Reaction, diffusion, electric conduction and determination of fixed ions in a hydrogel

Hegedűs, László; Wittmann, Mária; Kirschner, Norbert; Noszticzius, Zoltán

doi:10.1007/bfb0114397

Cited by 19 publications

(23 citation statements)

References 11 publications

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“…Nonlinear chemistry [1][2][3][4], engineered complexity [5], biological analogies, and possible analytical applications [6] motivated the research initiated in the past few years in the field of the electrolyte diodes and transistors [3,4,[6][7][8][9][10]. The "building block" of these devices is a hydrogel cylinder connecting reservoirs of two different electrolytes.…”

Section: A Background Of the Researchmentioning

confidence: 99%

“…This system behaves like a diode [6] because at positive polarities the gel is filled with conductive KCl solution whereas at negative polarities a high impedance region of pure water appears. From the CV characteristics of such a diode the fixed charge density can be also calculated [6], but with a different method and at a different pH. Based on these data the pK value of the acidic group fixed on the polymer chain can be determined.…”

Section: B Aims Of the Present Papermentioning

confidence: 99%

“…Another method to determine the fixed charge concentration in the gel is to measure its CV characteristics in an acid-base diode [6]. To this end the very same gel cylinder was applied, but now the two reservoirs contained 0.1 M KOH and 0.1 M HCl solutions connected via the hydrogel cylinder.…”

Section: Calculation Of the Fixed Charge Concentration From The Acmentioning

confidence: 99%

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Electrolyte diodes and hydrogels: Determination of concentration andpKvalue of fixed acidic groups in a weakly charged hydrogel

et al. 2004

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Current-voltage (CV) characteristics of polyvinyl alcohol (PVA)-glutardialdehyde hydrogel cylinders were measured in aqueous KCl solutions. To this end a new special apparatus was constructed where the gel cylinder connects two electrolyte reservoirs. The measured quantities are the electric current flowing through the gel and the potential difference between the two reservoirs. Concentration polarization near the gel-liquid interfaces is decreased considerably by applying an intense mechanical stirring in both reservoirs. Under these conditions below 1 V concentration polarization is negligible, and the CV curves are nearly straight lines. It was found that the gel applied here is a weakly charged anionic hydrogel. Concentration of fixed anions was determined from the slope of these lines measured in 0.001 and 0.01 molar KCl solutions. Fixed anion concentration of the same piece of gel was measured also with a different method, when the gel was used in an acid-base diode. In this case one reservoir contained 0.1 molar HCl, and the other 0.1 molar KOH. From the results of the two measurements, the concentration (4.45 x 10(-3) M) and the pK value (4.03) of the fixed acid groups responsible for the anionic character of the gel was calculated. The pK value is compatible with fixed carboxylic acid groups contaminating the PVA gel. Furthermore, concentration polarization phenomena in the boundary layers nearby the gel were studied in 0.001 M KCl solutions, measuring the diodelike CV characteristic of a gel cylinder, when stirring was applied only at one side of the gel. Boundary layers facing the cathode or the anode responded in a different way to stirring. The difference cannot be explained completely with the hypothesis of electroconvection suggested previously.

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Section: A Background Of the Researchmentioning

confidence: 99%

Section: B Aims Of the Present Papermentioning

confidence: 99%

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Electrolyte diodes and hydrogels: Determination of concentration andpKvalue of fixed acidic groups in a weakly charged hydrogel

et al. 2004

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“…6,10 Here we report only some additional observations on the nonlinear behavior of these novel devices.…”

Section: Methodsmentioning

confidence: 95%

Nonlinear effects of electrolyte diodes and transistors in a polymer gel medium

Hegedűs

Kirschner

Wittmann

et al. 1999

Chaos: An Interdisciplinary Journal of Nonlinear Science

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The polarization curve of an acid-base interface in a hydrogel medium has a diode characteristic. Two of each such electrolyte diodes can be combined to give an electrolyte transistor. When a salt is added to the alkaline or to the acidic part of a reverse biased electrolyte diode, the current response is highly nonlinear. If the salt is added to the acidic side, even bistability can be observed. This bistability can generate complex oscillations in a base-acid-base electrolyte transistor. These nonlinear effects are studied experimentally and theoretically. While the nonlinear salt effect can be explained with the Nernst-Planck equations, to understand the bistable behavior further investigations are necessary. (c) 1999 American Institute of Physics.

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“…Intensive research on the ionic current rectification at a junction of acidic and basic electrolytes has been conducted. [22][23][24][25][26] The rectifying junction of these electrolyte diodes is formed in the hydrogel bridge which connects two electrolyte reservoirs. During reverse bias, where positive potential is applied to the electrode in the acid solution, H þ and OH À ions migrating from the electrolytes form water at the interface, where the ion concentration is drastically reduced.…”

Section: Ionic Diodesmentioning

confidence: 99%

Ionic current devices—Recent progress in the merging of electronic, microfluidic, and biomimetic structures

Koo

Velev

2013

Biomicrofluidics

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We review the recent progress in the emerging area of devices and circuits operating on the basis of ionic currents. These devices operate at the intersection of electrochemistry, electronics, and microfluidics, and their potential applications are inspired by essential biological processes such as neural transmission. Ionic current rectification has been demonstrated in diode-like devices containing electrolyte solutions, hydrogel, or hydrated nanofilms. More complex functions have been realized in ionic current based transistors, solar cells, and switching memory devices. Microfluidic channels and networks-an intrinsic component of the ionic devices-could play the role of wires and circuits in conventional electronics.

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Reaction, diffusion, electric conduction and determination of fixed ions in a hydrogel

Cited by 19 publications

References 11 publications

Electrolyte diodes and hydrogels: Determination of concentration andpKvalue of fixed acidic groups in a weakly charged hydrogel

Electrolyte diodes and hydrogels: Determination of concentration andpKvalue of fixed acidic groups in a weakly charged hydrogel

Nonlinear effects of electrolyte diodes and transistors in a polymer gel medium

Ionic current devices—Recent progress in the merging of electronic, microfluidic, and biomimetic structures

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