1
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Li K, Hikage T, Masuda H, Ijima E, Nagai A, Taguchi K. Parameter variation effects on millimeter wave dosimetry based on precise skin thickness in real rats. Sci Rep 2023; 13:17397. [PMID: 37833400 PMCID: PMC10575911 DOI: 10.1038/s41598-023-44572-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 10/10/2023] [Indexed: 10/15/2023] Open
Abstract
This study presents a parametric analysis of the steady-state temperature elevation in rat skin models due to millimeter wave exposure at frequencies from 6-100 GHz. The statistical data of the thickness of skin layers, namely epidermis, dermis, dermal white adipose tissue, and panniculus carnosus, were measured for the first time using the excised tissues of real male Sprague-Dawley rats. Based on the precise structure obtained from the histological analysis of rat skin, we solve the bioheat transfer equation to investigate the effects of changes in parameters, such as body parts and thermal constants, on the absorbed power density and temperature elevation of biological tissues. Owing to the notably thin dermal white adipose tissue layer, the surface temperature elevation in the rat head and dorsal skin at 6-100 GHz is 52.6-32.3% and 83.3-58.8% of the average values of different human skin models, respectively. Our results also reveal that the surface temperature elevation of rat skin may correlate with the tissue thickness and deep blood perfusion rates.
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Affiliation(s)
- Kun Li
- Advanced Wireless and Communication Research Center, The University of Electro-Communications, 182-8585, Tokyo, Japan.
| | - Takashi Hikage
- Faculty of Information Science and Technology, Hokkaido University, 060-0808, Hokkaido, Japan
| | - Hiroshi Masuda
- Department of Environmental Medicine, Kurume University School of Medicine, Fukuoka, 830-0011, Japan
| | - Etsuko Ijima
- Department of Environmental Medicine, Kurume University School of Medicine, Fukuoka, 830-0011, Japan
| | - Akiko Nagai
- Department of Anatomy, Aichi-Gakuin University School of Dentistry, Nagoya, 464-8650, Japan
| | - Kenji Taguchi
- Department of Electrical and Electronic Engineering, Kitami Institute of Technology, Kitami, 090-8507, Japan
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2
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Kapetanović A, Poljak D. Machine learning-assisted antenna modelling for realistic assessment of incident power density on non-planar surfaces above 6 GHz. RADIATION PROTECTION DOSIMETRY 2023; 199:826-834. [PMID: 37225223 DOI: 10.1093/rpd/ncad114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this paper, the analysis of exposure reference levels is performed for the case of a half-wavelength dipole antenna positioned in the immediate vicinity of non-planar body parts. The incident power density (IPD) spatially averaged over the spherical and cylindrical surface is computed at the 6-90 GHz range, and subsequently placed in the context of the current international guidelines and standards for limiting exposure to electromagnetic (EM) fields which are defined considering planar computational tissue models. As numerical errors are ubiquitous at such high frequencies, the spatial resolution of EM models needs to be increased which in turn results in increased computational complexity and memory requirements. To alleviate this issue, we hybridise machine learning and traditional scientific computing approaches through differentiable programming paradigm. Findings demonstrate a strong positive effect the curvature of non-planar models has on the spatially averaged IPD with up to 15% larger values compared to the corresponding planar model in considered exposure scenarios.
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Affiliation(s)
- Ante Kapetanović
- Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), University of Split, R. Boškovića 32, 21000 Split, Croatia
| | - Dragan Poljak
- Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), University of Split, R. Boškovića 32, 21000 Split, Croatia
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3
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Christ A, Fallahi A, Neufeld E, Balzano Q, Kuster N. Mechanism of Capacitive Coupling of Proximal Electromagnetic Sources With Biological Bodies. Bioelectromagnetics 2022; 43:404-412. [DOI: 10.1002/bem.22422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/28/2022] [Accepted: 09/10/2022] [Indexed: 11/08/2022]
Affiliation(s)
| | - Arya Fallahi
- IT'IS Foundation Zürich Switzerland
- Swiss Federal Institute of Technology Zürich Switzerland
| | | | | | - Niels Kuster
- IT'IS Foundation Zürich Switzerland
- Swiss Federal Institute of Technology Zürich Switzerland
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4
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Li K, Sasaki K. Monte Carlo Simulation of Clothed Skin Exposure to Electromagnetic Field With Oblique Incidence Angles at 60 GHz. Front Public Health 2022; 10:795414. [PMID: 35237549 PMCID: PMC8882740 DOI: 10.3389/fpubh.2022.795414] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/07/2022] [Indexed: 12/23/2022] Open
Abstract
This study presents an investigation of clothed human skin exposure to obliquely incident electromagnetic waves at 60 GHz. We clarified the combined impacts of the cloth material, incidence angle, and polarization on the assessment of transmittance and absorbed power density (APD) at the skin surface. A Monte Carlo simulation was conducted considering the thickness variation of the cloth material and skin tissue. For the case of transverse magnetic™ wave exposure, the transmittance increases with increasing incident angle up to the maximum transmittance angle in the range from 60 to 80°, which is known as the Brewster effects, regardless of textile materials and air gap between cloth and skin. The air gap results in a periodic fluctuation of the APD, where the variation is almost within 1 dB when the incident power density is constant and the incident angle is smaller than 40°. Our results also show that as the air gap increases to 2.5 mm, i.e., half-wavelength at 60 GHz in the air, the APD within the skin surface covered by typical cloth materials increases up to 40% compared with that of bare skin. Although the use of several cloth materials may increase the transmittance and APD in oblique incidence scenarios, all the results of the APD do not exceed the basic restriction for local exposure, demonstrating that the current guidelines for human exposure to electromagnetic fields are appropriate for preventing the excessive exposure at 60 GHz considering the impacts of oblique incidence angles and cloth materials.
