Journal articles: 'Dielectric properties of human tissues'

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Yilmaz, Tuba, and Fatma Ates Alkan. "In Vivo Dielectric Properties of Healthy and Benign Rat Mammary Tissues from 500 MHz to 18 GHz." Sensors 20, no. 8 (April 14, 2020): 2214. http://dx.doi.org/10.3390/s20082214.

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This work investigates the in vivo dielectric properties of healthy and benign rat mammary tissues in an attempt to expand the dielectric property knowledge of animal models. The outcomes of this study can enable testing of microwave medical technologies on animal models and interpretation of tissue alteration-dependent in vivo dielectric properties of mammary tissues. Towards this end, in vivo dielectric properties of healthy rat mammary tissues and chemically induced benign rat mammary tumors including low-grade adenosis, sclerosing adenosis, and adenosis were collected with open-ended coaxial probes from 500 MHz to 18 GHz. The in vivo measurements revealed that the dielectric properties of benign rat mammary tumors are higher than the healthy rat mammary tissues by 9.3% to 35.5% and 19.6% to 48.7% for relative permittivity and conductivity, respectively. Furthermore, to our surprise, we found that the grade of the benign tissue affects the dielectric properties for this study. Finally, a comparison with ex vivo healthy human mammary tissue dielectric properties revealed that the healthy rat mammary tissues best replicate the dielectric properties of healthy medium density human samples.

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Surowiec, A., S. S. Stuchly, L. Eidus, and A. Swarup. "In vitro dielectric properties of human tissues at radiofrequencies." Physics in Medicine and Biology 32, no. 5 (May 1, 1987): 615–21. http://dx.doi.org/10.1088/0031-9155/32/5/007.

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Werber, D., A. Schwentner, and E. M. Biebl. "Investigation of RF transmission properties of human tissues." Advances in Radio Science 4 (September 6, 2006): 357–60. http://dx.doi.org/10.5194/ars-4-357-2006.

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Abstract. RF transmission properties of human tissues were investigated in the frequency range from 50 MHz to 1 GHz. This work was motivated by the increasing interest in communication links between medically active implants and external interrogator units. We investigated theoretically and experimentally the transmission loss between an implant and an external interrogator unit. We assumed that due to the size of the implant a maximum area of only 1 cm2 is available for the printed circuit antenna. The size of the external interrogator antenna is less restricted. The maximum depth of the implant beneath the surface of the body was assumed to be 10 cm. For the simulations we took the dielectric properties of skin, fat and muscle as published in the literature. For the measurements, an artificial muscle dielectric proposed in the literature was used consisting mainly of a mixture of water, sugar and salt. In simulation and measurements the reactive part of the impedance of the antennas was compensated numerically. In simulations and measurements we obtained a transmission loss between 30 dB around 100 MHz and 65 dB around 900 MHz.

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Hahn, Camerin, and Sima Noghanian. "Heterogeneous Breast Phantom Development for Microwave Imaging Using Regression Models." International Journal of Biomedical Imaging 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/803607.

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As new algorithms for microwave imaging emerge, it is important to have standard accurate benchmarking tests. Currently, most researchers use homogeneous phantoms for testing new algorithms. These simple structures lack the heterogeneity of the dielectric properties of human tissue and are inadequate for testing these algorithms for medical imaging. To adequately test breast microwave imaging algorithms, the phantom has to resemble different breast tissues physically and in terms of dielectric properties. We propose a systematic approach in designing phantoms that not only have dielectric properties close to breast tissues but also can be easily shaped to realistic physical models. The approach is based on regression model to match phantom's dielectric properties with the breast tissue dielectric properties found in Lazebnik et al. (2007). However, the methodology proposed here can be used to create phantoms for any tissue type as long asex vivo,in vitro, orin vivotissue dielectric properties are measured and available. Therefore, using this method, accurate benchmarking phantoms for testing emerging microwave imaging algorithms can be developed.

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Lu, Yongjun, Hongming Cui, Jue Yu, and Satoru Mashimo. "Dielectric properties of human fetal organ tissues at radio frequencies." Bioelectromagnetics 17, no. 5 (1996): 425–26. http://dx.doi.org/10.1002/(sici)1521-186x(1996)17:5<425::aid-bem10>3.0.co;2-l.

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Martinsen, Ø. G., S. Grimnes, and E. S. Kongshaug. "Dielectric properties of some keratinised tissues. Part 2: Human hair." Medical & Biological Engineering & Computing 35, no. 3 (May 1997): 177–80. http://dx.doi.org/10.1007/bf02530034.

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Maniakova, Eva, and Dagmar Faktorova. "MEASURING THE DIELECTRIC PROPERTIES OF TUMOR AND BREAST PHANTOMS USED IN THE MICROWAVE FREQUENCY RANGE." CBU International Conference Proceedings 4 (September 16, 2016): 647–51. http://dx.doi.org/10.12955/cbup.v4.826.

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INTRODUCTION: This article deals with measurement of dielectric properties (relative permittivity and conductivity) of phantoms, specifically a tumor phantom and a breast phantom. We focused on the waveguide and resonance methods for the measurement of dielectric properties. The article describes the principle of these methods, and also the production process of a breast phantom and a tumor phantom. These phantoms can be used for measurements in the microwave frequency range, 8–12 GHz.OBJECTIVE: The study’s objective was to design a tumor phantom and a breast phantom, and to measure their dielectric properties. These properties must simulate human tissue.METHODS: To measure dielectric properties of human tissue, phantoms were designed using the waveguide Hippel`s method and the resonance method with a cavity resonator.RESULTS: The aim of this work was to create the phantoms that would have properties comparable to those of real tissues. Results of measurement are shown as frequency dependence of relative permittivity and conductivity for breast, breast phantom, tumor, and tumor phantom.

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Motrescu, V. C., and U. van Rienen. "Computation of currents induced by ELF electric fields in anisotropic human tissues using the Finite Integration Technique (FIT)." Advances in Radio Science 3 (May 12, 2005): 227–31. http://dx.doi.org/10.5194/ars-3-227-2005.

