Journal articles: 'Dielectric properties of biological tissues'

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La Gioia, Alessandra, Martin O’Halloran, and Emily Porter. "Challenges of Post-measurement Histology for the Dielectric Characterisation of Heterogeneous Biological Tissues." Sensors 20, no. 11 (2020): 3290. http://dx.doi.org/10.3390/s20113290.

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The dielectric properties of biological tissues are typically measured using the open-ended coaxial probe technique, which is based on the assumption that the tissue sample is homogeneous. Therefore, for heterogeneous tissue samples, additional post-measurement sample processing is conducted. Specifically, post-measurement histological analysis may be performed in order to associate the measured dielectric properties with the tissue types present in a heterogeneous sample. Accurate post-measurement histological analysis enables identification of the constituent tissue types that contributed to the measured dielectric properties, and their relative distributions. There is no standard protocol for conducting post-measurement histological analysis, which leads to high numbers of excluded tissue samples and inconsistencies in the resulting reported data for heterogeneous tissues. To this extent, this study examines the post-measurement histological process and the challenges in associating the acquired dielectric properties with the different tissue types present in heterogeneous samples. The results demonstrate that the histological process inevitably alters the morphology of samples, thus introducing errors in the interpretation of the dielectric properties acquired from heterogeneous biological samples. Notably, sample size was seen to shrink by up to 90% through the histological process, meaning that sensing volume determined from fresh tissues is not directly applicable to histology images.

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Gerazov, Branislav, Daphne Anne Caligari Conti, Laura Farina, et al. "Application of Machine Learning to Predict Dielectric Properties of In Vivo Biological Tissue." Sensors 21, no. 20 (2021): 6935. http://dx.doi.org/10.3390/s21206935.

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In this paper we revisited a database with measurements of the dielectric properties of rat muscles. Measurements were performed both in vivo and ex vivo; the latter were performed in tissues with varying levels of hydration. Dielectric property measurements were performed with an open-ended coaxial probe between the frequencies of 500 MHz and 50 GHz at a room temperature of 25 °C. In vivo dielectric properties are more valuable for creating realistic electromagnetic models of biological tissue, but these are more difficult to measure and scarcer in the literature. In this paper, we used machine learning models to predict the in vivo dielectric properties of rat muscle from ex vivo dielectric property measurements for varying levels of hydration. We observed promising results that suggest that our model can make a fair estimation of in vivo properties from ex vivo properties.

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Gabriel, S., R. W. Lau, and C. Gabriel. "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues." Physics in Medicine and Biology 41, no. 11 (1996): 2271–93. http://dx.doi.org/10.1088/0031-9155/41/11/003.

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Bocharin, Ivan, Andrew Martusevich, Vladimir Nazarov, Elena S. Golygina, Inessa A. Minenko, and Mikhail Yu Artamonov. "Dielectric properties of the tissues with different histological structure: Ex vivo study." Journal of Experimental Biology and Agricultural Sciences 10, no. 2 (2022): 451–55. http://dx.doi.org/10.18006/2022.10(2).451.455.

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This study aimed to estimate the dielectric properties of tissues with different histological structures. For this, specimens of fibrous (n=9), muscular (n=7), and fatty (n=11) human tissues were studied. The estimation of dielectric permittivity and conductivity of these specimens was tested with a program and apparatus device for near-field resonance microwave sensing, including 5 applicators with different depths of study. Results of the study demonstrated that this technology can visualize the shape, localization, and linear decisions of biological objects. The currently used method allows distinguishing the tissue histological type. It was stated that fibrous tissue has a maximal level of median and highest dielectric permittivity, and the minimal value of this parameter was fixed for fatty specimens (in 4.26 and 4.53 times lower than in fibrous one, respectively). Muscular tissue has an intermediate value of dielectric permittivity, approaching a level close to fibrous tissue.

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Cherukuri, Akhila Sai Sree, Vaishnavi Kalpesh Modi, Bhavana Baraskar, et al. "Microwave-Based Dielectric Properties as an Electrophysiological Biomarker: Future Perspectives." Electronics 12, no. 15 (2023): 3276. http://dx.doi.org/10.3390/electronics12153276.

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Electrophysiology is the study of the electrical properties of biological tissues, which involves the movement of ions across cell membranes. The analysis of the movement of electrical charges through the body has a wide range of biomedical applications, such as diagnosing and planning treatment in cardiovascular, nervous systems, muscular, and gastrointestinal disorders. The dielectric properties of biological tissues change according to the water content in the tissue and are measured as permittivity and conductivity relative to the frequency of the electrical field. This principle has been applied in diagnostics and therapeutics using microwave energysuch as imaging and ablation, etc. This review article summarizes the potential use of measuring dielectric properties using microwave imaging and how it can augment electrophysiological studies in medicine.

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Gabriel, C., S. Gabriel, and E. Corthout. "The dielectric properties of biological tissues: I. Literature survey." Physics in Medicine and Biology 41, no. 11 (1996): 2231–49. http://dx.doi.org/10.1088/0031-9155/41/11/001.

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Aydinalp, Cemanur, Sulayman Joof, and Tuba Yilmaz. "Towards Accurate Microwave Characterization of Tissues: Sensing Depth Analysis of Open-Ended Coaxial Probes with Ex Vivo Rat Breast and Skin Tissues." Diagnostics 11, no. 2 (2021): 338. http://dx.doi.org/10.3390/diagnostics11020338.

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Dielectric properties of biological materials are commonly characterized with open-ended coaxial probes due to the broadband and non-destructive measurement capabilities. Recently, potential diagnostics applications of the technique have been investigated. Although the technique can successfully classify the tissues with different dielectric properties, the classification accuracy can be improved for tissues with similar dielectric properties. Increase in classification accuracy can be achieved by addressing the error sources. One well-known error source contributing to low measurement accuracy is tissue heterogeneity. To mitigate this error source, there is a need define the probe sensing depth. Such knowledge can enable application-specific probe selection or design. The sensing depth can also be used as an input to the classification algorithms which can potentially improve the tissue classification accuracy. Towards this goal, this work investigates the sensing depth of a commercially available 2.2 mm aperture diameter probe with double-layered configurations using ex vivo rat breast and skin tissues. It was concluded that the dielectric property contrast between the heterogeneous tissue components has an effect on the sensing depth. Also, a membrane layer (between 0.4–0.8 mm thickness) on the rat wet skin tissue and breast tissue will potentially affect the dielectric property measurement results by 52% to 84%.

