Broadband dielectric spectrometry of liquids and biosystems

Kaatze, U.; Feldman, Yuri

doi:10.1088/0957-0233/17/2/r01

Cited by 165 publications

(101 citation statements)

References 142 publications

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“…One pair supplies current to the MUT while the other pair senses the potential difference across the sample. Provided that the sense electrodes draw negligible current, by using a high-impedance amplifier for example, the electrode polarization effect will be suppressed and low-frequency frequency measurements can be made reliably [8,26].…”

Section: Electrode Polarizationmentioning

confidence: 99%

“…Examples of materials characterized using the open-ended coaxial probe include, but are not limited to: biological tissues [1], tumors [2], binary mixtures of liquids [3], particle suspensions and emulsions [4], food [5], vegetation [6], and soil [7]. The advantages of the openended coaxial probe over other techniques are that it is a broadband measurement (10 5 -10 10 Hz), requires no sample preparation, and is suitable for liquid and semisolid samples [8].…”

Section: Introductionmentioning

confidence: 99%

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Permittivity Measurements of Biological Samples by an Open-Ended Coaxial Line

Bobowski¹,

Johnson²

2012

PIER B

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Abstract-We previously reported on the complex permittivity and dc conductivity of waste-activated sludge. The measurements, spanning a frequency range of 3 MHz to 40 GHz, were made using an open-ended coaxial transmission line. Although this technique is well established in the literature, we found that it was necessary to combine methods from several papers to use the open-ended coaxial probe to reliably characterize biological samples having a high dc conductivity. Here, we provide a set of detailed and practical guidelines that can be used to determine the permittivity and conductivity of biological samples over a broad frequency range. Due to the electrode polarization effect, low frequency measurements of conducting samples require corrections to extract the intrinsic electrical properties. We describe one practical correction scheme and verify its reliability using a control sample.

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Section: Electrode Polarizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Permittivity Measurements of Biological Samples by an Open-Ended Coaxial Line

Bobowski¹,

Johnson²

2012

PIER B

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“…For an experimental verification and further refinement of the theoretical approach, there is the need to determine the amount of liquid-like water and ice in soil below 0 • C. There are several techniques available for the characterization of the binding state of water in porous materials: nuclear magnetic resonance (NMR - Watanabe and Mizoguchi, 2002;Stillman et al, 2010;Watanabe et al, 2011), atomic force microscopy (AFM - Teschke et al, 2001), isothermal calorimetry (Anderson and Tiece, 1973) as well as broadband dielectric spectroscopy (BDS - Kaatze and Feldman, 2006). Especially the methods of broadband dielectric spectroscopy are sensitive for characterization of structural and dynamical properties of water in porous materials (Kupfer et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy

Lorek

Wagner

2013

The Cryosphere

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Abstract.Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 • C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to −70 • C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m 2 g −1 , up to 9.4 % w/w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m 2 g −1 , up to 7.4 % w/w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak highfrequency processes (bound or hydrated water as well as ice) and a strong low-frequency process due to counter-ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to −70 • C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.

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“…This notorious effect is very difficult to be eliminated, even though many methods 43,44 have been addressed on it. We tried some of these methods, but none of them is effectively applicable to the present case, maybe because parts of 6CB crystals were nucleated on the surface of the electrodes.…”

Section: E Complex Conductivity Spectramentioning

confidence: 99%

Liquid crystalline phase in ethanol suspension of anisometric 4-cyano-4-n-hexylbiphenyl microcrystals: Witnessed by dielectric spectroscopy

Chen

Nozaki

2010

The Journal of Chemical Physics

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The suspensions of 4-cyano-4-n-hexylbiphenyl ͑6CB͒ anisometric microcrystal were obtained by quenching homogeneous 6CB/ethanol mixtures with different 6CB concentrations. Such suspensions were strongly suggested from the differential scanning calorimetry examinations and the image observations of the samples during the quench and heating processes. The crystallization process for the mixtures with higher 6CB concentration looked like the isotropic-nematic phase transition of bulk liquid crystal. Dielectric measurement was carried out on the mixtures during the heating process after quench. Distinct dielectric relaxation was observed in the frequency range between kHz and 100 kHz, which exhibited obvious dependence on temperature and 6CB concentration. Curve fitting on the complex conductivity spectra indicates that three Debye type relaxations exist in this narrow frequency range. Based on the dependences of relaxation parameters on temperature and 6CB concentration, the possible relaxation mechanisms and the phase conformation of the mixtures were discussed. It was concluded that the relaxations, from high to low relaxation frequency, originate from the Maxwell-Wagner polarization, the rotation of 6CB microcrystal around its long axis, and the reorientation of 6CB microcrystal around its short axis, respectively. It was also confirmed that the quenched 6CB/ethanol mixtures show isotropic-nematic phase transition with the increase of 6CB concentration.

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Broadband dielectric spectrometry of liquids and biosystems

Cited by 165 publications

References 142 publications

Permittivity Measurements of Biological Samples by an Open-Ended Coaxial Line

Permittivity Measurements of Biological Samples by an Open-Ended Coaxial Line

Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy

Liquid crystalline phase in ethanol suspension of anisometric 4-cyano-4-n-hexylbiphenyl microcrystals: Witnessed by dielectric spectroscopy

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