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Abstract. In the recent years, the task of estimating the currents induced within the human body by environmental electromagnetic fields has received increased attention from scientists around the world. While important progress was made in this direction, the unpredictable behaviour of living biological tissue made it difficult to quantify its reaction to electromagnetic fields and has kept the problem open. A successful alternative to the very difficult one of performing measurements is that of computing the fields within a human body model using numerical methods implemented in a software code. One of the difficulties is represented by the fact that some tissue types exhibit an anisotropic character with respect to their dielectric properties. Our work consists of computing currents induced by extremely low frequency (ELF) electric fields in anisotropic muscle tissues using in this respect, a human body model extended with muscle fibre orientations as well as an extended version of the Finite Integration Technique (FIT) able to compute fully anisotropic dielectric properties.

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Yan, L. P., K. M. Huang, and C. J. Liu. "A Noninvasive Method for Determining Dielectric Properties of Layered Tissues on Human Back." Journal of Electromagnetic Waves and Applications 21, no. 13 (January 1, 2007): 1829–43. http://dx.doi.org/10.1163/156939307781890978.

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Garrett, John, and Elise Fear. "Stable and Flexible Materials to Mimic the Dielectric Properties of Human Soft Tissues." IEEE Antennas and Wireless Propagation Letters 13 (2014): 599–602. http://dx.doi.org/10.1109/lawp.2014.2312925.

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Munawar, Awais, Zartasha Mustansar, Ahmed E. Nadeem, and Mahmood Akhtar. "AN INVESTIGATION INTO ELECTROMAGNETIC BASED IMPEDANCE TOMOGRAPHY USING REALISTIC HUMAN HEAD MODEL." International Journal of Pharmacy and Pharmaceutical Sciences 8, no. 2 (September 17, 2016): 35. http://dx.doi.org/10.22159/ijpps.2016v8s2.15217.

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<p class="lead">The objective of this research is to investigate the feasibility of Electromagnetic based Impedance Tomography (EMIT) for brain stroke detection, localization and classification. Electromagnetic based Impedance Tomography employing microwave imaging technique is an emerging brain stroke diagnostic modality. It relies on the significant contrast between dielectric properties of the normal and abnormal brain tissues. To study the interaction between micro-wave signals and head tissues, the simulations are performed using a geometrically simple 3-D ellipsoid head model with emulated stroke. Finite Element numerical technique is adopted to find the solution of Maxwell’s equations to measure the transmitted and backscattered signals in forward problem. Contrast Source Inversion technique is proposed to solve the inverse scattering problem and reconstruct brain images based on calculated dielectric profiles. Detailed analysis is performed to determine the safety limits of transmitted signals to minimize ionizing effects while ensuring maximum penetration. The simulations verify the inhomogeneous and frequency-dispersive behavior of brain tissue’s dielectric properties. The solution of the forward problem demonstrates the microwave signals scattering by the multilayer structure of the head model, duly validated by analytical results. The scattering phenomena can be fully capitalized by image reconstruction algorithm to obtain brain images and detect stroke presence. The initial results obtained in this research and prior work indicates that EMIT-based head imaging system has a potential for rapid stroke detection, classification, and continuous brain monitoring and offers a comparatively cost-effective solution.</p>

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Lu, Y., B. Li, J. Xu, and J. Yu. "Dielectric properties of human glioma and surrounding tissue." International Journal of Hyperthermia 8, no. 6 (January 1992): 755–60. http://dx.doi.org/10.3109/02656739209005023.

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Mumin, Abdul Rashid O., R. Alias, Jiwa Abdullah, Raed A. Abdulhasan, Samsul Haimi Dahlan, and Ariffuddin Joret. "Performance Characteristics of Head-Worn Antenna based on Dielectric Substrate Over WBAN Application." International Journal of Engineering & Technology 7, no. 4.30 (November 30, 2018): 403. http://dx.doi.org/10.14419/ijet.v7i4.30.22345.

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Performance characteristics of head-worn antenna based on dielectric substrate for WBAN application with various dielectric constant for square slot patch antenna are demonstrated in this paper. The impact of Electromagnetic (EM) energy from antenna towards human head and on antenna performance changes due to human head proximity are explored in this paper. The human head exposed to 5.8 GHz on ISM frequency band and radiation pattern, return loss, efficiency, and bandwidth and SAR distribution value performance have been thoroughly explored. However, decreasing the antenna size is a great topic ‎of antenna development, which differentiates antenna performance for a small antenna. Multilayered human head phantom having five layers are constructed based on different tissues and these tissues represent human head parts such as (Skin, fat, Cerebrospinal fluid (CSF), bone and brain), all of each tissues are based on their electromagnetic properties and set at 5.8GHz.The proposed antenna with human head model simulated through (FDTD) using CST and variation of parameters of antenna with MATLAB. Antenna with FR4 substrate produces the highest SAR values while antenna with RT5880 substrate has the lowest SAR value 0.206 W/kg and 0.0784 W/kg at 5.8 GHz frequency exposed for 10g tissue respectively. It can be observed that the radiation pattern shows that the antenna gain with substrate of Rogers RT5880 is increased from front –to-back from 7.1 to 7.29 dB in the free space and on human head respectively. A good agreement between simulation and measurements in free space are obtained. The presented prototype has a potential to work for ISM applications.

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Neira, Luz Maria, R. Owen Mays, James F. Sawicki, Amanda Schulman, Josephine Harter, Lee G. Wilke, Nader Behdad, Barry D. Van Veen, and Susan C. Hagness. "A Pilot Study of the Impact of Microwave Ablation on the Dielectric Properties of Breast Tissue." Sensors 20, no. 19 (October 6, 2020): 5698. http://dx.doi.org/10.3390/s20195698.