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Sabouni, Abas, Camerin Hahn, Sima Noghanian, Edward Sauter, and Tim Weiland. "Study of the Effects of Changing Physiological Conditions on Dielectric Properties of Breast Tissues." ISRN Biomedical Imaging 2013 (July 31, 2013): 1–5. http://dx.doi.org/10.1155/2013/894153.

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This paper addresses the changes in the physical characteristics (temperature and water/blood content) of breast tissue under different physiological conditions. We examined ex vivo specimens of breast tissue excised at the time of surgery to study the effects of physiological conditions on dielectric properties. We observed that the dielectric properties strongly depend on tissue physiological state. When the biological tissues undergo physiological changes, such as those due to disease or those induced by external changes such as variations in the environmental temperature, the microscopic processes deviate from their normal state and impact the overall dielectric properties. This suggests that microwave imaging might be used to monitor the physiological conditions of the body.

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Kang, Jin-Seob, Young Seung Lee, and Youngcheol Park. "Free-Space Dielectric Property Measurement of Biological Tissues at W-Band Frequencies." Journal of Electromagnetic Engineering and Science 25, no. 2 (2025): 109–17. https://doi.org/10.26866/jees.2025.2.r.283.

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This paper presents a free-space measurement method for the dielectric properties of small biological tissues (in this study, micropig skins that are 60 mm × 60 mm in size and 1.4 mm in thickness are used) that do not meet the size requirement of conventional free-space material measurement at W-band (75–110 GHz) frequencies. The first step involved enhancing the material under test (MUT) holder of an existing free-space material measurement system to ensure the reliable measurement of small biological tissues. This enhancement was confirmed by comparing the measured dielectric properties of an air gap with its theoretical properties. The measured dielectric properties of the micropig skins were then validated through a comprehensive comparison using data based on the double Cole-Cole parametric model, which is a widely referenced model in many numerical dosimetry studies. The good agreement between the two results demonstrates the effectiveness of the proposed free-space material measurement method, as well as the reliability of the measured dielectric property of micropig skins.

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Liporace, Flavia, Gianluca Ciarleglio, Maria Gabriella Santonicola, and Marta Cavagnaro. "Reconstruction of the Permittivity of Ex Vivo Animal Tissues in the Frequency Range 1–20 GHz Using a Water-Based Dielectric Model." Sensors 24, no. 16 (2024): 5338. http://dx.doi.org/10.3390/s24165338.

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Several medical techniques are based on the application of electromagnetic fields (EMFs) on the human body with therapeutic and/or diagnostic aims. The response of human tissues to the applied EMF is mediated by the tissues’ dielectric properties, which must therefore be characterized at the frequencies of the considered technique. Due to the heterogeneity and complexity of biological tissues, it is necessary to know their properties in vivo for the specific condition of interest. Traditional techniques for the dielectric characterization of biological tissues are invasive and, as such, not adoptable for this aim. Accordingly, alternative sensors and/or sensing methods are needed. Recently, a new wideband spectroscopy technique was proposed, based on quantities derived from the Magnetic Resonance (MRI) signal. Among these quantities, the water content was proposed to evaluate the dielectric properties at frequencies around a few GHz. This work verifies the possibility of deriving tissues’ dielectric properties in the frequency range of 1–20 GHz based on knowledge of the water content. The water content was retrieved through a dehydration procedure for five different ex vivo tissues. The achieved results were compared with references from the literature.

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Maurya, Dr M. K. "Microwave Frequency Analysis of Dielectric Properties in Biological Tissues: Insights into Dielectric Constant, Conductivity, and Resistivity at 9.4 GHz." International Journal for Research in Applied Science and Engineering Technology 12, no. 9 (2024): 916–23. http://dx.doi.org/10.22214/ijraset.2024.64288.

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This study investigates the dielectric properties of various biological tissues at microwave frequencies, specifically focusing on their dielectric constant, conductivity, resistivity, and loss tangent. Using methods such as Von Hippel’s and Yadav Gandhi’s techniques, the dielectric characteristics of heart, liver, brain, and muscle of chicken tissues were analysed at 9.4 GHz. It is found that tissues with higher water content exhibit greater dielectric constants and conductivities, while those with higher solid content, like liver, display higher resistivity. It has also been observed that tissues with lower dielectric constants and conductivities are those with greater absorption indices, which are typically associated with increased energy dissipation as heat. An increasing amount of energy dissipation may result from tissues with higher absorption rates being less effective at transferring microwave energy, as suggested by this inverse connection, which also emphasizes the complexity of electromagnetic wave interaction within tissues. This work provides critical insights into the interaction of electromagnetic waves with biological tissues, which is essential for applications in medical diagnostics, therapeutic technologies, and electromagnetic exposure safety standards.

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Relva, Mariana, and Susana Devesa. "Dielectric Stability of Triton X-100-Based Tissue-Mimicking Materials for Microwave Imaging." Spectroscopy Journal 1, no. 2 (2023): 72–85. http://dx.doi.org/10.3390/spectroscj1020007.

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Microwave imaging is an emerging technology, and has been proposed for various applications, namely as an alternative diagnostic technology. Microwave imaging explores the dielectric contrast of target tissues, enabling diagnosis based on the differences in dielectric properties between healthy and diseased tissues, with low cost, portability and non-ionizing radiation as its main advantages, constituting an alternative to various imaging technologies for diagnosing and monitoring. Before clinical trials of microwave imaging devices for the study of dielectric properties, phantoms are used, mimicking the materials of tissues and simulating the electric properties of human tissues, for device validation. The purpose of this work was to prepare and perform dielectric characterization of mimicking materials for the development of an anthropomorphic phantom of the human ankle with realistic dielectric and anatomic properties. The biological tissues targeted in this investigation were the skin, muscle, cortical bone, trabecular bone and fat, with the mimicking materials prepared using Triton X-100, sodium chloride and distilled water. The dielectric characterization was performed using a coaxial probe, operating at frequencies between 0.5 and 4.0 GHz. Since the stability of the dielectric properties of mimicking materials is one of their main properties, the dielectric characterization was repeated after 15 and 35 days.

