Frequency-Dependent Electrical Conductivity of Concentrated Dispersions of Spherical Colloidal Particles

Bradshaw‐Hajek, Bronwyn H.; Miklavcic, Stanley J.; White, Lee R.

doi:10.1021/la703777g

Cited by 16 publications

(38 citation statements)

References 26 publications

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“…The beginnings of EIS can be traced to the work of Heaviside and Warburg, more than a century ago. Applications are as diverse as the investigation of corrosion processes (when the results of Epelboin and co-workers [18] in the 1960s propelled EIS into the forefront as a corrosion mechanism analytic tool [1,74,98,133]), the properties of dissolved polymers [54,62,63,78,88,118,134,136] and colloidal systems [9,12,17,19,29,39,53,112,115,128]. The latter two topics directly connect to the biosciences as suspensions of isolated cells represent a special case of colloidal suspensions: accordingly, DRS and EIS are emanating techniques nowadays that are applied to colloidal systems including dissolved polymers [50,51,56,62,63,87,88,89,90,135,137] and cell suspensions [3,20,30,39,42,43,69,75,80,86,…”

Section: Resultsmentioning

confidence: 99%

“…11.2) and can be envisaged as a dissolved dipole by its own. Thus, another type of polarization will additionally be caused by a redistribution of the ions along polar interfaces, causing the formation of Stern and Helmholtz layers [12,19,69,93,97,100,138]. In the example of Fig.…”

Section: Electric Dipole Layersmentioning

confidence: 99%

“…Since the times of Debye, the investigation of the frequency-dependent response of dipole systems became the basis of the emanating techniques of dielectric spectroscopy or electrochemical impedance spectroscopy [12,19,52,58,69,85,93,96,104,109,110,112,114,[118][119][120]138]. The names essentially result from the different application communities: dielectric spectroscopy focuses on the spectroscopic aspect that considers the dipole relaxations as a peculiar part within the total dielectric spectrum (this starts with the classical dipole relaxations and continues into the resonance spectra of the high-frequency regions that are dominated by quantum mechanical effects).…”

Section: Experimental Set-upmentioning

confidence: 99%

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Bioimpedance Spectroscopy

Klösgen

Rümenapp

Gleich

2011

BetaSys

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In the context of biology, electrical phenomena are usually identified with ionic currents through protein channels, for example as they are postulated during nerve signalling (Andersen et al. Prog Neurobiol 88(2):104-113, 2009; Sakmann and Neher Annu Rev Physiol 46:455-472, 1984). However, there are more electrical phenomena that play a significant role in biological systems, namely those arising from polarization effects (Grimnes Bioimpedance and Bioelectricity, 2008; Polk Handbook of Biological Effects of Electromagnetic Fields 1996). Local inhomogeneities in charge distributions give rise to the formation of permanent molecular dipoles as in uncharged molecules such as (hydration) water, or due to the polar groups in proteins and lipid molecules. Non-permanent electrical dipoles can originate from the presence of ions in solution. Structured distributions of counter-ions at all polar interfaces, for example along the surface of proteins and especially along the polar membrane interfaces of cells, cause the formation of Stern and Helmholtz layers. All non-uniform distributions of charges and dipoles initiate and modify internal local electrical fields. Moreover, the application of external fields causes relaxation processes with characteristic contributions to the frequency-dependent complex dielectric constant. These dipolar relaxations were initially described by Debye (

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Section: Resultsmentioning

confidence: 99%

Section: Electric Dipole Layersmentioning

confidence: 99%

Section: Experimental Set-upmentioning

confidence: 99%

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Bioimpedance Spectroscopy

Klösgen

Rümenapp

Gleich

2011

BetaSys

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“…Particle transport through macroscopic vessels can occur under the action of gravity (sedimentation) [ 19 , 20 ], of an applied electric field (electrophoresis) [ 21 , 22 ] or of a fluid flow (convection) [ 23 ]. We have investigated particle transport in longitudinally asymmetric capillaries assuming the action of both diffusive and convective mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Convective and diffusive effects on particle transport in asymmetric periodic capillaries

et al. 2017

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We present here results of a theoretical investigation of particle transport in longitudinally asymmetric but axially symmetric capillaries, allowing for the influence of both diffusion and convection. In this study we have focused attention primarily on characterizing the influence of tube geometry and applied hydraulic pressure on the magnitude, direction and rate of transport of particles in axi-symmetric, saw-tooth shaped tubes. Three initial value problems are considered. The first involves the evolution of a fixed number of particles initially confined to a central wave-section. The second involves the evolution of the same initial state but including an ongoing production of particles in the central wave-section. The third involves the evolution of particles a fully laden tube. Based on a physical model of convective-diffusive transport, assuming an underlying oscillatory fluid velocity field that is unaffected by the presence of the particles, we find that transport rates and even net transport directions depend critically on the design specifics, such as tube geometry, flow rate, initial particle configuration and whether or not particles are continuously introduced. The second transient scenario is qualitatively independent of the details of how particles are generated. In the third scenario there is no net transport. As the study is fundamental in nature, our findings could engender greater understanding of practical systems.

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“…In this paper, a first step is taken toward quantifying the electrical conductivity and streaming current of droplet-hydrogel composites as promising macroscopic transport properties for characterizing droplet-hydrogel interfaces. Even though the oscillatory electrical conductivity and streaming current of droplet-hydrogel composites are of importance for the characterization of droplet-hydrogel interfaces [24,25], knowledge of the steady responses is required before theories for the dynamic electrical conductivity and streaming current of droplet-hydrogel composites can be developed.…”

Section: Introductionmentioning

confidence: 99%

Transport in droplet-hydrogel composites: response to external stimuli

Mohammadi

2014

Colloid Polym Sci

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Determination of effective transport properties of droplet-hydrogel composites is essential for various applications. The transport of ions through a droplet-hydrogel composite subjected to an electric field is theoretically studied as an initial step toward quantifying the effective transport properties of droplet-hydrogel composites. A three-phase electrokinetic model is used to derive the microscale characteristics of the polyelectrolyte hydrogel, and the droplet is considered an incompressible Newtonian fluid. The droplethydrogel interface is modeled as a surface, which encloses the interior fluid. The surface has the thickness of zero and the electrostatic potential ζ . Standard averaging procedures are used to derive the effective governing equation for the current density that captures the macroscopic behavior. The results show that the polymer boundary condition has a modulating impact on the electrical conductivity, and the influence of the boundary condition decreases as the interior fluid viscosity increases. At the limit of the polymer's no-slip boundary condition, the interior and exterior fluids' viscosities, Brinkman screening length, and ionic strength have a significant impact on the conductivity. Interestingly, it should be possible to determine the ζ -potential for a droplet-hydrogel composite from measurements of the electrical conductivity with the aid of the formula derived for the conductivity. Finally, the theoretical study for determining the response of droplet-hydrogel composites to an imposed pressure gradient is undertaken, and it is found that the polymer boundary condition has a modulating impact on the response.A. Mohammadi ( )

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Frequency-Dependent Electrical Conductivity of Concentrated Dispersions of Spherical Colloidal Particles

Cited by 16 publications

References 26 publications

Bioimpedance Spectroscopy

Bioimpedance Spectroscopy

Convective and diffusive effects on particle transport in asymmetric periodic capillaries

Transport in droplet-hydrogel composites: response to external stimuli

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