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Percutaneous microwave ablation (MWA) is a promising technology for patients with breast cancer, as it may help treat individuals who have less aggressive cancers or do not respond to targeted therapies in the neoadjuvant or pre-surgical setting. In this study, we investigate changes to the microwave dielectric properties of breast tissue that are induced by MWA. While similar changes have been characterized for relatively homogeneous tissues, such as liver, those prior results are not directly translatable to breast tissue because of the extreme tissue heterogeneity present in the breast. This study was motivated, in part by the expectation that the changes in the dielectric properties of the microwave antenna’s operation environment will be impacted by tissue composition of the ablation target, which includes not only the tumor, but also its margins. Accordingly, this target comprises a heterogeneous mix of malignant, healthy glandular, and adipose tissue. Therefore, knowledge of MWA impact on breast dielectric properties is essential for the successful development of MWA systems for breast cancer. We performed ablations in 14 human ex-vivo prophylactic mastectomy specimens from surgeries that were conducted at the UW Hospital and monitored the temperature in the vicinity of the MWA antenna during ablation. After ablation we measured the dielectric properties of the tissue and analyzed the tissue samples to determine both the tissue composition and the extent of damage due to the ablation. We observed that MWA induced cell damage across all tissue compositions, and found that the microwave frequency-dependent relative permittivity and conductivity of damaged tissue are lower than those of healthy tissue, especially for tissue with high fibroglandular content. The results provide information for future developments on breast MWA systems.

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Sinha, Debottam, K. Anwar, K. Kumari, S. Jaishwal, S. Madeshwaran, S. Keshari, D. Rajan Babu, R. Vidya, and Narayanasamy Arunai Nambi Raj. "Studies on the Dielectric Properties of Natural Urinary Stones." Advanced Materials Research 584 (October 2012): 484–88. http://dx.doi.org/10.4028/www.scientific.net/amr.584.484.

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Kidney or gall-bladder stones are solid accretions (crystals) of dissolved minerals in urine or bile juice found inside the kidneys or urethras and gall bladder, with varying size from as small as a grain of sand to as large as a golf ball, the occurrence whose in the human is well known, although its pathogenesis is not well understood. According to literature, a number of biomaterials, such as collagen, blood vessel walls, DNA, RNA etc., are found to possess the property of electrets which is an electric analogue of a permanent magnet having the capability to retain quasipermanently, an induced polarization. In order to understand about the occurrence and the physical properties of stone formation in the human tissues, the study of its electret behaviour and conductivity becomes imperative which implies the fact of indulging in its growth inhibition, if their deposition is identified using scans. Thus, in this paper, in order to understand the mechanism of growth of these nephrolithiasis, we enumerated the electrical behaviour of the stone, by using the XRD (X-Ray Diffraction) analysis after their collection from different patient in and around the region and subsequently the dielectric constant of the stone was interpreted.

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Zhekov, Stanislav Stefanov, Ondrej Franek, and Gert Frolund Pedersen. "Dielectric Properties of Human Hand Tissue for Handheld Devices Testing." IEEE Access 7 (2019): 61949–59. http://dx.doi.org/10.1109/access.2019.2914863.

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Munawar Qureshi, Awais, Zartasha Mustansar, and Samah Mustafa. "Finite-element analysis of microwave scattering from a three-dimensional human head model for brain stroke detection." Royal Society Open Science 5, no. 7 (July 2018): 180319. http://dx.doi.org/10.1098/rsos.180319.

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In this paper, a detailed analysis of microwave (MW) scattering from a three-dimensional (3D) anthropomorphic human head model is presented. It is the first time that the finite-element method (FEM) has been deployed to study the MW scattering phenomenon of a 3D realistic head model for brain stroke detection. A major contribution of this paper is to add anatomically more realistic details to the human head model compared with the literature available to date. Using the MRI database, a 3D numerical head model was developed and segmented into 21 different types through a novel tissue-mapping scheme and a mixed-model approach. The heterogeneous and frequency-dispersive dielectric properties were assigned to brain tissues using the same mapping technique. To mimic the simulation set-up, an eight-elements antenna array around the head model was designed using dipole antennae. Two types of brain stroke (haemorrhagic and ischaemic) at various locations inside the head model were then analysed for possible detection and classification. The transmitted and backscattered signals were calculated by finding out the solution of the Helmholtz wave equation in the frequency domain using the FEM. FE mesh convergence analysis for electric field values and comparison between different types of iterative solver were also performed to obtain error-free results in minimal computational time. At the end, specific absorption rate analysis was conducted to examine the ionization effects of MW signals to a 3D human head model. Through computer simulations, it is foreseen that MW imaging may efficiently be exploited to locate and differentiate two types of brain stroke by detecting abnormal tissues’ dielectric properties. A significant contrast between electric field values of the normal and stroke-affected brain tissues was observed at the stroke location. This is a step towards generating MW scattering information for the development of an efficient image reconstruction algorithm.

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Koyama, Kazunori, Akimasa Hirata, Jianquing Wang, and Osamu Fujiwara. "In-Vivo Time Domain Measurement of Dielectric Properties of Human Body Tissue." IEEJ Transactions on Fundamentals and Materials 130, no. 12 (2010): 1087–91. http://dx.doi.org/10.1541/ieejfms.130.1087.

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Kalra, Anubha, Andrew Lowe, and Gautam Anand. "Bio Phantoms Mimicking the Dielectric and Mechanical Properties of Human Skin Tissue at Low-Frequency Ranges." Modern Applied Science 14, no. 7 (May 22, 2020): 1. http://dx.doi.org/10.5539/mas.v14n7p1.

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Tissue phantoms are widely used as substitute materials for real tissue validation of various newly emerging biomedical technologies such as ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). However, there is no specific recipe for fabricating skin-mimicking phantoms which can mimic both the mechanical and dielectric properties of human skin at lower frequency ranges. The objective of this paper is to present a variety of tissue-mimicking materials for filling this research gap in the lower frequency range from 20 Hz to 300 kHz. The starting point of our experiments is based on the oil-in-gelatin based tissue-mimicking materials (TMMs) that have shown to mimic the dielectric properties of human skin in higher frequency ranges. This paper examines the mechanical and dielectric performance of five major classes of tissue-mimicking materials (1) Oil-in-gelatin, (2) lignin and graphene nanopowder in gelatin, (3) gelatin and distilled water, (4) mixed oil in gelatin and distilled water, and (5) lignin in gelatin and distilled water. Mechanical and electrical testing was performed using compression testing and parallel plate method respectively. The effect of electrode polarization was considered in the measured data and the intrinsic impedance values were found to be following the Cole-Cole equation. The Young's modulus range of all tissue-mimicking materials was within the range of skin.

