1
|
Bouisset N, Nissi J, Laakso I, Reynolds RF, Legros A. Is activation of the vestibular system by electromagnetic induction a possibility in an MRI context? Bioelectromagnetics 2024; 45:171-183. [PMID: 38348647 DOI: 10.1002/bem.22497] [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: 09/02/2023] [Revised: 11/21/2023] [Accepted: 12/16/2023] [Indexed: 04/17/2024]
Abstract
In recent years, an increasing number of studies have discussed the mechanisms of vestibular activation in strong magnetic field settings such as occur in a magnetic resonance imaging scanner environment. Amid the different hypotheses, the Lorentz force explanation currently stands out as the most plausible mechanism, as evidenced by activation of the vestibulo-ocular reflex. Other hypotheses have largely been discarded. Nonetheless, both human data and computational modeling suggest that electromagnetic induction could be a valid mechanism which may coexist alongside the Lorentz force. To further investigate the induction hypothesis, we provide, herein, a first of its kind dosimetric analysis to estimate the induced electric fields at the vestibular system and compare them with what galvanic vestibular stimulation would generate. We found that electric fields strengths from induction match galvanic vestibular stimulation strengths generating vestibular responses. This review examines the evidence in support of electromagnetic induction of vestibular responses, and whether movement-induced time-varying magnetic fields should be further considered and investigated.
Collapse
Affiliation(s)
- Nicolas Bouisset
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
| | - Janita Nissi
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Ilkka Laakso
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Raymond F Reynolds
- School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Alexandre Legros
- Human Threshold Research Group, Lawson Health Research Institute, London, Ontario, Canada
- School of Kinesiology, Western University, London, Ontario, Canada
- EuroMov Digital Health in Motion, Univ Montpellier, IMT Mines Ales, Montpellier, France
- Departments of Medical Biophysics and Medical Imaging Western University, London, Ontario, Canada
- Eurostim, Montpellier, France
| |
Collapse
|
2
|
Ahn J, Hong SE, Kim H, Song K, Choi HD, Ahn S. Improved Calculation Method of Coupling Factors for Low-Frequency Wireless Power Transfer Systems. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 19:44. [PMID: 35010303 PMCID: PMC8751195 DOI: 10.3390/ijerph19010044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
The concept of a coupling factor was introduced in International Electrotechnical Commission (IEC) 62311 and 62233 to provide a product safety assessment that considers the localized exposure when an electromagnetic field (EMF) source is close to the human body. To calculate the coupling factors between the human body and EMF source, a numerical calculation should be carried out to calculate the internal quantities of the human body models. However, at frequencies below 10 MHz, the computed current density or internal electric field has computational artifacts from segmentation or discretization errors. Specifically, coupling factors are calculated based on the maximum values, which may include computational artifacts due to abnormal peaks. In this study, we propose an improved calculation method to remove computational artifacts by applying the 99.99th percentile in calculating the coupling factors without underestimation. The performance of the proposed method is verified through a comparison based on various human body models with wireless power transfer (WPT) systems and compliance with the reference levels and basic restrictions. The results indicate that the proposed method can provide uniform coupling factors by reducing the computational errors by up to 65.3% compared to a conventional method.
Collapse
Affiliation(s)
- Jangyong Ahn
- The CCS Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34051, Korea; (J.A.); (H.K.); (K.S.)
| | - Seon-Eui Hong
- Radio and Satellite Research Division, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea; (S.-E.H.); (H.-D.C.)
| | - Haerim Kim
- The CCS Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34051, Korea; (J.A.); (H.K.); (K.S.)
| | - Kyunghwan Song
- The CCS Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34051, Korea; (J.A.); (H.K.); (K.S.)
| | - Hyung-Do Choi
- Radio and Satellite Research Division, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea; (S.-E.H.); (H.-D.C.)
| | - Seungyoung Ahn
- The CCS Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34051, Korea; (J.A.); (H.K.); (K.S.)
| |
Collapse
|
3
|
Colella M, Paffi A, De Santis V, Apollonio F, Liberti M. Effect of skin conductivity on the electric field induced by transcranial stimulation techniques in different head models. Phys Med Biol 2021; 66:035010. [PMID: 33496268 DOI: 10.1088/1361-6560/abcde7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study aims at quantifying the effect that using different skin conductivity values has on the estimation of the electric (E)-field distribution induced by transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in the brain of two anatomical models. The induced E-field was calculated with numerical simulations inside MIDA and Duke models, assigning to the skin a conductivity value estimated from a multi-layered skin model and three values taken from literature. The effect of skin conductivity variations on the local E-field induced by tDCS in the brain was up to 70%. In TMS, minor local differences, in the order of 20%, were obtained in regions of interest for the onset of possible side effects. Results suggested that an accurate model of the skin is necessary in all numerical studies that aim at precisely estimating the E-field induced during TMS and tDCS applications. This also highlights the importance of further experimental studies on human skin characterization, especially at low frequencies.