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Affiliation(s)
- Kun Li
- Faculty of Engineering and Design, Kagawa University, Takamatsu, Japan
- *Correspondence: Kun Li
| | - Kensuke Sasaki
- Radio Research Institute, National Institute of Information and Communications Technology, Koganei, Japan
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5
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Assessment of Human Exposure Levels Due to Mobile Phone Antennas in 5G Networks. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19031546. [PMID: 35162566 PMCID: PMC8835459 DOI: 10.3390/ijerph19031546] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/25/2022] [Accepted: 01/28/2022] [Indexed: 02/05/2023]
Abstract
The recent deployment of 5G networks is bringing benefits to the population but it is also raising public concern about human RF-EMF exposure levels. This is particularly relevant considering the next 5G mobile devices, which are placed in close proximity to the subjects. Therefore, the aim of the following paper is focused on expanding the knowledge of the exposure levels in 5G exposure scenarios, specifically for mobile applications, using computational methods. The mobile antenna was designed considering the 5G technology innovations (i.e., mm-wave spectrum, beamforming capability, high gain and wide coverage), resulting in a phased-array antenna with eight elements at the working frequency of 27 GHz. To assess the exposure levels, different types of skin models with different grades of details and layers were considered. Furthermore, not only was the presence of a mobile phone user simulated, but also that of a person in their proximity, who could be hit by the main beam of the phased-array antenna. All the simulations were conducted in Sim4Life platform, where the exposure levels were assessed in terms of absorbed power density averaged over 4 cm2 and 1 cm2, following the ICNIRP guidelines. The results highlighted that the use of the homogeneous skin model led to the absorbed power density peaks being greatly underestimated, with respect to those obtained in multilayer skin models. Furthermore, interestingly, we found that the exposure levels obtained for the person passing nearby were slightly higher than those experienced by the mobile phone user himself. Finally, using the allowed input power for real mobile applications, all the values remained below the limits indicated by the ICNIRP guidelines.
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Cherkasova OP, Serdyukov DS, Nemova EF, Ratushnyak AS, Kucheryavenko AS, Dolganova IN, Xu G, Skorobogatiy M, Reshetov IV, Timashev PS, Spektor IE, Zaytsev KI, Tuchin VV. Cellular effects of terahertz waves. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210179VR. [PMID: 34595886 PMCID: PMC8483303 DOI: 10.1117/1.jbo.26.9.090902] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/08/2021] [Indexed: 05/15/2023]
Abstract
SIGNIFICANCE An increasing interest in the area of biological effects at exposure of tissues and cells to the terahertz (THz) radiation is driven by a rapid progress in THz biophotonics, observed during the past decades. Despite the attractiveness of THz technology for medical diagnosis and therapy, there is still quite limited knowledge about safe limits of THz exposure. Different modes of THz exposure of tissues and cells, including continuous-wave versus pulsed radiation, various powers, and number and duration of exposure cycles, ought to be systematically studied. AIM We provide an overview of recent research results in the area of biological effects at exposure of tissues and cells to THz waves. APPROACH We start with a brief overview of general features of the THz-wave-tissue interactions, as well as modern THz emitters, with an emphasis on those that are reliable for studying the biological effects of THz waves. Then, we consider three levels of biological system organization, at which the exposure effects are considered: (i) solutions of biological molecules; (ii) cultures of cells, individual cells, and cell structures; and (iii) entire organs or organisms; special attention is devoted to the cellular level. We distinguish thermal and nonthermal mechanisms of THz-wave-cell interactions and discuss a problem of adequate estimation of the THz biological effects' specificity. The problem of experimental data reproducibility, caused by rareness of the THz experimental setups and an absence of unitary protocols, is also considered. RESULTS The summarized data demonstrate the current stage of the research activity and knowledge about the THz exposure on living objects. CONCLUSIONS This review helps the biomedical optics community to summarize up-to-date knowledge in the area of cell exposure to THz radiation, and paves the ways for the development of THz safety standards and THz therapeutic applications.