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Gavazzi, Soraya, Paolo Limone, Giovanni De Rosa, Filippo Molinari, and Giuseppe Vecchi. "Comparison of microwave dielectric properties of human normal, benign and malignant thyroid tissues obtained from surgeries: a preliminary study." Biomedical Physics & Engineering Express 4, no. 4 (May 14, 2018): 047003. http://dx.doi.org/10.1088/2057-1976/aa9f77.

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Campbell, A. M., and D. V. Land. "Dielectric properties of female human breast tissue measured in vitro at 3.2 GHz." Physics in Medicine and Biology 37, no. 1 (January 1, 1992): 193–210. http://dx.doi.org/10.1088/0031-9155/37/1/014.

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Chen, Yifan, Panagiotis Kosmas, and Sylvain Martel. "A Feasibility Study for Microwave Breast Cancer Detection Using Contrast-Agent-Loaded Bacterial Microbots." International Journal of Antennas and Propagation 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/309703.

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We propose a new approach to microwave breast tumor sensing and diagnosis based on the use of biocompatible flagellated magnetotactic bacteria (MTB) adapted to operate in human microvasculature. It has been verified experimentally by Martel et al. that externally generated magnetic gradients could be applied to guide the MTB along preplanned routes inside the human body, and a nanoload could be attached to these bacterial microbots. Motivated by these useful properties, we suggest loading a nanoscale microwave contrast agent such as carbon nanotubes (CNTs) or ferroelectric nanoparticles (FNPs) onto the MTB in order to modify the dielectric properties of tissues near the agent-loaded bacteria. Subsequently, we propose a novel differential microwave imaging (DMI) technique to track simultaneously multiple swarms of MTB microbots injected into the breast. We also present innovative strategies to detect and localize a breast tissue malignancy and estimate its size via this DMI-trackable bacterial microrobotic system. Finally, we use an anatomically realistic numerical breast phantom as a platform to demonstrate the feasibility of this tumor diagnostic method.

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Gomez-Tames, Jose, Yuto Fukuhara, Siyu He, Kazuyuki Saito, Koichi Ito, and Wenwei Yu. "A human-phantom coupling experiment and a dispersive simulation model for investigating the variation of dielectric properties of biological tissues." Computers in Biology and Medicine 61 (June 2015): 144–49. http://dx.doi.org/10.1016/j.compbiomed.2015.03.029.

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Irastorza, Ramiro M., Sergio Valente, Fernando Vericat, and Eugenia Blangino. "Dielectric Properties in Fresh Trabecular Bone Tissue from 1MHz to 1000MHz: A Fast and Non Destructive Quality Evaluation Technique." Materials Science Forum 638-642 (January 2010): 730–35. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.730.

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The increasing research on development of novel bio-materials has resulted in several studies on non-destructive evaluation methods for characterizing these materials and the biological materials receiving them. A broad range of techniques are available. As an alternative tool, electrical impedance spectroscopy, has become a widely used, non destructive and low cost technique in material quality evaluation. Particularly in bones, it has also been demonstrated that mechanical characteristics are strongly correlated to dielectric properties. In this work, non destructive estimation (the same samples can be tested using other techniques) of the dielectric properties of fresh trabecular bones (layered lossy structure) using coaxial probes is analyzed from 1MHz to 10MHz (in frequency domain) and from 80MHz to 1GHz (in both, frequency and time domain). Frequency domain system identification is used to build the estimation in the low frequency range and an orthonormal based identification approach, for the high frequency data. Comments on conductive samples, non Debye dielectrics and polarization effects are added. The methodology was applied to a particular human sample population of aged adult femur heads and results are presented here. A comparison with destructive test, in which the samples were machined into cylinders of 7mm diameter, is also performed.

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Di Meo, Simona, Giulia Matrone, and Marco Pasian. "Experimental Validation on Tissue-Mimicking Phantoms of Millimeter-Wave Imaging for Breast Cancer Detection." Applied Sciences 11, no. 1 (January 4, 2021): 432. http://dx.doi.org/10.3390/app11010432.

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Breast cancer is one of the leading causes of cancer death among women; to decrease the death rate for this disease, early detection plays a key role. Recently, microwave imaging systems have been proposed as an alternative to the current techniques, but they suffer from poor resolution due to the low frequencies involved. In this paper, for the first time, an innovative millimeter-wave imaging system for early-stage breast cancer detection is proposed and experimentally verified on different breast phantoms. This has the potential to achieve superior resolution for breasts with a high volumetric percentage of adipose tissue, and the merit to overcome the common misconception that millimeter-waves cannot achieve useful penetration depths for biological applications. Three phantoms were prepared according to the dielectric properties of human breast ex vivo tissues in the frequency range [0.5–50] GHz. Two cylindrical inclusions made by water and gelatin or agar, mimicking dielectric properties of neoplastic tissues, were embedded in the phantom at different depths up to 3 cm. Two double ridge waveguides, with mono-modal frequency band equal to [18–40] GHz, were used to synthetize a linear array of 24 elements in 28 positions, acquiring signals with a Vector Network Analyzer. The images were reconstructed by applying the Delay and Sum algorithm to calibrated data. The feasibility of a new imaging system with a central working frequency of about 30 GHz is experimentally demonstrated for the first time, and a target detection capability up to 3 cm within the phantom is shown. The presented results pave the way for a possible use of millimeter-waves to image non-superficial neoplasms in the breast.

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Farsaci, Francesco, Annamaria Russo, Silvana Ficarra, and Ester Tellone. "Dielectric Properties of Human Normal and Malignant Liver Tissue: A Non-Equilibrium Thermodynamics Approach." OALib 02, no. 03 (2015): 1–12. http://dx.doi.org/10.4236/oalib.1101395.

