Dielectric properties of ocular tissues at 37 degrees C

Gabriel, Camelia; Sheppard, R J; Grant, E H

doi:10.1088/0031-9155/28/1/004

Cited by 64 publications

(41 citation statements)

References 15 publications

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“…Above 100MHz the dielectric properties of tissues are consistent with those expected for a suspension of low conductivity particles (cells) in an aqueous electrolyte and the distinction between tissue types becomes lost [52]. A less pronounced lowering of the water relaxation frequency was observed for ocular tissues [53]. The relaxation frequency of normal bulk water at 37°C is 25 GHz, whereas retina (89% water content) exhibited a relaxation frequency of around 2 GHz, and for the lens nucleus (65% water) this was reduced to around 9GHz.…”

Section: δ -Dispersionssupporting

confidence: 69%

Modeling of Dielectric Permittivity of the Erythrocytes Membrane as a Three-Layer Model

Batyuk¹,

Kizilova²

2018

Development Trends in Medical Science and Practice: The Experience of Countries of Eastern Europe and Prospects of Ukraine

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Abstract. The dielectric theories which used for applications of dielectric spectroscopy to investigate heterogeneous systems, such as particle suspensions, membranes, and tissue are described in this article. The dielectric constant ′ ε , the loss ′′ ε , and the conductivity σ of substances in a broad frequency range (1 Hz to 10 11 Hz), with for using a combination of different method of dielectric spectroscopy applied to identical samples was described. In the present work, we analyze the dispersion regions, commonly found in biological substances and tissue, usually as termed as α , β , δ and γ -dispersions. The nature of the dispersion caused by the membrane of RBCs in the radio frequency spectrum of the dielectric properties of blood which often is ascribed to the motion of bound water molecules is not yet fully understood. Dielectric properties of RBS membrane have been studied by means of the spheroidal model, where the three shells correspond to the double lipid bilayer and the spectrin network of the inner membrane, respectively. Based on the Maxwell-Wagner model and takes into account the morphological parameters of RBS membranes of cells using appropriate approximations the some simple relations was derived. In discussing the dielectric properties of RBS membrane was considered the mathematical model which accurately fit the experimental observations. Such models have obvious applications when characterizing the data and testing it against possible physical theories. Modeling of dielectric permittivity of the erythrocytes membrane as… IntroductionThe blood represents of heterogeneous material containing water, dissolved organic molecules, macromolecules, ions and soluble matter. The constituents of the blood are highly organized in cellular and subcellular structures forming macroscopic elements. The presence of ions in the blood plays an important role in the interaction with an electric field, providing means for ionic conduction and polarization effects. The ionic charge drift creates conduction currents and as knows as initiates polarization mechanisms through charge accumulation at structural interfaces, which occur at various organizational levels of membranes of cells of blood. Their dielectric properties will thus reflect contributions to the polarization from both structure and composition [1]. A common way to describe dielectric properties of cell of human blood or tissue between 1 Hz and 50 GHz is to fit ColeCole or Cole-Cole-type relaxation models to measurement data [2][3][4][5]. The measurement of dielectric properties of blood is known to be of importance for diagnosis of diseases [6][7][8][9][10][11]. Early studies of dielectric properties of the human erythrocytes are connecting with alternating current in the frequency domain were pioneered at the beginning of this century [12][13][14][15][16]. The frequency dependence of the dielectric properties of the RBC in suspension has been investigated by many scientists [17][18][19][20][21][22][23][24][25][26][27][28]. In the simplest model...

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Section: δ -Dispersionssupporting

confidence: 69%

Modeling of Dielectric Permittivity of the Erythrocytes Membrane as a Three-Layer Model

Batyuk¹,

Kizilova²

2018

Development Trends in Medical Science and Practice: The Experience of Countries of Eastern Europe and Prospects of Ukraine

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“…This small depth helps to reduce biological attenuation effects while still allowing for pressure measurement feasibility. Rabbit ocular tissue was used for measuring dielectric properties from 10 MHz -10 GHz in [1]. From this data, we estimated the dielectric properties of sclera tissue at 2.4 GHz to have a relative permittivity (ε') of 50, a dielectric loss (ε'') of 19, and a conductivity (σ) of 3 Ω -1 m -1 .…”

Section: Iitransocular Attenuationmentioning

confidence: 99%

“…Using known values, the power reduction effects of the ocular tissue can be calculated and predicted. Using the Matlab program along with the dielectric properties of rabbit cornea tissue from [1], the calculated power reduction through a 1 mm depth at 2.4 GHz is -4.5 dB.…”

Section: Iitransocular Attenuationmentioning

confidence: 99%

Miniature antenna for RF telemetry through ocular tissue

Chow

Yang

Chlebowski

et al. 2008

2008 IEEE MTT-S International Microwave Symposium Digest

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In this study, we experiment with the feasibility of wireless telemetry using a miniature wireless system fully implanted within the eye. Of significant importance is the ability to transmit signals from miniature packaged systems without undue absorption of signals. Theoretical calculations found the attenuation through the eye to be -4.5 dB in the far field region, indicating that low power transmission systems can be implemented. Through the use of multilayer integrated Low Temperature Co-fired Ceramics (LTCC) packages, telemetry data through the eye was collected and compared to transmission in free space. In animal studies done using porcine eyes, we were able to successfully transmit and receive from the implanted device in the near field and far field regions measuring 2 dB and 6 dB of power reduction respectively.Index Terms -Biomedical applications of EM radiation, biosensor, biomedical telemetry, microstrip antennas, LTCC package.

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“…In order to precisely model the configuration of eyes which comprise ultra-thin millimetre-scale membrane structures, a resolution of 0.2 mm is proposed. Table 1 [24][25][26][27][28][29][30][31]35] presents the dielectric properties at 0.915 GHz and densities assigned to different biological materials for the following calculation. ε r and σ represent the relative dielectric constant and conductivity, respectively.…”

Section: Head Modelmentioning

confidence: 99%

Evaluation of Microwave Microdosimetry for Human Eyes With Glasses Exposed to Wireless Eyewear Devices at Phone Call State

Lan¹,

Hong²,

Liang³

et al. 2018

PIER M

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Abstract-This paper evaluates the effect of glasses on the Specific Absorption Rate (SAR) and the absorbed power in the human head exposed to microwave from wireless eyewear device at phone call state. Due to the sensitivity of eyes to microwave, this paper mainly concentrates on the SAR and the absorbed power in ocular tissues. The calculated results indicate that wearing glasses can obviously increase the maximal SAR and the absorbed power in ocular tissues. Glasses has almost doubled the maximal SAR in ocular tissues. The absorbed power with glasses is about 3.1-4.5 times as big as that without glasses. Furthermore, we find that the maximal SAR and absorbed power are sensitive to the width of glass leg and the thickness of spectacle lens, while variation trends with the varying glasses size are quite different. Hypermyopia patient might suffer from higher risk of getting the oculopathy due to the larger SAR caused by the thicker spectacle lens. In conclusion, wearing glasses may pose higher health risk on eyes of wireless eyewear device user. This paper would provide valuable reference data for the future evaluation of microwave biological effect on eyes.

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Dielectric properties of ocular tissues at 37 degrees C

Cited by 64 publications

References 15 publications

Modeling of Dielectric Permittivity of the Erythrocytes Membrane as a Three-Layer Model

Modeling of Dielectric Permittivity of the Erythrocytes Membrane as a Three-Layer Model

Miniature antenna for RF telemetry through ocular tissue

Evaluation of Microwave Microdosimetry for Human Eyes With Glasses Exposed to Wireless Eyewear Devices at Phone Call State

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