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Affiliation(s)
- Olga P. Cherkasova
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
- Novosibirsk State Technical University, Russian Federation
| | - Danil S. Serdyukov
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
- Federal Research Center Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Eugenia F. Nemova
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Alexander S. Ratushnyak
- Institute of Computational Technologies of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Anna S. Kucheryavenko
- Institute of Solid State Physics of the Russian Academy of Sciences, Russian Federation
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
| | - Irina N. Dolganova
- Institute of Solid State Physics of the Russian Academy of Sciences, Russian Federation
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Sechenov University, World-Class Research Center “Digital Biodesign and Personalized Healthcare,” Russian Federation
| | - Guofu Xu
- Polytechnique Montreal, Department of Engineering Physics, Canada
| | | | - Igor V. Reshetov
- Sechenov University, Institute for Cluster Oncology, Russian Federation
- Academy of Postgraduate Education FSCC FMBA, Russian Federation
| | - Peter S. Timashev
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Sechenov University, World-Class Research Center “Digital Biodesign and Personalized Healthcare,” Russian Federation
- N.N. Semenov Institute of Chemical Physics, Department of Polymers and Composites, Russian Federation
- Lomonosov Moscow State University, Department of Chemistry, Russian Federation
| | - Igor E. Spektor
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
| | - Kirill I. Zaytsev
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Bauman Moscow State Technical University, Russian Federation
| | - Valery V. Tuchin
- Saratov State University, Russian Federation
- Institute of Precision Mechanics and Control of the Russian Academy of Sciences, Russian Federation
- National Research Tomsk State University, Russian Federation
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7
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Samaras T, Christ A, Kuster N. Compliance Assessment of the Epithelial or Absorbed Power Density Below 10 GHz Using SAR Measurement Systems. Bioelectromagnetics 2021; 42:484-490. [PMID: 34130354 DOI: 10.1002/bem.22355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 04/25/2021] [Accepted: 05/29/2021] [Indexed: 11/07/2022]
Abstract
The introduction of new dosimetric quantities, in particular, epithelial or absorbed power density for frequencies above 6 GHz, in exposure guidelines and safety standards requires the development of new experimental assessment procedures for compliance testing. In this study, we propose to approximate the peak spatial-average absorbed power density (psSab ) using the same measured data and algorithms that are used for determining the peak spatial-average specific absorption rate psSAR, which is currently limited to frequencies up to 10 GHz. The uncertainty component for the transformation of psSAR to psSab was evaluated as less than 0.55 dB (13.5%) for any source as close as 0.02 λ from the tissue simulating media. The approach is easy to implement and allows determining compliance with the basic restrictions of the latest safety guidelines. In the next project, we will expand dosimetric probes, phantoms, and procedures for frequencies above 10 GHz. © 2021 Bioelectromagnetics Society.
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Affiliation(s)
- Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece.,Department of Physics, University of Malta, Msida, Malta
| | - Andreas Christ
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland
| | - Niels Kuster
- Foundation for Research on Information Technologies in Society (IT'IS), Zurich, Switzerland.,Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
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8
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Hirata A, Kodera S, Sasaki K, Gomez-Tames J, Laakso I, Wood A, Watanabe S, Foster KR. Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies. Phys Med Biol 2021; 66. [PMID: 33761473 DOI: 10.1088/1361-6560/abf1b7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/24/2021] [Indexed: 11/11/2022]
Abstract
International guidelines/standards for human protection from electromagnetic fields have been revised recently, especially for frequencies above 6 GHz where new wireless communication systems have been deployed. Above this frequency a new physical quantity 'absorbed/epithelial power density' has been adopted as a dose metric. Then, the permissible level of external field strength/power density is derived for practical assessment. In addition, a new physical quantity, fluence or absorbed energy density, is introduced for protection from brief pulses (especially for shorter than 10 s). These limits were explicitly designed to avoid excessive increases in tissue temperature, based on electromagnetic and thermal modeling studies but supported by experimental data where available. This paper reviews the studies on the computational modeling/dosimetry which are related to the revision of the guidelines/standards. The comparisons with experimental data as well as an analytic solution are also been presented. Future research needs and additional comments on the revision will also be mentioned.