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Nopp, P., N. D. Harris, T. X. Zhao, and B. H. Brown. "Model for the dielectric properties of human lung tissue against frequency and air content." Medical & Biological Engineering & Computing 35, no. 6 (November 1997): 695–702. http://dx.doi.org/10.1007/bf02510980.

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Silaghi, A. M., U. L. Rohde, A. K. Poddar, H. Silaghi, T. I. Ilias, and O. C. Fratila. "Important Aspects of Human Blood Exposure in the Radio and Microwave Field." Scientific Bulletin of Electrical Engineering Faculty 19, no. 1 (April 1, 2019): 23–27. http://dx.doi.org/10.1515/sbeef-2019-0005.

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AbstractTo expose humans to microwave emissions damages biological welfare. For measuring the dielectric properties of biological tissues, it was studied whether current safety standard recommendations are inappropriate as far as human blood function is concerned. Thirty age and gender matched blood samples will serve as control. For increased accuracy detection of any possible alteration and to help orientate towards the details that are to be studied ultra-structurally, a special stain was used. An electronic microscope analysis will be performed on all the blood samples after specific preparation to see whether such microwave exposure might affect the ultra-structure of the blood cells. After modeling and sectioning the blocks were contrasted using acetate-uranyl and lead-citrate and study them with an electronic microscope. The obtained images are processed using Viewer Imaging Analysis software for further analysis. In the end, scanning microscopy must be used in order to detect any surface dimorphisms that might appear due to the microwave exposure.

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Izdihar, Kamal, Hairil Rashmizal Abdul Razak, Nurzulaikha Supion, Muhammad Khalis Abdul Karim, Nurul Huda Osman, and Mazlan Norkhairunnisa. "Structural, Mechanical, and Dielectric Properties of Polydimethylsiloxane and Silicone Elastomer for the Fabrication of Clinical-Grade Kidney Phantom." Applied Sciences 11, no. 3 (January 27, 2021): 1172. http://dx.doi.org/10.3390/app11031172.

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This study aimed to introduce an alternative, inexpensive, and straightforward polymer with specific mechanical and dielectric properties suitable for the fabrication of a clinical-grade kidney phantom. Two polymer-based phantom materials, polydimethylsiloxane (PDMS) and silicone elastomer (SE), were investigated for their capability to meet the requirements. The concentration ratios of base to curing agent (B/C) were 9.5/1.5, 19/3, 10/1, 20/2, 10.5/0.5, and 21/1 for PDMS and 4.5/5.5, 10/12, 5/5, 11/11, 5.5/4.5, and 12/10 for SE. All samples were mixed, degassed, and poured into Petri dishes and small beakers. The polymer was cured under room temperature for 2 h and then demolded from the hard mold. The air bubbles produced were removed using a vacuum desiccator for 30 min. All samples underwent mechanical testing (tensile strength and elastic modulus), and their dielectric properties were measured using a dielectric probe kit equipped with 85071E materials measurement software. The radiation attenuation properties were also measured using PhyX-Zetra for PDMS phantoms with the chemical formula C2H6OSi. Small changes in base and cross-linker play an essential role in modifying the elastic modulus and tensile strength. The effective atomic number of PDMS showed a similar pattern with human kidney tissue at the intermediate energy level of 1.50 × 10−1 to 1 MeV. Therefore, PDMS can potentially be used to mimic the human kidney in terms of tensile strength, flexibility, the acceptable real part of the complex dielectric constant ε′r, and conductivity, which allows it to be used as a stable kidney phantom for medical imaging purposes.

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Kissi, Chaïmaâ, Mariella Särestöniemi, Timo Kumpuniemi, Marko Sonkki, Sami Myllymäki, Mohamed Nabil Srifi, and Carlos Pomalaza-Raez. "On-body Cavity-Backed Low-UWB Antenna for Capsule Localization." International Journal of Wireless Information Networks 27, no. 1 (September 30, 2019): 30–44. http://dx.doi.org/10.1007/s10776-019-00460-9.

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Abstract The paper presents a novel antenna operating at the lower UWB band (3.75–4.25 GHz), defined originally in IEEE 802.15.6 standard for Body Area Networks (BAN) applications. The proposed antenna is designed for biomedical application, wireless capsule endoscopy localization. In other words, the concerned application is dedicated to track a capsule, by means of an external device, swallowed by the patient to provide captured images of the Small Intestine (SI), essential part of the GastroIntestinal (GI) tract, and transfer them in real-time to the external device. In this context, antenna with and without cavity-backed structures, are presented and compared with the requirements for a receiving antenna in terms of directivity and bandwidth coverage in question. It was revealed that the cavity approach improved the antenna gain up to 8 dBi, at the 4 GHz center frequency, compared to 6 dBi without the cavity presence. Simulations were carried out using CST Microwave Studio, and the results were validated by measurements in proximity to human body. The antenna safety issue was assessed with CST SAR (Specific Absorption Rate) calculation, in compliance with IEEE/IEC 62704-1 standard. Results showed a maximum SAR of 0.112 W/kg and 0.005 W/kg at 4 mm and 30 mm antenna-skin distance, in the range of the SAR limit guidelines defined by safety standards. The cavity-backed antenna ability to penetrate the human tissues, to reach the small intestine layer was studied by means of CST voxel model and compared to a multi-layer model emulating the dielectric properties of the human tissues at 4 GHz. This analysis was conducted using power flow results and completed by the power field probes at the several tissue interfaces.

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Williams, Paul Allen, and Subrata Saha. "The electrical and dielectric properties of human bone tissue and their relationship with density and bone mineral content." Annals of Biomedical Engineering 24, no. 2 (March 1996): 222–33. http://dx.doi.org/10.1007/bf02667351.

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Jemima Priyadarshini, S., and D. Jude Hemanth. "Investigation of Nanomaterial Dipoles for SAR Reduction in Human Head." Frequenz 73, no. 5-6 (May 27, 2019): 189–201. http://dx.doi.org/10.1515/freq-2018-0220.