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Samaddar, Poulami, Anup Kumar Mishra, Sunil Gaddam, et al. "Machine Learning-Based Classification of Abnormal Liver Tissues Using Relative Permittivity." Sensors 22, no. 24 (2022): 9919. http://dx.doi.org/10.3390/s22249919.

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The search for non-invasive, fast, and low-cost diagnostic tools has gained significant traction among many researchers worldwide. Dielectric properties calculated from microwave signals offer unique insights into biological tissue. Material properties, such as relative permittivity (εr) and conductivity (σ), can vary significantly between healthy and unhealthy tissue types at a given frequency. Understanding this difference in properties is key for identifying the disease state. The frequency-dependent nature of the dielectric measurements results in large datasets, which can be postprocessed using artificial intelligence (AI) methods. In this work, the dielectric properties of liver tissues in three mouse models of liver disease are characterized using dielectric spectroscopy. The measurements are grouped into four categories based on the diets or disease state of the mice, i.e., healthy mice, mice with non-alcoholic steatohepatitis (NASH) induced by choline-deficient high-fat diet, mice with NASH induced by western diet, and mice with liver fibrosis. Multi-class classification machine learning (ML) models are then explored to differentiate the liver tissue groups based on dielectric measurements. The results show that the support vector machine (SVM) model was able to differentiate the tissue groups with an accuracy up to 90%. This technology pipeline, thus, shows great potential for developing the next generation non-invasive diagnostic tools.

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Kamlach, Р. V., D. S. Hroda, A. V. Churakov, et al. "Model of electromagnetic field effect on biological tissues." Doklady BGUIR 18, no. 8 (2020): 46–52. http://dx.doi.org/10.35596/1729-7648-2020-18-8-46-52.

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The design of modern devices for extracorporeal magnetotherapy should be preceded by physical and mathematical modeling of all stages of the technology of the effect of magnetic fields on various types of body tissues, taking into account their dielectric properties. This is necessary to create an electromagnetic field with the necessary biotropic parameters. In this work, a mathematical model of the effect of electromagnetic field on biological tissues, such as muscles, skin and adipose tissue, is constructed. The mathematical model takes into account various parameters of biological tissue, such as electrical conductivity and relative dielectric constant. Based on the model, the parameters of the response in biological tissues (the amplitude of the response in the tissue and the maximum value of the current in the tissue) were calculated in the innovative Sim4Life 5.2 platform. To test the mathematical model, a laboratory model was used to measure the electrical characteristics of biological tissue. During the research, experiments were carried out with three biological samples: adipose tissue, muscle tissue and skin. The dependences of the response amplitude in biological samples on the output signal power are plotted. The results obtained characterize the use of the proposed operation algorithm in a complex based on the Sim4Life 5.2 platform and simulation of electromagnetic field with a biological object that is optimal for the creation and examination of technologies and devices for magnetotherapy and inductors of extracorporeal effects of magnetic field. This work will make it possible to familiarize a wider range of different experts with the capabilities of the platform not only for modeling new medical devices, but also for the examination of available and those already applied in healthcare.

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Canicattì, Eliana, Daniel Álvarez Sánchez-Bayuela, Cristina Romero Castellano, et al. "Dielectric Characterization of Breast Biopsied Tissues as Pre-Pathological Aid in Early Cancer Detection: A Blinded Feasibility Study." Diagnostics 13, no. 18 (2023): 3015. http://dx.doi.org/10.3390/diagnostics13183015.

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Dielectric characterization has significant potential in several medical applications, providing valuable insights into the electromagnetic properties of biological tissues for disease diagnosis, treatment planning, and monitoring of therapeutic interventions. This work presents the use of a custom-designed electromagnetic characterization system, based on an open-ended coaxial probe, for discriminating between benign and malignant breast tissues in a clinical setting. The probe’s development involved a well-balanced compromise between physical feasibility and its combined use with a reconstruction algorithm known as the virtual transmission line model (VTLM). Immediately following the biopsy procedure, the dielectric properties of the breast tissues were reconstructed, enabling tissue discrimination based on a rule-of-thumb using the obtained dielectric parameters. A comparative analysis was then performed by analyzing the outcomes of the dielectric investigation with respect to conventional histological results. The experimental procedure took place at Complejo Hospitalario Universitario de Toledo—Hospital Virgen de la Salud, Spain, where excised breast tissues were collected and subsequently analyzed using the dielectric characterization system. A comprehensive statistical evaluation of the probe’s performance was carried out, obtaining a sensitivity, specificity, and accuracy of 81.6%, 61.5%, and 73.4%, respectively, compared to conventional histological assessment, considered as the gold standard in this investigation.

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Szychta, Leszek, Piotr Jankowski-Mihułowicz, Elżbieta Szychta, et al. "The Dielectric Properties of Worker Bee Homogenate in a High Frequency Electric Field." Energies 15, no. 24 (2022): 9342. http://dx.doi.org/10.3390/en15249342.

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Biological tissues, including insect tissues, are among lossy dielectric materials. The permittivity properties of these materials are described by loss factor ε″ and loss tangent tgδ. The dielectric properties of the worker honeybee body homogenate are tested in the range of high frequencies from 1 MHz to 6 GHz. The homogenate is produced by mixing whole worker honeybees and tested with an epsilometer from Compass Technology and a Copper Mountain Technologies vector circuit analyser VNA. Due to their consistency, the homogenate samples are placed inside polyurethane sachets. The measured permittivity relates to two components of a sample: homogenate and polyurethane. For five samples, two extremes were specified for the permittivity, loss factor ε″, and the loss tangent tgδ, for the frequency range 20 ÷ 80 MHz and 3 GHz. Four techniques of testing permittivity in biological tissues were used to determine the dielectric properties of the homogenate. A calculation model was developed featuring a minimum measurement error of the loss factor ε″ and the loss tangent tgδ. The power absorbed per unit volume is described for the whole frequency range.

