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by A. Rouane
2003, Physiological Measurement
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1997, European Biophysics Journal
2005, Bioelectromagnetics
The impedance spectroscopy technique (IST) was used for studying the effect of a 0.5 T magnetic field on the electrical properties of whole human blood. A Solartron SI 1260 spectrometer was used to measure the impedance spectra of magnetic field exposed blood samples compared to non-exposed samples. An equivalent electrical circuit model, consisting in a resistance Rs in series with a parallel circuit formed by a constant phase element (CPE) and another resistance Rp, is proposed to fit the data in both cases. The experiment used 3 ml human blood samples from 160 healthy donors. A Wilcoxon matched pairs statistical test was applied to the data. The data analysis seems to show a statistically significant increase of the values of resistance Rp (Z = 5.06, P < 0.001) and capacitance CT (Z = 3.32, P < 0.001) of the blood exposed to magnetic field, by approximately 10.4% and 1.9%, respectively. Bioelectromagnetics 26:564–570, 2005. © 2005 Wiley-Liss, Inc.
2015, A Study of Dielectric Properties of Proteinuria between 0.2 GHz and 50 GHz
This paper investigates the dielectric properties of urine in normal subjects and subjects with chronic kidney disease (CKD) at microwave frequency of between 0.2 GHz and 50 GHz. The measurements were conducted using an open-ended coaxial probe at room temperature (25 degrees C), at 30 degrees C and at human body temperature (37 degrees C). There were statistically significant differences in the dielectric properties of the CKD subjects compared to those of the normal subjects. Statistically significant differences in dielectric properties were observed across the temperatures for normal subjects and CKD subjects. Pearson correlation test showed the significant correlation between proteinuria and dielectric properties. The experimental data closely matched the single-pole Debye model. The relaxation dispersion and relaxation time increased with the proteinuria level, while decreasing with the temperature. As for static conductivity, it increased with proteinuria level and temperature. Link to Full-Text Articles : http://www.ncbi.nlm.nih.gov/pubmed/26066351 http://www.plosone.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pone.0130011&representation=PDF
2005, IEEE Transactions on Biomedical Engineering
2009, Bioelectromagnetics
In this article, we propose and validate theoretical and experimental methods to quantitatively assess the Debye dielectric model of membrane lipid bi-layers. This consists of two steps: permittivity measurements of biological solutions (liposomes), and estimation of the model parameters by inverse application of the Effective Medium Theory. The measurements are conducted in the frequency domain between 100 MHz and 2 GHz using a modified coaxial connector, at the temperatures of 27 and 30 °C. Estimations have been performed using a three-layered model based on the Maxwell–Wagner formulation. Debye parameters (mean value ± standard error) found from fitting experimental data are: εs = 11.69 ± 0.09, ε∞ = 4.00 ± 0.07, frelax = 179.85 ± 6.20 MHz and εs = (1.1 ± 0.1) × 10−7 S/m. This model can be used in microdosimetric studies aiming to precisely determine the E-field distribution in a biological target down to the single cell level. In this context the use of an accurate membrane dielectric model, valid through a wide frequency range, is particularly appropriate. Bioelectromagnetics 30:286–298, 2009. © 2009 Wiley-Liss, Inc.
2007, Bioelectrochemistry
Progress In Electromagnetics Research Letters
This paper presents a numerical study of the thermal effects induced by a commercial RFID antenna in vials filled with blood plasma. The antenna is located under a conveyor belt which transports cardboard boxes bearing test tubes or pooling bottles. Part of the energy used to read the RFID tags penetrates into the vials and heats the plasma. Our aim is to assess if the RFID technology can alter the quality of the blood plasma by increasing excessively its temperature. To do so, we first compute the specific absorption rate inside the vials with the finite element method. Then, assuming that no heat dissipation process is present, we estimate the number of continuous reading cycles required to increase the plasma temperature 0.1 • C in the worst-case scenario.
1996, Physics in Medicine and Biology
The dielectric properties of tissues have been extracted from the literature of the past five decades and presented in a graphical format. The purpose is to assess the current state of knowledge, expose the gaps there are and provide a basis for the evaluation and analysis of corresponding data from an on-going measurement programme.
2005, cell
The main objective of this work is to evaluate a cell for dielectric properties measurement of biological material. A prototype was designed based on Titanium electrodes connected to an LRC meter. The prototype was designed for applications from ...