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Abstract The Nanomaterial is a pioneer in the field of modern research for its unique properties. Human exposure analysis is inevitable due to the rapid growth in technology. The concern for human welfare indicates a need for reduction of human exposure towards the radiation caused by the devices. The dielectric properties of the nanomaterials can be ideal for exploration in the field of biomedical engineering. Specific absorption rate (SAR) is a vital parameter for exposure analysis. This paper investigates the impact of Nanomaterials on the human exposure analysis. For this purpose, a dipole radiating structure operating at GSM frequency of 900 MHz and 1800 MHz are designed with conventional Copper material and compared with Carbon nanomaterials such as Graphene, Single-walled carbon nanotube (SWCNT) and Multi-walled carbon nanotube (MWCNT) for performance evaluation. Further, the specific absorption rate estimates absorption of radiation in IEEE Sam phantom human head with equivalent tissue properties. The comparison of calculated SAR with the radiating structures that are designed with the equivalent properties of that of Nanomaterials. The evaluation of Nanomaterial Antennas at the center frequency is estimated, and performance is evaluated. The designed Nanomaterials interact with IEEE SAM Phantom and SAR is calculated. The analysis of SAR impact with nanomaterials is investigated in this work.

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Anand, Gautam, Andrew Lowe, and Ahmed Al-Jumaily. "Tissue phantoms to mimic the dielectric properties of human forearm section for multi-frequency bioimpedance analysis at low frequencies." Materials Science and Engineering: C 96 (March 2019): 496–508. http://dx.doi.org/10.1016/j.msec.2018.11.080.

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Schmid, Gernot, Georg Neubauer, and Peter R. Mazal. "Dielectric properties of human brain tissue measured less than 10 h postmortem at frequencies from 800 to 2450 MHz." Bioelectromagnetics 24, no. 6 (August 11, 2003): 423–30. http://dx.doi.org/10.1002/bem.10123.

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Scapaticci, Rosa, Vanni Lopresto, Rosanna Pinto, Marta Cavagnaro, and Lorenzo Crocco. "Monitoring Thermal Ablation via Microwave Tomography: An Ex Vivo Experimental Assessment." Diagnostics 8, no. 4 (December 6, 2018): 81. http://dx.doi.org/10.3390/diagnostics8040081.

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Thermal ablation treatments are gaining a lot of attention in the clinics thanks to their reduced invasiveness and their capability of treating non-surgical patients. The effectiveness of these treatments and their impact in the hospital’s routine would significantly increase if paired with a monitoring technique able to control the evolution of the treated area in real-time. This is particularly relevant in microwave thermal ablation, wherein the capability of treating larger tumors in a shorter time needs proper monitoring. Current diagnostic imaging techniques do not provide effective solutions to this issue for a number of reasons, including economical sustainability and safety. Hence, the development of alternative modalities is of interest. Microwave tomography, which aims at imaging the electromagnetic properties of a target under test, has been recently proposed for this scope, given the significant temperature-dependent changes of the dielectric properties of human tissues induced by thermal ablation. In this paper, the outcomes of the first ex vivo experimental study, performed to assess the expected potentialities of microwave tomography, are presented. The paper describes the validation study dealing with the imaging of the changes occurring in thermal ablation treatments. The experimental test was carried out on two ex vivo bovine liver samples and the reported results show the capability of microwave tomography of imaging the transition between ablated and untreated tissue. Moreover, the discussion section provides some guidelines to follow in order to improve the achievable performances.

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Savazzi, Matteo, Soroush Abedi, Niko Ištuk, Nadine Joachimowicz, Hélène Roussel, Emily Porter, Martin O’Halloran, et al. "Development of an Anthropomorphic Phantom of the Axillary Region for Microwave Imaging Assessment." Sensors 20, no. 17 (September 2, 2020): 4968. http://dx.doi.org/10.3390/s20174968.

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We produced an anatomically and dielectrically realistic phantom of the axillary region to enable the experimental assessment of Axillary Lymph Node (ALN) imaging using microwave imaging technology. We segmented a thoracic Computed Tomography (CT) scan and created a computer-aided designed file containing the anatomical configuration of the axillary region. The phantom comprises five 3D-printed parts representing the main tissues of interest of the axillary region for the purpose of microwave imaging: fat, muscle, bone, ALNs, and lung. The phantom allows the experimental assessment of multiple anatomical configurations, by including ALNs of different size, shape, and number in several locations. Except for the bone mimicking organ, which is made of solid conductive polymer, we 3D-printed cavities to represent the fat, muscle, ALN, and lung and filled them with appropriate tissue-mimicking liquids. Existing studies about complex permittivity of ALNs have reported limitations. To address these, we measured the complex permittivity of both human and animal lymph nodes using the standard open-ended coaxial-probe technique, over the 0.5 GHz–8.5 GHz frequency band, thus extending current knowledge on dielectric properties of ALNs. Lastly, we numerically evaluated the effect of the polymer which constitutes the cavities of the phantom and compared it to the realistic axillary region. The results showed a maximum difference of 7 dB at 4 GHz in the electric field magnitude coupled to the tissues and a maximum of 10 dB difference in the ALN response. Our results showed that the phantom is a good representation of the axillary region and a viable tool for pre-clinical assessment of microwave imaging technology.

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Mahmud, Md, Mohammad Islam, Norbahiah Misran, Ali Almutairi, and Mengu Cho. "Ultra-Wideband (UWB) Antenna Sensor Based Microwave Breast Imaging: A Review." Sensors 18, no. 9 (September 5, 2018): 2951. http://dx.doi.org/10.3390/s18092951.

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Globally, breast cancer is reported as a primary cause of death in women. More than 1.8 million new breast cancer cases are diagnosed every year. Because of the current limitations on clinical imaging, researchers are motivated to investigate complementary tools and alternatives to available techniques for detecting breast cancer in earlier stages. This article presents a review of concepts and electromagnetic techniques for microwave breast imaging. More specifically, this work reviews ultra-wideband (UWB) antenna sensors and their current applications in medical imaging, leading to breast imaging. We review the use of UWB sensor based microwave energy in various imaging applications for breast tumor related diseases, tumor detection, and breast tumor detection. In microwave imaging, the back-scattered signals radiating by sensors from a human body are analyzed for changes in the electrical properties of tissues. Tumorous cells exhibit higher dielectric constants because of their high water content. The goal of this article is to provide microwave researchers with in-depth information on electromagnetic techniques for microwave imaging sensors and describe recent developments in these techniques.