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Pollacco, Daphne Anne, Laura Farina, Pierre Schembri Wismayer, Lourdes Farrugia, and Charles V. Sammut. "Characterization of the dielectric properties of biological tissues and their correlation to tissue hydration." IEEE Transactions on Dielectrics and Electrical Insulation 25, no. 6 (2018): 2191–97. http://dx.doi.org/10.1109/tdei.2018.007346.

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W. Kuang and S. O. Nelson. "LOW-FREQUENCY DIELECTRIC PROPERTIES OF BIOLOGICAL TISSUES: A REVIEWWITH SOME NEW INSIGHTS." Transactions of the ASAE 41, no. 1 (1998): 173–84. http://dx.doi.org/10.13031/2013.17142.

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Porter, Emily, Alessandra La Gioia, Adam Santorelli, and Martin O'Halloran. "Modeling of the dielectric properties of biological tissues within the histology region." IEEE Transactions on Dielectrics and Electrical Insulation 24, no. 5 (2017): 3290–301. http://dx.doi.org/10.1109/tdei.2017.006690.

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Li, Gun. "Multi-Phase Dielectric Model of Blood and its Application." Applied Mechanics and Materials 518 (February 2014): 248–51. http://dx.doi.org/10.4028/www.scientific.net/amm.518.248.

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The dielectric property of biological tissue is one of the important electrical properties, which vary with the internal structure, including a variety of electrolytes, macromolecules and different kinds of cells. This paper established a relative dielectric model of blood to explore the dielectric properties of biological tissue, the results show that characteristics of blood is vary with frequency and its composition, and the study could be a theoretical basis for further study on electrical properties of biological tissue.

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Canicattì, Eliana, Nunzia Fontana, Sami Barmada, and Agostino Monorchio. "Open-Ended Coaxial Probe for Effective Reconstruction of Biopsy-Excised Tissues’ Dielectric Properties." Sensors 24, no. 7 (2024): 2160. http://dx.doi.org/10.3390/s24072160.

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Dielectric characterization is extremely promising in medical contexts because it offers insights into the electromagnetic properties of biological tissues for the diagnosis of tumor diseases. This study introduces a promising approach to improve accuracy in the dielectric characterization of millimeter-sized biopsies based on the use of a customized electromagnetic characterization system by adopting a coated open-ended coaxial probe. Our approach aims to accelerate biopsy analysis without sample manipulation. Through comprehensive numerical simulations and experiments, we evaluated the effectiveness of a metal-coating system in comparison to a dielectric coating with the aim for replicating a real scenario: the use of a needle biopsy core with the tissue inside. The numerical analyses highlighted a substantial improvement in the reconstruction of the dielectric properties, particularly in managing the electric field distribution and mitigating fringing field effects. Experimental validation using bovine liver samples revealed highly accurate measurements, particularly in the real part of the permittivity, showing errors lower than 1% compared to the existing literature data. These results represent a significant advancement for the dielectric characterization of biopsy specimens in a rapid, precise, and non-invasive manner. This study underscores the robustness and reliability of our innovative approach, demonstrating the convergence of numerical analyses and empirical validation.

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Orkaa, M. Stephen, Aisha Ademoh Bello, Joseph Zira Dlama, and Ulu Jamus Ewuga. "Evaluating the Dielectric Characteristics of Tissues: A Relationship Between Low Frequency Range and Dryness." Nigerian Journal of Physics 33, no. 2 (2024): 146–56. http://dx.doi.org/10.62292/njp.v33i2.2024.229.

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The electromagnetic modeling of the human body requires basic parameters, which are characteristics of biological tissues. This review aims at assessing the dielectric characteristics of tissues at varying frequency, temperature and noting the dehydration effect. Using the Patient, Intervention, Comparison, Outcome: PICO as an evidence base practice formula, the review question, “Will exposure to low frequency electromagnetic fields modify the dielectric characteristics of tissues with moisture content much from those that are not exposed?” was broken into key concepts to aid in the search for articles. Findings about the dielectric properties of biological tissues were investigated, taking into account a number of pertinent factors such as the tissues under examination, their temperature, their frequency range, and their level of dryness. Using search engines like Google Scholar, Research Gate, and Science Direct, a preferred reporting item for systematic reviews and meta-analyses (PRISMA) flow chart illustrates how publications within the last two decades plus were found and reviewed. The review's findings highlighted several of the study's weaknesses, including the dehydration effect; scant or not reported and the frequency, where there has been less research conducted at lower frequencies. It was also observed that a low database on dielectric characteristics was typically present in some tissues, regardless of their sensitivity level. Lastly, research that is critical to the development of human body modeling in the future is reviewed

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Duta, Liviu, and Valentina Grumezescu. "The Effect of Doping on the Electrical and Dielectric Properties of Hydroxyapatite for Medical Applications: From Powders to Thin Films." Materials 17, no. 3 (2024): 640. http://dx.doi.org/10.3390/ma17030640.

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Recently, the favorable electrical properties of biomaterials have been acknowledged as crucial for various medical applications, including both bone healing and growth processes. This review will specifically concentrate on calcium phosphate (CaP)-based bioceramics, with a notable emphasis on hydroxyapatite (HA), among the diverse range of synthetic biomaterials. HA is currently the subject of extensive research in the medical field, particularly in dentistry and orthopedics. The existing literature encompasses numerous studies exploring the physical–chemical, mechanical, and biological properties of HA-based materials produced in various forms (i.e., powders, pellets, and/or thin films) using various physical and chemical vapor deposition techniques. In comparison, there is a relative scarcity of research on the electrical and dielectric properties of HA, which have been demonstrated to be essential for understanding dipole polarization and surface charge. It is noteworthy that these electrical and dielectric properties also offer valuable insights into the structure and functioning of biological tissues and cells. In this respect, electrical impedance studies on living tissues have been performed to assess the condition of cell membranes and estimate cell shape and size. The need to fill the gap and correlate the physical–chemical, mechanical, and biological characteristics with the electrical and dielectric properties could represent a step forward in providing new avenues for the development of the next-generation of high-performance HA-doped biomaterials for future top medical applications. Therefore, this review focuses on the electrical and dielectric properties of HA-based biomaterials, covering a range from powders and pellets to thin films, with a particular emphasis on the impact of the various dopants used. Therefore, it will be revealed that each dopant possesses unique properties capable of enhancing the overall characteristics of the produced structures. Considering that the electrical and dielectric properties of HA-based biomaterials have not been extensively explored thus far, the aim of this review is to compile and thoroughly discuss the latest research findings in the field, with special attention given to biomedical applications.