1996, Physics in Medicine and Biology
A parametric model was developed to describe the variation of dielectric properties of tissues as a function of frequency. The experimental spectrum from 10 Hz to 100 GHz was modelled with four dispersion regions. The development of the model was based on recently acquired data, complemented by data surveyed from the literature. The purpose is to enable the prediction of dielectric data that are in line with those contained in the vast body of literature on the subject. The analysis was carried out on a Microsoft Excel spreadsheet. Parameters are given for 17 tissue types.
1996, Physics in Medicine and Biology
Three experimental techniques based on automatic swept-frequency network and impedance analysers were used to measure the dielectric properties of tissue in the frequency range 10 Hz to 20 GHz. The technique used in conjunction with the impedance analyser is described. Results are given for a number of human and animal tissues, at body temperature, across the frequency range, demonstrating that good agreement was achieved between measurements using the three pieces of equipment. Moreover, the measured values fall well within the body of corresponding literature data.
1998, Biophysical Journal
Dielectric properties of suspended cells are explored by analysis of the frequency-dependent response to electric fields. Impedance (IMP) registers the electric response, and kinetic phenomena like orientation, translation, deformation, or rotation can also be analyzed. All responses can generally be described by a unified theory. This is demonstrated by an RC model for the structural polarizations of biological cells, allowing intuitive comparison of the IMP, dielectrophoresis (DP), and electrorotation (ER) methods. For derivations, cells of prismatic geometry embedded in elementary cubes formed by the external solution were assumed. All geometrical constituents of the model were described by parallel circuits of a capacitor and a resistor. The IMP of the suspension is given by a meshwork of elementary cubes. Each elementary cube was modeled by two branches describing the current flow through and around the cell. To model DP and ER, the external branch was subdivided to obtain a reference potential. Real and imaginary parts of the potential difference of the cell surface and the reference reflect the frequency behavior of DP and ER. The scheme resembles an unbalanced Wheatstone bridge, in which IMP measures the current-voltage behavior of the feed signal and DP and ER are the measuring signal. Model predictions were consistent with IMP, DP, and ER experiments on human red cells, as well as with the frequency dependence of field-induced hemolysis. The influential radius concept is proposed, which allows easy derivation of simplified equations for the characteristic properties of a spherical single-shell model on the basis of the RC model.
2007, Physics in Medicine and Biology
This paper concerns a theoretical and electrical modelling of interdigital sensor in a wide band frequency. A theoretical approach is proposed to optimize the use of the sensor for bioimpedance spectroscopy. CoventorWare software was used to modelize in three dimensions the interdigital sensor system for measuring electrical impedance of biological medium. Complete system simulation by Finite element method (FEM) was used for sensor sensitivity optimization. The influence of geometric parameters (number of fingers, width of the electrodes, …), on the impedance spectroscopy of biological medium was studied. A high level description of the sensor and the biological medium was also developed under VHDL-AMS with SystemVision software from mentor graphics. The simulation results are compared with measurements obtained with a true interdigitated sensor illustrating a good correlation. This shows that even the theoretical model is simple, it remains very effective.
The present work aims are to study the radiation effects on the red blood cell membrane from three different but correlated properties: electrical, mechanical and chemical, and to derive useful parameters for the evaluation of radiation effects. AC conductivity of cell suspension was measured in the frequency range 40 kHz to 5 MHz, the osmotic fragility of the membrane and solubilization of the membrane by detergent were also measured. Adult male rats were exposed to 1, 2.5, 3.5, 5, 7 and 9 Gy gamma radiation from Cs137 source. The results showed decrease in the AC conductivity, average osmotic fragility and average membrane solubilization. The effect of radiation on the red blood cell membrane was discussed.
1984
1984, IEEE Transactions on Electrical Insulation
2011
It has been demonstrated that the erythrocytes (RBCs) oscillate during their tank-treading motion with high-frequency oscillations. This oscillatory motion drastically affects the dielectric and electrical properties of RBCs. Moreover, the glucose level in blood affects the electrical and dielectric properties of blood. It has been, also, shown that the frequency of these oscillations exponentially decrease from 1.2 MHz down to 0.85 MHz with variation of glucose level from 85 mg∕dL up to 346.1 mg∕dL. It is expected that these oscillations strongly affect the general physiological properties of blood and would stimulate the curiosity of scientists and bioengineers to present new, more efficient, rapid, safe and viable diagnostic and∕or therapeutic methods for blood disorders; in particular diabetes.