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Gamal, W., H. Wu, I. Underwood, J. Jia, S. Smith, and P. O. Bagnaninchi. "Impedance-based cellular assays for regenerative medicine." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1750 (May 21, 2018): 20170226. http://dx.doi.org/10.1098/rstb.2017.0226.

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Therapies based on regenerative techniques have the potential to radically improve healthcare in the coming years. As a result, there is an emerging need for non-destructive and label-free technologies to assess the quality of engineered tissues and cell-based products prior to their use in the clinic. In parallel, the emerging regenerative medicine industry that aims to produce stem cells and their progeny on a large scale will benefit from moving away from existing destructive biochemical assays towards data-driven automation and control at the industrial scale. Impedance-based cellular assays (IBCA) have emerged as an alternative approach to study stem-cell properties and cumulative studies, reviewed here, have shown their potential to monitor stem-cell renewal, differentiation and maturation. They offer a novel method to non-destructively assess and quality-control stem-cell cultures. In addition, when combined with in vitro disease models they provide complementary insights as label-free phenotypic assays. IBCA provide quantitative and very sensitive results that can easily be automated and up-scaled in multi-well format. When facing the emerging challenge of real-time monitoring of three-dimensional cell culture dielectric spectroscopy and electrical impedance tomography represent viable alternatives to two-dimensional impedance sensing. This article is part of the theme issue ‘Designer human tissue: coming to a lab near you’.

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Wang, Hang, Lei Wang, Lin Yang, Xuetao Shi, Zhihong Wen, and Xiuzhen Dong. "Exploring the relationship between the dielectric properties and viability of human normal hepatic tissues from 10 Hz to 100 MHz based on grey relational analysis and BP neural network." Computers in Biology and Medicine 134 (July 2021): 104494. http://dx.doi.org/10.1016/j.compbiomed.2021.104494.

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Zidane, Mohamed Amine, Hichem Amar, and Amar Rouane. "Study of Two Constraints Impacting Measurements of Human Glycemia Using a Microwave Sensor." Biosensors 11, no. 3 (March 15, 2021): 83. http://dx.doi.org/10.3390/bios11030083.

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The measurement of glycemia is impacted by several constraints; those constraints have to be identified and quantified when designing an electromagnetic noninvasive sensor. The second phase concerns the level of the influence of these constraints. In this work, we investigated the impact of vein radius located in the forearm on a resonant microwave sensor to measure glycemia. We performed a numerical simulation using COMSOL Multiphysics of a proposed tissue model that was in contact with a microwave resonator. Some other factors affect the measurement, such as temperature, perfusion, sensor positioning and motion, tissue heterogeneity, and other biological activity. The sensor must be robust to the above-mentioned constraints. Because vein size changes from one person to another, the dielectric properties seen by the sensor will be different. This has been demonstrated by the change created in the resonance frequency of the simulated sensor for different vein sizes. The second constraint that was assessed is the dosimetry. The specific absorption rate (SAR) of any electromagnetic device should be evaluated and compared with SAR limits in the safety standards to ensure the safety of the user. Simulation results are in good agreement with SAR limits in the safety standards.

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Kiourti, Asimina, and Konstantina S. Nikita. "Design of Implantable Antennas for Medical Telemetry." International Journal of Monitoring and Surveillance Technologies Research 1, no. 1 (January 2013): 16–33. http://dx.doi.org/10.4018/ijmstr.2013010102.

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Implantable Medical Devices (IMDs) with wireless telemetry functionalities in the radio-frequency (RF) range are recently attracting significant scientific interest for medical prevention, diagnosis, and therapy. One of the most crucial challenges for IMDs is the design of the integrated implantable antenna which enables bidirectional wireless communication between the IMD and exterior monitoring/control equipment. In this paper, a parametric model of a miniature implantable antenna is initially proposed, which can be adjusted to suit any antenna design and implantation scenario requirements in hand. Dependence of the resonance, radiation, and safety performance of implantable antennas upon (a) operation frequency, (b) tissue anatomy and dielectric properties, and (c) implantation site is further studied. Simulations are carried out: (a) at 402, 433, 868 and 915 MHz considering a 13-tissue anatomical head model, (b) at 402 MHz considering five head models (3- and 5-layer spherical, 6-, 10- and 13-tissue anatomical) and seven dielectric parameter scenarios (variations ±20% in the reference permittivity and conductivity values), and (c) at 402 MHz considering 3-layer canonical models of the human head, arm, and trunk. The study provides valuable insight into the design of implantable antennas. Finite Element and Finite Difference Time Domain numerical solvers are used.

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Kumar, S. Ashok, and T. Shanmuganantham. "Implantable CPW Fed Circular Slot Antennas at 2.45 GHz ISM Band for Biomedical Applications." Journal of Circuits, Systems and Computers 24, no. 01 (November 10, 2014): 1550014. http://dx.doi.org/10.1142/s0218126615500140.

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A novel coplanar waveguide (CPW) fed circular slot antennas are proposed for industrial, scientific and medical (ISM) band (2.4–2.48 GHz) applications. To make the designed antenna suitable for implantation, it is embedded in biocompatible Al2O3 ceramic substrate. The antenna was simulated by immersing it in a phantom liquid, imitating the electrical properties of the human muscle tissue. A study of the sensitivity of the antenna performance as a function of the dielectric parameters of the environment in which it is immersed was performed. Simulations in various dimensions state demonstrate that the antenna covers the complete ISM band. The demonstration among the design EM characteristics of the antenna is presented by current distributions.

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Schmid, Gernot, Richard Überbacher, Theodoros Samaras, Manfred Tschabitscher, and Peter R. Mazal. "The dielectric properties of human pineal gland tissue and RF absorption due to wireless communication devices in the frequency range 400–1850 MHz." Physics in Medicine and Biology 52, no. 17 (August 21, 2007): 5457–68. http://dx.doi.org/10.1088/0031-9155/52/17/024.