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Gabriel, Camelia. "Dielectric properties of biological tissue: Variation with age." Bioelectromagnetics 26, S7 (2005): S12—S18. http://dx.doi.org/10.1002/bem.20147.

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Zimmermann, Julius, and Ursula van Rienen. "Ambiguity in the interpretation of the low-frequency dielectric properties of biological tissues." Bioelectrochemistry 140 (August 2021): 107773. http://dx.doi.org/10.1016/j.bioelechem.2021.107773.

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Asami, Koji. "Dielectric properties of biological tissues in which cells are connected by communicating junctions." Journal of Physics D: Applied Physics 40, no. 12 (2007): 3718–27. http://dx.doi.org/10.1088/0022-3727/40/12/027.

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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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Ištuk, Niko, Emily Porter, Declan O’Loughlin, et al. "Dielectric Properties of Ovine Heart at Microwave Frequencies." Diagnostics 11, no. 3 (2021): 531. http://dx.doi.org/10.3390/diagnostics11030531.

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Accurate knowledge of the dielectric properties of biological tissues is important in dosimetry studies and for medical diagnostic, monitoring and therapeutic technologies. In particular, the dielectric properties of the heart are used in numerical simulations of radiofrequency and microwave heart ablation. In one recent study, it was demonstrated that the dielectric properties of different components of the heart can vary considerably, contrary to previous literature that treated the heart as a homogeneous organ with measurements that ignored the anatomical location. Therefore, in this study, we record and report the dielectric properties of the heart as a heterogeneous organ. We measured the dielectric properties at different locations inside and outside of the heart over the 500 MHz to 20 GHz frequency range. Different parts of the heart were identified based on the anatomy of the heart and their function; they include the epicardium, endocardium, myocardium, exterior and interior surfaces of atrial appendage, and the luminal surface of the great vessels. The measured dielectric properties for each part of the heart are reported at both a single frequency (2.4 GHz), which is of interest in microwave medical applications, and as parameters of a broadband Debye model. The results show that in terms of dielectric properties, different parts of the heart should not be considered the same, with more than 25% difference in dielectric properties between some parts. The specific Debye models and single frequency dielectric properties from this study can be used to develop more detailed models of the heart to be used in electromagnetic modeling.

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Yanenko, Oleksiy, Kostiantyn Shevchenko, Oleksandra Golovchanska, and Vasyl Symonenko. "ELECTROMAGNETIC PROPERTIES OF CEMENTS FOR FIXATION OF ORTHOPEDIC CONSTRUCTIONS." Bulletin of Kyiv Polytechnic Institute. Series Instrument Making, no. 66(2) (December 27, 2023): 100–104. http://dx.doi.org/10.20535/1970.66(2).2023.295057.

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Introduction. In practical dentistry, a significant number of various materials are used - for filling teeth, for implant restorative surgery, as well as materials for prosthetics. In this case, metals, dielectrics and their combinations are used. The article is devoted to the results of the study of electromagnetic properties of a group of dental materials - fixing cements, which belong to dielectric materials. Theoretical and experimental studies of EMC materials from the arsenal of maxillofacial reconstructive and restorative surgery were also conducted. Significant EMC deviations were detected in some materials. Scientific results of experimental studies and relevant recommendations are presented in a number of authors publications both in Ukraine and abroadMain purpose of this study. Usually, the orthopedic constructions and the fixation cement are in physical contact with both the patient's hard and soft tissues. Since dielectric materials at a human body temperature of 310K form their own electromagnetic radiation (EMR), it is important to ensure their electromagnetic compatibility - the coincidence of EMR with biological tissues adjacent to the implant to exclude the appearance of complications during their long-term use. A highly sensitive (10-14 W) microwave radiometric system was used for the measurements. In process of research, the five most commonly used cement samples in orthopedics were studied. Therefore, the purpose of this study is to determine the radiative capacity of cement as a material widely used in dental practice and to evaluate their level of electromagnetic compatibility with contacting biological tissues.Conclusions. 1. In the process of experimental and computational studies, the emissivity coefficients βM of 5 cement samples were determined, which range from 0.13 to 0.63 units.1.2. The first three samples (№№ 3-5) have a high level of electromagnetic compatibility (60...98 %), samples (№№ 6, 7) show much less coincidence with the EMR of the human body.3. The results of the conducted research can be used by orthopedic specialists to select materials with greater electromagnetic compatibility.

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Aouabdia, N., N. E. Belhadj-Tahar, and Georges Alquié. "Dielectric Properties Measurement of Biological Materials Using Non-Destructive Sensors." International Journal of Measurement Technologies and Instrumentation Engineering 5, no. 1 (2015): 46–56. http://dx.doi.org/10.4018/ijmtie.2015010104.

