In VivoDielectric Analysis of Free Water Content of Biomaterials by Time Domain Reflectometry

Naito, Satoru; Hoshi, Masato; Mashimo, Satoru

doi:10.1006/abio.1997.2256

Cited by 32 publications

(37 citation statements)

References 28 publications

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“…Permittivity of the skin was determined from the frequency dependence of the reflection coefficient in the presence of the dielectric plate. Another method, time domain reflectometry, based on measuring the changes in the waveform of the reflected pulse, was also useful for determination of skin permittivity and water content [Mashimo et al, 1987;Naito et al, 1997].…”

Section: Introductionmentioning

confidence: 99%

Human skin permittivity determined by millimeter wave reflection measurements

Алексеев

Ziskin

2007

Bioelectromagnetics

166

156

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Millimeter wave reflection from the human skin was studied in the frequency range of 37-74 GHz in steps of 1 GHz. The forearm and palm data were used to model the skin with thin and thick stratum corneum (SC), respectively. To fit the reflection data, a homogeneous unilayer and three multilayer skin models were tested. Skin permittivity in the mm-wave frequency range resulted from the permittivity of cutaneous free water which was described by the Debye equation. The permittivity increment found from fitting to the experimental data was used for determination of the complex permittivity and water content of skin layers. Our approach, first tested in pure water and gelatin gels with different water contents, gave good agreement with literature data. The homogeneous skin model fitted the forearm data well. Permittivity of the forearm skin obtained with this model was close to the skin permittivity reported by others. To fit reflection from the palmar skin with a thick SC, a skin model containing at least two layers was required. Multilayer models provided better fitting to both the forearm and palmar skin reflection data. The fitting parameters obtained with different models were consistent with each other.

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Section: Introductionmentioning

confidence: 99%

Human skin permittivity determined by millimeter wave reflection measurements

Алексеев

Ziskin

2007

Bioelectromagnetics

166

156

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“…Mechanical [27][28][29], electrical [20][21][22][23][24][25][26] and thermal [6,7] properties of keratin have been found to strongly depend on the amount of moisture in the sample and hence it is important to understand the exact nature of bound water in keratin. Recently keratin has also been proposed for use as a biomaterial [30] and physical and chemical stability of biopharmaceuticals is highly dependent on their interactions with the low levels of water, which is generally present in their lyophilized preparations [31].…”

Section: Introductionmentioning

confidence: 99%

“…The nature of keratin has been the subject of numerous investigations involving host of experimental techniques such as mechanical properties [4], dynamic mechanical loss [5], differential scanning calorimetry (DSC) [6,7], conventional and advanced microscopic techniques like optical microscopy, scanning electron microscopy [8], transmission electron microscopy and atomic force microscopy [9], spectroscopic techniques like nuclear magnetic resonance (NMR) [10], Fourier transform infrared (FTIR) and Raman spectroscopy [11,12], NIR spectroscopy [13], ellipsometry [14,15], structural techniques like conventional X-ray diffraction [16,17] and that employing synchrotron radiation [18,19] and various electric and dielectric techniques [20][21][22][23][24][25][26]. Mechanical [27][28][29], electrical [20][21][22][23][24][25][26] and thermal [6,7] properties of keratin have been found to strongly depend on the amount of moisture in the sample and hence it is important to understand the exact nature of bound water in keratin.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent dielectric properties of slightly hydrated horn keratin

Rizvi

Khan

2008

International Journal of Biological Macromolecules

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“…31 40 and time-domain reflectometry. 41 These methods differ in their choice of frequency, and whether they use electrodes or antennas, but fundamentally use the same principle. Advantages of using radiofrequency waves to measure edema include water specificity, the potential for the device to be handheld, and the lack of ionizing radiation.…”

Section: Edema Assessmentmentioning

confidence: 99%

Subepidermal moisture surrounding pressure ulcers in persons with a spinal cord injury: A pilot study

Harrow¹,

Mayrovitz

2014

The Journal of Spinal Cord Medicine

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Objective: Characterization of a non-invasive method of quantifying subepidermal moisture (SEM) surrounding stages III and IV pressure ulcers (PrUs) in spinal cord injury (SCI). Design: Prospective, single-visit, single-rater, observational study, using repeated-measures analysis. Method: Setting-inpatient units of one VA SCI Center. Participants: Convenience sample of 16 subjects with SCI with stage III or IV PrUs over sacrum or ischium. Interventions: Measurement with the MoistureMeter-D, a hand-held device using 300 MHz electromagnetic waves. Outcome measures: Dielectric constant, a dimensionless number which increases with the moisture content. Each subject had a PrU site and a control site. Measurements were made at each site, on intact skin, at four points spaced angularly around the site, in triplicate. Results: (1) Short-term, single-rater relative error was 2.5%. (2) Order effect: first readings were higher than second readings in 55 of 64 measurement sets. Order effect was significant for control sites (P < 0.0001) but not for PrU sites. (3) Angular effect: SEM varied by angle at the PrU sites (P < 0.01); 12 o'clock position the highest and 6 o'clock the lowest. (4) Ability to differentiate PrUs from intact skin: SEM at PrU sites was greater by 9.0% than control sites (P < 0.05). (5) Site effect: SEM was higher at sacral locations than ischial at control sites by 20% (P < 0.005). Conclusions: SEM differentiates PrUs from intact skin. Future study designs must take into account order, angular, and site effects on this measure. This information will inform designers of future studies of SEM in healing of PrUs.

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In VivoDielectric Analysis of Free Water Content of Biomaterials by Time Domain Reflectometry

Cited by 32 publications

References 28 publications

Human skin permittivity determined by millimeter wave reflection measurements

Human skin permittivity determined by millimeter wave reflection measurements

Temperature-dependent dielectric properties of slightly hydrated horn keratin

Subepidermal moisture surrounding pressure ulcers in persons with a spinal cord injury: A pilot study

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