Electrical properties of lens material at microwave frequencies

Dawkins, A W J; Cabriel, Clément; Sheppard, R J; Grant, E H

doi:10.1088/0031-9155/26/1/002

Cited by 22 publications

(6 citation statements)

References 19 publications

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“…Moreover this difference is increasing as the frequency decreases. The rapid fall in relative permittivity (e') with frequency up to around 100 MHz is known (Schwan & Foster, 1980;Grant et al, 1978) to be a property of the cell membranes and has been observed in other biological tissues such as brain (Nightingale et al, 1980) and lens (Dawkins et al, 1981a). For all tissues, including the mouse muscle investigated in the present work, the data between about 50 and about 500 MHz correspond to the high frequency tail of the ^-dispersion.…”

Section: Discussionmentioning

confidence: 99%

The dielectric properties of normal and tumour mouse tissue between 50 MHz and 10 GHz

Rogers¹,

Sheppard²,

Grant³

et al. 1983

BJR

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Microwaves are currently being investigated as a method of inducing hyperthermia. Values of the relative permittivity and conductivity of mouse muscle and tumour tissues over the frequency range 50 MHz to 10 GHz at a temperature of 37 degrees C are reported. The data were obtained by using an on-line computer-based time-domain spectrometer. The tumour tissues were the RIF/1 and KHT fibrosarcomas sited in the hind leg muscle of C3H mice. A significant difference in the relative permittivity between the normal and tumour tissue was shown to exist at frequencies up to 200 MHz.

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Section: Discussionmentioning

confidence: 99%

The dielectric properties of normal and tumour mouse tissue between 50 MHz and 10 GHz

Rogers¹,

Sheppard²,

Grant³

et al. 1983

BJR

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“…The model parameters for porcine cornea from Table 1 are used to provide comparison with a recent set of cornea data [34] measured and reported for three age-groups of pigs over the 0.4-10 GHz frequency range. In accordance with the measurement procedures [35] which correspond to the parallel electric field polarization for the cornea, comparison is presented for ε cor in Figure 4 and in the rest of the paper. The model shows agreement with the experimental data within the usual experimental tolerance of 20%.…”

Section: Resultsmentioning

confidence: 99%

A Theoretical Model for the Frequency-Dependent Dielectric Properties of Corneal Tissue at Microwave Frequencies

Saviz¹,

Faraji‐Dana²

2013

PIER

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Abstract-This paper presents a structured model of the dielectric properties of the corneal tissue at microwave frequencies, based on the fine structure and chemical composition of its constituents. This is accomplished by appropriately combining the known properties of tissue substructures using mixing rules, in order to obtain the effective macroscopic properties of the medium. The presented approach is multi-scale: it begins from the microscopic scale and derives the macroscopic properties after several scale-steps. The predictions of the model agree with the existing measured data in the literature. Verification and analysis of the model sensitivity to input parameters have been presented. The model is expected to find application in non-invasive medical sensing where it can relate dielectric response to pathological structural changes in the tissue. The model is also useful for the prediction of dielectric properties for highfrequency computational dosimetry, and for understanding the physical mechanisms behind the macroscopic dielectric behaviour in general.

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“…In previous publications (Dawkins et al 1981a, Gabriel et a1 1983 measurements have been reported on the dielectric parameters of various ocular tissues at 37 "C. In the present work dielectric data on three tissues-retina, lens cortex and lens nucleus-are presented over a temperature range. It was hoped that varying the temperature would provide additional information which would further our research concerned with studying the nature of water in biological material.…”

Section: Introductionmentioning

confidence: 79%

Dielectric properties of ocular tissues in the supercooled and frozen states

Gabriel¹,

Grant²

1985

Phys. Med. Biol.

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Values of the relative permittivity and conductivity of the rabbit retina and lens have been measured between 10 MHz and 10 GHz over the temperature range 20 to -20 degrees C. As the temperature was lowered from 20 degrees C the dielectric parameters changed smoothly until -9 degrees C where freezing occurred. At this temperature a sharp transition was observed in both conductivity and relative permittivity, the latter falling to a value of below 10 over most of the frequency range. Analysis shows that this is due to the unfreezable water, from which a value of lens hydration is calculated. This value agrees with that obtained previously at 37 degrees C using conventional dielectric mixture theory, but the associated margin of error is much smaller.

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Electrical properties of lens material at microwave frequencies

Cited by 22 publications

References 19 publications

The dielectric properties of normal and tumour mouse tissue between 50 MHz and 10 GHz

The dielectric properties of normal and tumour mouse tissue between 50 MHz and 10 GHz

A Theoretical Model for the Frequency-Dependent Dielectric Properties of Corneal Tissue at Microwave Frequencies

Dielectric properties of ocular tissues in the supercooled and frozen states

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