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The authors' research work has for objective the study of a sensor with planar resonator for applications in the non-destructive control. In this context, two approaches were defined. In a first part, a conception, a modeling, a simulation with commercial software (HFSS, CST), a realization and measurements were treated on Rectangular Patch Resonators (RPR). The proposed theoretical analysis is based on the Moment Method (MoM) via the Galerkin's approach, in which three types of entire domain basis functions are used to expand the patch currents. While, the first two types of basic functions involve a set of sinusoidal cavity modes without edge conditions (sbf-wo-ec) and with edge conditions (sbf-w-ec), and in order to incorporate the edge conditions (cp-ec), the third one consists of Chebyshev polynomials combinations with weighting factors. These last ones as well as the Green Dyadic spectral functions are efficiently implanted with compact Fortran 90 codes. Two EM commercial software HFSS and CST was used to validate the proposed RPR prototypes. The exactness of the obtained results is estimated using four prototypes operating near 6 GHz, taking into account only the fundamental mode resonant frequency. The theoretical model is compared with the simulations and the measurement results. The second approach of the authors' work which is developed in this paper is focused on the characterization of biological materials in vitro using the RPR prototypes proposed as applicator in the non-destructive control and the medical domain to find the abnormalities of these tissues such as: eczema, psoriasis, cancer, etc. The authors' center of interest will be managed towards the dielectric properties of the biological material to extract the relative permittivity and the loss factor on several samples (liver, fat, chicken, butter, foie gras, etc.).

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Li, Gun. "Electrical Properties Measurement of Rat Blood in 10 kHz-10 MHz." Advanced Materials Research 774-776 (September 2013): 836–39. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.836.

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Electromagnetic property of biological tissue is a critical issue for studying the biological effects of electromagnetic fields. In order to investigate the electrical parameters of rat blood and dispersion spectrum within the low-frequency, dielectric and conductivity parameters of rat blood was measured via HP4275A Multi Frequency LCR Meter in low frequency range (10 kHz-10 MHz), dispersive characteristics of blood electrical parameters was defined within the low-frequency. Dielectric properties of the measurement were used to compare with the theory of Cole-Cole fitting, and the fitting result shows that the Cole-Cole theory can well reflect the dielectric dispersion characteristics of rat blood. These results can be used to studying further biological effects of different frequencies electromagnetic fields.

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Aydinalp, Cemanur, Sulayman Joof, and Tuba Yilmaz. "Towards Non-Invasive Diagnosis of Skin Cancer: Sensing Depth Investigation of Open-Ended Coaxial Probes." Sensors 21, no. 4 (2021): 1319. http://dx.doi.org/10.3390/s21041319.

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Dielectric properties of biological tissues are traditionally measured with open-ended coaxial probes. Despite being commercially available for laboratory use, the technique suffers from high measurement error. This prevents the practical applications of the open-ended coaxial probes. One such application is the utilization of the technique for skin cancer detection. To enable a diagnostic tool, there is a need to address the error sources. Among others, tissue heterogeneity is a major contributor to measurement error. The effect of tissue heterogeneity on measurement accuracy can be decreased by quantifying the probe sensing depth. To this end, this work (1) investigates the sensing depth of the 2.2 mm-diameter open-ended coaxial probe for skin mimicking material and (2) offers a simple experimental setup and protocol for sensing depth characterization of open-ended coaxial probes. The sensing depth characterized through simulation and experiments using two double-layered configurations composed to mimic the skin tissue heterogeneity. Three thresholds in percent increase of dielectric property measurements were chosen to determine the sensing depth. Based on the experiment results, it was concluded that the sensing depth was effected by the dielectric property contrast between the layers. That is, high contrast results in rapid change whereas low contrast results in a slower change in measured dielectric properties. It was also concluded that the sensing depth was independent of frequency between 0.5 to 6 GHz and was mostly determined by the material located immediately at the aperture of the probe.

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Salahuddin, Saqib, Emily Porter, Finn Krewer, and Martin O’ Halloran. "Optimised analytical models of the dielectric properties of biological tissue." Medical Engineering & Physics 43 (May 2017): 103–11. http://dx.doi.org/10.1016/j.medengphy.2017.01.017.

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Hauser, A., and J. L. Verhey. "Simulation of cochlea implant stimulation considering dispersive properties of the environment." Journal of Applied Physics 131, no. 14 (2022): 144701. http://dx.doi.org/10.1063/5.0085776.

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A computer numeric algorithm is used to simulate the time course of the electric field around a stimulating electrode of a cochlear implant. The dispersive properties of the surrounding biological tissues, i.e., the frequency-dependent conductivity and dielectric properties, are considered in the simulations. The study focuses on the polarization of auditory nerve tissue. It investigates how the polarization changes with pulse shapes that are typically used in cochlear implants. It is shown that several findings on the effect of pulse shape on the threshold and dynamic range can be predicted on the basis of the mean amount of this polarization. This approach also provides a possible explanation for why a change from a biphasic to triphasic pulse is able to reduce unwanted facial costimulation, which is sometimes observed in cochlear implant users.

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Kyber, J., H. Hansgen, and F. Pliquett. "Dielectric properties of biological tissue at low temperatures demonstrated on fatty tissue." Physics in Medicine and Biology 37, no. 8 (1992): 1675–88. http://dx.doi.org/10.1088/0031-9155/37/8/004.

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Marchal, C., M. Nadi, A. J. Tosser, C. Roussey, and M. L. Gaulard. "Dielectric properties of gelatine phantoms used for simulations of biological tissues between 10 and 50 MHz." International Journal of Hyperthermia 5, no. 6 (1989): 725–32. http://dx.doi.org/10.3109/02656738909140497.

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Mohammed, Beadaa, Konstanty Bialkowski, Amin Abbosh, Paul C. Mills, and Andrew P. Bradley. "Closed-form equation to estimate the dielectric properties of biological tissues as a function of age." Bioelectromagnetics 38, no. 6 (2017): 474–81. http://dx.doi.org/10.1002/bem.22054.

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Rossmanna, Christian, and Dieter Haemmerich. "Review of Temperature Dependence of Thermal Properties, Dielectric Properties, and Perfusion of Biological Tissues at Hyperthermic and Ablation Temperatures." Critical Reviews in Biomedical Engineering 42, no. 6 (2014): 467–92. http://dx.doi.org/10.1615/critrevbiomedeng.2015012486.

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Martusevich, A. K., A. G. Galka, E. S. Golygina, and A. S. Fedotova. "Metabolic and radiofrequency features of reactive oxygen species and nitric oxide effects on biological tissue ex vivo." Fundamental and Clinical Medicine 6, no. 3 (2021): 8–14. http://dx.doi.org/10.23946/2500-0764-2021-6-3-8-14.