1986, Biophysical Journal
2000, Annals of Biomedical Engineering
2009, Physics in Medicine and Biology
A two-pronged approach, review and measurement, has been adopted to characterize the conductivity of tissues at frequencies below 1 MHz. The review covers data published in the last decade and earlier data not included in recent reviews. The measurements were carried out on pig tissue, in vivo, and pig body fluids in vitro. Conductivity data have been obtained for skeletal and myocardial muscle, liver, skull, fat, lung and body fluids (blood, bile, CSF and urine). A critical analysis of the data highlights their usefulness and limitations and enables suggestions to be made for measuring the electrical properties of tissues.
2009, Bioelectrochemistry
2010, Bioelectrochemistry
2011, Process Biochemistry
2009, Progress In Electromagnetics Research B
1981, Bioelectromagnetics
Diabetes mellitus is a disease in which the body does not produce enough, or properly respond to, insulin, a hormone produced in the pancreas. The rheological and electrical properties of red blood cells in the patients with diabetes have been studied in order to assess the complications of the disease. There was an increase in the viscosity and the yield stress of diabetic erythrocyte comparing to the normal. These may lead to the increase in the aggregation and decrease in deformability of red blood cells due to reducing the negative surface electric charge. The rheological disorders could lead to microcirculation problems. On the other hand, the relative permittivity, dielectric loss, and AC conductivity of diabetic erythrocytes increased significantly compared to the control. This is due to the toxic effects of glucose on erythrocytes which lead to restructuring of erythrocytes membranes. The high glucose value leads to imbalance of electrolytes in red blood cell membrane and th...
1995, Colloids and Surfaces B: Biointerfaces
2008, Journal of Physics D: Applied Physics
2005, IEEE Transactions on Biomedical Engineering
In a previous paper, a new dielectric technique was used to estimate hematocrit (HTC) in extracorporeal blood circulation systems, independently of plasma conductivity or osmolarity. Although many impedance techniques have been formerly proposed in the literature, none has been evaluated against plasma conductivity and osmolarity. Herein, we estimate HTC based on permittivity changes and also with other four techniques found
Assessment of the dielectric properties of red blood cells requires several steps for preparation and isolation from whole blood. These steps may result in changes in the cells properties, and they are time consuming. The present study aims to compare the properties of both whole blood and isolated red blood cells and the effect of gamma radiation on these properties. Adult male rats were exposed to 1, 3.5 and 7 Gy as single dose, from Cs-137 source. The dielectric properties studies, in the frequency range 40 kHz to 5 MHz, and light scattering studies for suspensions of whole blood and isolated red blood cells from the same groups were performed. The obtained results showed that whole blood and red blood cells suspensions followed the same trend in their response to radiation, which suggests the possibility of using whole blood suspension for the evaluation of the red blood cells properties.
2009, The Journal of Physical Chemistry B
A B S T R A C T For ellipsoidal objects, the complex conductivity of the suspension depends on the objects' axis ratio and orientation. It can be described by analytical equations that were derived by combining the influential radius approach with the mixing equation of Maxwell and Wagner. Here, we consider conductive or insulating homogeneous spheroids, with their symmetry axes being oriented in parallel, in perpendicular or at random with respect to the external field. Considerations show that the field-induced orientations of both nonconductive and conductive objects will result in a reduction of the suspension's impedance and an increased dissipation of electrical energy.
1999, Biophysical Journal
2007
Bunthawin, S., Wanichapichart, P. and Gimsa, J. An investigation of dielectric properties of biological cells using RC-model This paper proposes a method for estimating cell dielectric properties of a spherical triple shell and ellipsoidal shell models from the Laplace and RC approaches. With a combination of various theoretical parameters such as cell dielectrophoretic velocity, angular velocity of electro-rotation (ER) and two critical frequencies of dielectrophoresis (DEP), these approaches will improve the predictability of the dielectric properties. The calibration of the model parameters to these experimental data results in estimations of the cellís electrical properties depending on the geometric structure of the assumed model.
1982, Bioelectromagnetics
2010, Applied Radiation and Isotopes
2011, Journal of Electrical Bioimpedance
2013, Computational and Mathematical Methods in Medicine
1983, IEE Proceedings A Physical Science, Measurement and Instrumentation, Management and Education, Reviews
2010, Physical Review E