develop a stimulus-responsive (''smart'') material, i.e. a mechanoelectrical effect, which may be used in the development of soft and wet tactile-sensing devices.

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Soft and wet touch‐sensing system made of hydrogel

Cited by 51 publications

References 7 publications

Superabsorbent Polymers

Superabsorbent Polymers

Soft Mechanical Sensors Through Reverse Actuation in Polypyrrole

Kinetic aspects, rheological properties and mechanoelectrical effects of hydrogels composed of polyacrylamide and polystyrene nanoparticles

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