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Aim. To assess the effects of reactive oxygen species and nitric oxide on the scar tissue ex vivo.Materials and Methods. The study was performed using fragments of scar tissue (n = 10) removed intraoperatively in patients with Dupuytren's contracture. Each fragment was divided into 3 equal segments: 1) control; 2) treated with singlet oxygen for 5 minutes; 3) treated with nitric oxide (20 ppm) for 5 minutes. Upon the indicated treatment, we evaluated the dielectric properties of the tissue employing nearfield resonant microwave sensing using a customised software package (Institute of Applied Physics, Russian Academy of Sciences). Then, each segment was homogenised and the parameters of oxidative metabolism (intensity of free radical oxidation and total antioxidant activity) were measured in homogenates by Fe-induced biochemiluminescence.Results. Treatment of scar tissue fragments by singlet oxygen and nitric oxide altered the dielectric properties of the tissue and the intensity of free radical oxidation. Singlet oxygen action moderately increased the dielectric permittivity of the tissue and rendered a balanced stimulating effect on proand antioxidant systems. Nitric oxide significantly augmented dielectric permittivity and conductivity and raised the antioxidant potential of the tissue.

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Paffi, Alessandra, Francesca Apollonio, Micaela Liberti, Asher Sheppard, Giorgi Bit-Babik, and Quirino Balzano. "Culture Medium Geometry: The Dominant Factor Affecting In Vitro RF Exposure Dosimetry." International Journal of Antennas and Propagation 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/438962.

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Biological experiments that expose living cells or tissues to RF energy must have an aqueous medium to provide essential water, ions, nutrients, and growth factors. However, as we show here, the medium inherently functions as a receiving antenna that conveys RF energy to the biological entity in a manner entirely determined by exposure vessel geometry, orientation to the incident RF flux, frequency, and dielectric properties of the medium. We show for two common experimental arrangements that basic antenna theory can predict electromagnetic energy patterns that agree well with those otherwise obtained by computationally intensive methods that require specialized resources.

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Dipa, Safia Aktar, Muralee Monohara Pramanik, Mamun Rabbani, and Muhammad Abdul Kadir. "Effects of temperature on electrical impedance of biological tissues: ex-vivo measurements." Journal of Electrical Bioimpedance 15, no. 1 (2024): 116–24. http://dx.doi.org/10.2478/joeb-2024-0013.

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Abstract Bioelectrical impedance techniques have been useful in various applications, including body composition analysis, impedance plethysmography, impedance cardiography, lung ventilation, perfusion, and tissue characterization. Electrical impedance methods have also been useful in characterizing different foods like meat, fruits, and beverages. However, the temperature of tissue samples can change their dielectric properties, affecting their impedance. This research investigated the effects of temperature on the impedance of various biological tissues over the frequency range of 10 Hz to 5 MHz. Freshly excised animal tissues (lamb, cow, chicken), fish, fruits, and plants were considered as biological samples. The samples were placed in a test cell and submerged in a water bath heated by a hot plate to vary the temperature. Impedance measurements were conducted using a bioimpedance spectrometer in 2 °C steps within the temperature range of 20 °C to 50 °C. Impedance values decreased with increased temperature across all measurement frequencies for all biological samples. Curve fitting indicated that impedance decreased linearly with temperature, with a mean correlation coefficient of 0.972 for all samples. For all biological samples under investigation, the relative impedance change ranged from −0.58% to −2.27% per °C, with a mean and standard deviation of (−1.42±0.34) %/°C. On average, animal samples exhibited a higher relative temperature coefficient of −1.56% per °C (±0.41) across the frequency range, compared to −1.31% per °C (±0.26) for fruit and vegetable samples. Additionally, the relative temperature coefficient values were generally higher at lower frequencies than at higher frequencies. The findings of this research can be valuable for studies or biomedical applications involving variable tissue temperatures.

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Maenhout, Gertjan, Tomislav Markovic, Ilja Ocket, and Bart Nauwelaers. "Effect of Open-Ended Coaxial Probe-to-Tissue Contact Pressure on Dielectric Measurements." Sensors 20, no. 7 (2020): 2060. http://dx.doi.org/10.3390/s20072060.

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Open-ended coaxial probes are widely used to gather dielectric properties of biological tissues. Due to the lack of an agreed data acquisition protocol, several environmental conditions can cause inaccuracies when comparing dielectric data. In this work, the effect of a different measurement probe-to-tissue contact pressure was monitored in the frequency range from 0.5 to 20 GHz. Therefore, we constructed a controlled lifting platform with an integrated pressure sensor to exert a constant pressure on the tissue sample during the dielectric measurement. In the pressure range from 7.74 kPa to 77.4 kPa, we observed a linear correlation of − 0.31 ± 0.09 % and − 0.32 ± 0.14 % per kPa for, respectively, the relative real and imaginary complex permittivity. These values are statistically significant compared with the reported measurement uncertainty. Following the literature in different biology-related disciplines regarding pressure-induced variability in measurements, we hypothesize that these changes originate from squeezing out the interstitial and extracellular fluid. This process locally increases the concentration of membranes, cellular organelles, and proteins in the sensed volume. Finally, we suggest moving towards a standardized probe-to-tissue contact pressure, since the literature has already demonstrated that reprobing at the same pressure can produce repeatable data within a 1% uncertainty interval.

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Amin, Bilal, Muhammad Riaz ur Rehman, Muhammad Farooq, et al. "Optimizing Cardiac Wireless Implant Communication: A Feasibility Study on Selecting the Frequency and Matching Medium." Sensors 23, no. 7 (2023): 3411. http://dx.doi.org/10.3390/s23073411.