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Affiliation(s)
- Akimasa Hirata
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya Japan
| | - Sachiko Kodera
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Kensuke Sasaki
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Jose Gomez-Tames
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya Japan
| | - Ilkka Laakso
- Dept. of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Andrew Wood
- Swinburne University of Technology Melbourne, Melbourne, Australia
| | - Soichi Watanabe
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Kenneth R Foster
- University of Pennsylvania, Philadelphia, PA, United States of America
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9
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Age-dependence of electromagnetic power and heat deposition in near-surface tissues in emerging 5G bands. Sci Rep 2021; 11:3983. [PMID: 33597554 PMCID: PMC7889919 DOI: 10.1038/s41598-021-82458-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 12/07/2020] [Indexed: 12/03/2022] Open
Abstract
With the development of 5th generation (5G) mobile networks people of different ages will be exposed in the upper part of the microwave spectrum. From the perspective of non-ionizing radiation dosimetry, an accurate analysis of age-dependent electromagnetic power deposition and resulting heating is required. In this study, we evaluate the effect of age on exposure at 26 GHz and 60 GHz. A near-surface tissue model illuminated by a plane wave is used to asses the exposure considering both frequency-independent and frequency-dependent limits. The age-related variation of the skin thickness and tissue electromagnetic properties has been considered. Moreover, the blood flow decrease rate has been taken into account to assess the age-dependent heating. Our results demonstrate that the overall variations of the power density, specific absorption rate (SAR) and heating in the near-surface tissues are limited to about 10–15%. These variations are mainly due to the tissue permittivity and blood flow change with age. In contrast to the transmitted power density that increases with age, the peak SAR decreases at both frequencies. The peak steady-state heating increases from 5 to 70 years old by roughly 11% at 26 GHz and 13% at 60 GHz.
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Morelli MS, Gallucci S, Siervo B, Hartwig V. Numerical Analysis of Electromagnetic Field Exposure from 5G Mobile Communications at 28 GHZ in Adults and Children Users for Real-World Exposure Scenarios. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18031073. [PMID: 33530365 PMCID: PMC7908514 DOI: 10.3390/ijerph18031073] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/21/2021] [Accepted: 01/23/2021] [Indexed: 12/23/2022]
Abstract
The recent development of millimeter-wave (mmW) technologies, such as the fifth-generation (5G) network, comes with concerns related to user exposure. A quite large number of dosimetry studies above 6 GHz have been conducted, with the main purpose being to establish the correlation between different dosimetric parameters and the skin surface temperature elevation. However, the dosimetric studies from 28 GHz user equipment using different voxel models have not been comprehensively discussed yet. In this study, we used the finite-difference time-domain (FDTD) method for the estimation of the absorption of radiofrequency (RF) energy from a microstrip patch antenna array (28 GHz) in different human models. Specifically, we analyzed different exposure conditions simulating three real common scenarios (a phone call scenario, message writing scenario, and browsing scenario) regarding the use of smartphones/tablets by four different individuals (adult male and female, child male and female). From the results of Absorbed Power Density (Sab), it is possible to conclude that all the considered exposure scenarios comply with the safety limits, both for adult and children models. However, the high values of the local Specific Absorption Rate (SAR) in the superficial tissues and the slight differences in its distribution between adults and children suggest the need for further and more detailed analysis.
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Affiliation(s)
- Maria Sole Morelli
- U.O.C. Infotel, Fondazione Toscana Gabriele Monasterio, 56100 Pisa, Italy;
| | - Silvia Gallucci
- DIITET Department, Institute of Electronics and Information and Telecommunications Engineering IEIIT-CNR, 20133 Milan, Italy;
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, 20133 Milan, Italy
| | - Beatrice Siervo
- Department of Information Engineering, University of Pisa, 56100 Pisa, Italy;
| | - Valentina Hartwig
- DSB Department, Institute of Clinical Physiology IFC-CNR, 56100 Pisa, Italy
- Correspondence:
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Christ A, Samaras T, Neufeld E, Kuster N. TRANSMISSION COEFFICIENT OF POWER DENSITY INTO SKIN TISSUE BETWEEN 6 AND 300 GHZ. RADIATION PROTECTION DOSIMETRY 2020; 192:113-118. [PMID: 33270899 DOI: 10.1093/rpd/ncaa179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/08/2020] [Accepted: 10/12/2020] [Indexed: 06/12/2023]
Abstract
The latest electromagnetic safety guidelines define transmitted or epithelial power density as the basic restriction above 6 GHz. In this note, we derive an approximation for a conservative transmission coefficient for quasi plane wave incidence as a function of the frequency for the normal component of the Poynting vector with respect to the evaluation plane or tissue surface |Sz inc| and for its modulus ||Sinc||. The maximum transmission coefficient for the normal component of the Poynting vector ${\boldsymbol{T}}_{\mathbf{z}}^{\mathbf{max}}$ is 1 independent of tissue composition and frequency. Approximations of ${\boldsymbol{T}}_{\mathbf{total}}^{\mathbf{max}}$ normalized to ||Sinc|| for thin and thick stratum corneum are provided allowing higher exposures. These approximations allow to conservatively demonstrate compliance with basic restrictions when quasi plane-wave conditions are locally satisfied and enhancement effects of standing waves between source and body can be neglected. The reported results are important to regulators and standardization bodies regarding revisions of compliance requirements and safety guidelines.