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Li, Shu, Zengwen Su, Hao Wang, Quan Wang, and Haiping Ren. "Research on an Anthropomorphic Phantom for Evaluation of the Medical Device Electromagnetic Field Exposure SAR." Applied Sciences 8, no. 10 (October 15, 2018): 1929. http://dx.doi.org/10.3390/app8101929.

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A medical device will emit electromagnetic radiation to its surrounding environment either actively or passively. However, clinicians are unaware as to whether the ambient electromagnetic radiation will exceed the human body’s endurance capacity. In this paper, the mathematical model of electromagnetic parameters devoted to Specific Absorption Rate (SAR) testing of medical devices was established using a Debye Model. Body liquids featuring dielectric properties including the conductivity and permittivity of tissues at various body parts were simulated on the basis of results derived from the model. A simplified anthropomorphic phantom for the SAR test was founded on the basis of geometric parameters by following the principles of resemblance and consistent conductivity. A full-band electromagnetic mathematical model of brain, muscle, heart, lungs, stomach, and kidneys was set up. Electromagnetic radiation levels of a wearable Electrocardiograph monitoring device were measured and found that the maximum electric field intensity was up to 30 V/m, and the electromagnetic radiation SAR value was 0.96 W/kg, which were equivalent to the electromagnetic radiation exposure of the occupational group. The results established that electromagnetic radiation of certain medical devices exceeded the allowed values specified by the World Health Organization (WHO). Therefore, further studies within the field of medicine are required to decide whether additional evaluation measures should be required.

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Tatara, T., and K. Tsuzaki. "Derivation of extracellular fluid volume fraction and equivalent dielectric constant of the cell membrane from dielectric properties of the human body. Part 1: Incorporation of fat tissue into cell suspension model in the arm." Medical & Biological Engineering & Computing 38, no. 4 (July 2000): 377–83. http://dx.doi.org/10.1007/bf02345005.

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Tatara, T., and K. Tsuzaki. "Derivation of extracellular fluid volume fraction and equivalent dielectric constant of the cell membrane from dielectric properties of the human body. Part 2: A preliminary study for tracking the progression of surgical tissue injury." Medical & Biological Engineering & Computing 38, no. 4 (July 2000): 384–89. http://dx.doi.org/10.1007/bf02345006.

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Pethig, R. "Dielectric properties of body tissues." Clinical Physics and Physiological Measurement 8, no. 4A (November 1987): 5–12. http://dx.doi.org/10.1088/0143-0815/8/4a/002.

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Xia, Yun, Qi Zhang, Xue E. Wu, Tim V. Kirk, and Xiao Dong Chen. "Practical and Durable Flexible Strain Sensors Based on Conductive Carbon Black and Silicone Blends for Large Scale Motion Monitoring Applications." Sensors 19, no. 20 (October 19, 2019): 4553. http://dx.doi.org/10.3390/s19204553.

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Presented is a flexible capacitive strain sensor, based on the low cost materials silicone (PDMS) and carbon black (CB), that was fabricated by casting and curing of successive silicone layers—a central PDMS dielectric layer bounded by PDMS/CB blend electrodes and packaged by exterior PDMS films. It was effectively characterized for large flexion-angle motion wearable applications, with strain sensing properties assessed over large strains (50%) and variations in temperature and humidity. Additionally, suitability for monitoring large tissue deformation was established by integration with an in vitro digestive model. The capacitive gauge factor was approximately constant at 0.86 over these conditions for the linear strain range (3 to 47%). Durability was established from consistent relative capacitance changes over 10,000 strain cycles, with varying strain frequency and elongation up to 50%. Wearability and high flexion angle human motion detection were demonstrated by integration with an elbow band, with clear detection of motion ranges up 90°. The device’s simple structure and fabrication method, low-cost materials and robust performance, offer promise for expanding the availability of wearable sensor systems.

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Papezova, Maria, and Dagmar Faktorova. "MICROWAVE PROPAGATION IN TOOTH AND DENTAL DEFECT." CBU International Conference Proceedings 4 (September 16, 2016): 658–61. http://dx.doi.org/10.12955/cbup.v4.828.

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INTRODUCTION:The most common method of conventional dental diagnosisinvolves X-rays, such as Radio Tomography (RT) or Computer Tomography (CT). Such methods are used for diagnosing pores in dental material that can lead to premature failure of dental material. Diagnosis by X-ray provides an objective analysis. However, repeated radiation from X-rays can cause biological damage to human tissues. From this point of view, there is a significant need to progress to quantitative non-invasive and non-destructive testing (NDT) methods to measure dental material and improve treatment options. This article focuses on applying microwave technology to characterize teeth and teeth replacements. Knowledge of microwave propagation in biomaterial with no defects, using a defined microwave frequency range, and subsequently comparing the result with defective material could provide a means of dental diagnosis without the risk of radiation for the patient, i.e. without X-ray. OBJECTIVES: The primary objective of this study was to examine microwave technology in the field of dental medical diagnosis as a new NDT method. METHODS: The basic concept of applying microwave technology to characterize teeth in dental diagnosis was examined using a basic algorithm designed in the MATLAB programming language. Tests used dielectric properties of tooth and tooth decay and propagated electromagnetic (EM) waves to show different characteristics of chosen materials.RESULTS: The analyses of frequency dependent reflection and transmission coefficients of the chosen material, specificallyteeth, atfrequency range 0 GHz to 30 GHz, computed differences between healthy and defective dental material.CONCLUSION: Thus, this could be used in providing a dental diagnosis without exposing patients to radiation, i.e. without X-ray. The next stage will involve creating a complete model of a jaw with teeth, and designing a sensor for crack detection for comparisons using this basic algorithm.

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Smith, S. R., and K. R. Foster. "Dielectric properties of low-water-content tissues." Physics in Medicine and Biology 30, no. 9 (September 1, 1985): 965–73. http://dx.doi.org/10.1088/0031-9155/30/9/008.

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Journal articles on the topic 'Dielectric properties of human tissues'

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