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Cardiac wireless implantable medical devices (CWIMD) have brought a paradigm shift in monitoring and treating various cardiac conditions, including heart failure, arrhythmias, and hypertension. One of the key elements in CWIMD is the implant antenna which uses radio frequency (RF) technology to wirelessly communicate and transmit data to external devices. However, wireless communication with a deeply implanted antenna using RF can be challenging due to the significant loss of electromagnetic (EM) signal at the air–skin interface, and second, due to the propagation and reflection of EM waves from different tissue boundaries. The air–skin interface loss of the EM wave is pronounced due to the absence of a matching medium. This paper investigates the EM propagation losses in the human body and presents a choice of optimal frequency for the design of the cardiac implant antenna and the dielectric properties of the matching medium. First, the dielectric properties of all tissues present in the human thorax including skin, fat, muscle, cartilage, and heart are analyzed as a function of frequency to study the EM wave absorption at different frequencies. Second, the penetration of EM waves inside the biological tissues is analyzed as a function of frequency. Third, a transmission line (TL) formalism approach is adopted to examine the optimal frequency band for designing a cardiac implant antenna and the matching medium for the air–skin interface. Finally, experimental validation is performed at two ISM frequencies, 433 MHz and 915 MHz, selected from the optimal frequency band (0.4–1.5 GHz) suggested by our analytical investigation. For experimental validation, two off-the-shelf flexible dipole antennas operating at selected ISM frequencies were used. The numerical and experimental findings suggested that for the specific application of a cardiac implant with a penetration depth of 7–17 cm, the most effective frequency range for operation is within 0.4–1.5 GHz. The findings based on the dielectric properties of thorax tissues, the penetration depth of EM waves, and the optimal frequency band have provided valuable information on developing and optimizing CWIMDs for cardiac care applications.

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Gabriel, S., R. W. Lau, and C. Gabriel. "The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz." Physics in Medicine and Biology 41, no. 11 (1996): 2251–69. http://dx.doi.org/10.1088/0031-9155/41/11/002.

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Smolyanskaya, O. A., N. V. Chernomyrdin, A. A. Konovko, et al. "Terahertz biophotonics as a tool for studies of dielectric and spectral properties of biological tissues and liquids." Progress in Quantum Electronics 62 (November 2018): 1–77. http://dx.doi.org/10.1016/j.pquantelec.2018.10.001.

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Katti, Kalpana S., Daniel Frech, Maoxu Qian, and Mehmet Sarikaya. "Local Dielectric Function Of Biogenic and Geological Polymorphs of CaCO3 Via Transmission Eels." Microscopy and Microanalysis 4, S2 (1998): 782–83. http://dx.doi.org/10.1017/s143192760002403x.

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This paper focuses on the differences of physical properties, specifically local dielectric function, of biogenic and geological mineral CaCO3. The goal is to assess the role of organism in forming biogenic inorganic materials. Local dielectric functions of biogenic and geological minerals were determined by transmission electron energy loss spectroscopy using a previously developed strategy.Previous work on microstructural characterization of biological hard tissues, e.g., abalone shells, has shown variations in terms of defects, morphology, crystallography, and organization of nano- and microstructures in two biological polymorphs of calcium carbonate, calcite and aragonite, in the prismatic and nacreous regions, respectively. In the abalone, the outer (1-5 mm thick) region of the shell is composed of calcite crystallites (1-5 μm diameter) with columnar organization perpendicular to shell plane. On the inner region, 1-10 mm thick nacre is composed of aragonite crystallites (0.5 μm thick and 5 -10 μm edge-length) forming flat platelets, parallel to the shell plane.

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Bohuslávek, Zdeněk. "The measurement method of meat conductivity." Czech Journal of Food Sciences 36, No. 5 (2018): 372–77. http://dx.doi.org/10.17221/164/2018-cjfs.

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This paper analyses the properties of electrode methods and contactless inductive methods of the conductivity measurement of biological tissue, which are one of the few which are able to measure the potentials of corresponding components of complex conductivity, i.e. the real reactive conductivity of a resistive and an imaginary component. The analysis was performed by computer modelling and experimental measurements. The publication describes the modelling of currents and of the potential by electrode and methods on tissue phantoms using the finite element method. The Comsol Multiphysics v3.4 program was used for the calculations. The results are presented in 2D and 3D diagrams. Experimental measurements with electrodes in phantom tissues with different conductivity were also conducted and the components of the complex conductivity were evaluated with an RLC Bridge and most accurately by using a lock-in amplifier. Results and experience from the experiments will make it possible to proceed with the next phase of research focused on measuring conductivity and dielectric properties in different types of meat.

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Endo, Yuta, Yoshito Tezuka, Kazuyuki Saito, and Koichi Ito. "Dielectric properties and water contents of coagulated biological tissue by microwave heating." IEICE Communications Express 4, no. 4 (2015): 105–10. http://dx.doi.org/10.1587/comex.4.105.

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Wang, Hang, Yong He, Qingguo Yan, et al. "Correlation between the dielectric properties and biological activities of humanex vivohepatic tissue." Physics in Medicine and Biology 60, no. 6 (2015): 2603–17. http://dx.doi.org/10.1088/0031-9155/60/6/2603.

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Matković, Anđela, Anton Kordić, Antonia Jakovčević, and Antonio Šarolić. "Complex Permittivity of Ex-Vivo Human, Bovine and Porcine Brain Tissues in the Microwave Frequency Range." Diagnostics 12, no. 11 (2022): 2580. http://dx.doi.org/10.3390/diagnostics12112580.

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Accurate knowledge about the dielectric properties of biological tissues in the microwave frequency range may lead to advancement of biomedical applications based on microwave technology. However, the published data are very scarce, especially for human brain tissues. The aim of this work was to measure and report the complex permittivity of brain white matter, grey matter and cerebellum. Complex permittivity was measured on human, bovine and porcine brain tissues in the microwave frequency range from 0.5 to 18 GHz using an open-ended coaxial probe. The results present a valuable addition to the available data on the brain tissue complex permittivity. Some noticeable variations between the results lead to several conclusions. Complex permittivity variation within the same tissue type of the individual species was comparable to interspecies variation. The difference was prominent between human brains obtained from autopsies, while bovine brains obtained from healthy animals showed very similar complex permittivity. We hypothesize that the difference might have been caused by the basic pathologies of the patients, where the associated therapies could have affected the brain water content. We also examined the effect of excised tissue degradation on its complex permittivity over the course of three days, and the results suggest the gradual dehydration of the samples.

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

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