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Affiliation(s)
- Andreas Christ
- IT'IS Foundation, Zeughausstr. 43, 8004 Zürich, Switzerland
| | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Esra Neufeld
- IT'IS Foundation, Zeughausstr. 43, 8004 Zürich, Switzerland
| | - Niels Kuster
- IT'IS Foundation, Zeughausstr. 43, 8004 Zürich, Switzerland
- Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland
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12
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Diao Y, Rashed EA, Hirata A. Assessment of absorbed power density and temperature rise for nonplanar body model under electromagnetic exposure above 6 GHz. Phys Med Biol 2020; 65:224001. [PMID: 33007761 DOI: 10.1088/1361-6560/abbdb7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The averaged absorbed power density (APD) and temperature rise in body models with nonplanar surfaces were computed for electromagnetic exposure above 6 GHz. Different calculation schemes for the averaged APD were investigated. Additionally, a novel compensation method for correcting the heat convection rate on the air/skin interface in voxel human models was proposed and validated. The compensation method can be easily incorporated into bioheat calculations and does not require information regarding the normal direction of the boundary voxels, in contrast to a previously proposed method. The APD and temperature rise were evaluated using models of a two-dimensional cylinder and a three-dimensional partial forearm. The heating factor, which was defined as the ratio of the temperature rise to the APD, was calculated using different APD averaging schemes. Our computational results revealed different frequency and curvature dependences. For body models with curvature radii of >30 mm and at frequencies of >20 GHz, the differences in the heating factors among the APD schemes were small.
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Affiliation(s)
- Yinliang Diao
- College of Electronic Engineering, South China Agricultural University, Guangzhou 510642, People's Republic of China. Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
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13
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Christ A, Samaras T, Neufeld E, Kuster N. RF-INDUCED TEMPERATURE INCREASE IN A STRATIFIED MODEL OF THE SKIN FOR PLANE-WAVE EXPOSURE AT 6-100 GHZ. RADIATION PROTECTION DOSIMETRY 2020; 188:350-360. [PMID: 31950182 DOI: 10.1093/rpd/ncz293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/11/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
This study assesses the maximum temperature increase induced by exposure to electromagnetic fields between 6 and 100 GHz using a stratified model of the skin with four or five layers under plane wave incidence. The skin model distinguishes the stratum corneum (SC) and the viable epidermis as the outermost layers of the skin. The analysis identifies the tissue layer structures that minimize reflection and maximize the temperature increase induced by the electromagnetic field. The maximum observed temperature increase is 0.4°C for exposure at the present power density limit for the general population of 10 W m -2 . This result is more than twice as high as the findings reported in a previous study. The reasons for this difference are identified as impedance matching effects in the SC and less conservative thermal parameters. Modeling the skin as homogeneous dermis tissue can underestimate the induced temperature increase by more than a factor of three.
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Affiliation(s)
| | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Niels Kuster
- IT'IS Foundation, Zürich, Switzerland
- Swiss Federal Institute of Technology (ETHZ), Zürich, Switzerland
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14
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Christ A, Samaras T, Neufeld E, Kuster N. Limitations of Incident Power Density as a Proxy for Induced Electromagnetic Fields. Bioelectromagnetics 2020; 41:348-359. [DOI: 10.1002/bem.22268] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 04/06/2020] [Accepted: 04/22/2020] [Indexed: 11/06/2022]
Affiliation(s)
| | - Theodoros Samaras
- Department of PhysicsAristotle University of ThessalonikiThessaloniki Greece
| | | | - Niels Kuster
- IT'IS FoundationZürich Switzerland
- Swiss Federal Institute of TechnologyZürich Switzerland
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