Collapse
Affiliation(s)
- Micol Colella
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Alessandra Paffi
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Valerio De Santis
- Department of Industrial and Information Engineering and Economics (DIIEE), University of L'Aquila, L'Aquila, Italy
| | - Francesca Apollonio
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| | - Micaela Liberti
- Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome 'La Sapienza', Rome, Italy
| |
Collapse
|
4
|
Soldati M, Murakami T, Laakso I. Inter-individual variations in electric fields induced in the brain by exposure to uniform magnetic fields at 50 Hz. Phys Med Biol 2020; 65:215006. [PMID: 32615544 DOI: 10.1088/1361-6560/aba21e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Institute of Electrical and Electronics Engineers (IEEE) standard establish safety limits for human exposure to electromagnetic fields. At low frequencies, only a limited number of computational body models or simplified geometrical shapes are used to relate the internal induced electric fields and the external magnetic fields. As a consequence, both standard/guidelines derive the exposure reference levels for the external magnetic field without considering the variability between individuals. Here we provide quantitative data on the variation of the maximum electric field strengths induced in the brain of 118 individuals when exposed to uniform magnetic fields at 50 Hz. We found that individual characteristics, such as age and skull volume, as well as incident magnetic field direction, have a systematic effect on the peak electric field values. Older individuals show higher induced electric field strengths, possibly due to age-related anatomical changes in brain. Peak electric field strengths are found to increase for larger skull volumes, as well as for incident magnetic fields directed along the lateral direction. Moreover, the maximum electric fields provided by the anatomical models used by ICNIRP for deriving exposure limits are considerably higher than those obtained here. On the contrary, the IEEE elliptical exposure model produces a weaker peak electric field strength. Our findings are useful for the revision and harmonization of the current exposure standard and guidelines. The present investigation reduces the dosimetric uncertainty of the induced electric field among different anatomical induction models. The obtained results can be used as a basis for the selection of appropriate reduction factors when deriving exposure reference levels for human protection to low-frequency electromagnetic exposure.
Collapse
Affiliation(s)
- Marco Soldati
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | | | | |
Collapse
|
5
|
Soldati M, Laakso I. Computational errors of the induced electric field in voxelized and tetrahedral anatomical head models exposed to spatially uniform and localized magnetic fields. ACTA ACUST UNITED AC 2020; 65:015001. [DOI: 10.1088/1361-6560/ab5dfb] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
6
|
Impact of extremely low-frequency magnetic fields on human postural control. Exp Brain Res 2018; 237:611-623. [DOI: 10.1007/s00221-018-5442-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 11/21/2018] [Indexed: 01/28/2023]
|
7
|
Physiological effects of low-magnitude electric fields on brain activity: advances from in vitro, in vivo and in silico models. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2018; 8:38-44. [PMID: 31106284 DOI: 10.1016/j.cobme.2018.09.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
While electrical stimulation of brain tissue has been thoroughly investigated over the last decades, ongoing questions remain regarding the neurophysiological effects of low-level electric fields (on the order of 1 V/m) on brain activity. Electric fields at such levels are, for example, induced by transcranial direct/alternating current stimulation (tDCS/tACS). Action potentials can be indeed elicited when applied (supra-threshold) electric fields are in the 10-100 V/m range, while lower (subthreshold) electric fields result in more limited and subtler membrane polarization effects. In this review, we address the question of the mechanisms underlying the immediate effects (also referred to as acute, concurrent or short-term) and the lasting effects (also referred to as long-term or aftereffects) of low-level electric fields on brain tissue. We review recent evidence at the in vitro and in vivo (animal and human) level, and also present mechanistic insights gained from in silico models, which are still few but have received increased attention over the recent past years. We highlight the convergent evidence towards potential mechanisms, and also discuss discrepancies between in vitro studies and human tDCS/tACS studies that require further investigation to bridge the gap between the single-cell and large-scale network level. Possible novel avenues of research are discussed.
Collapse
|
8
|
Saito A, Takahashi M, Makino K, Suzuki Y, Jimbo Y, Nakasono S. Response of Cultured Neuronal Network Activity After High-Intensity Power Frequency Magnetic Field Exposure. Front Physiol 2018; 9:189. [PMID: 29662453 PMCID: PMC5890104 DOI: 10.3389/fphys.2018.00189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 02/23/2018] [Indexed: 01/20/2023] Open
Abstract
High-intensity and low frequency (1-100 kHz) time-varying electromagnetic fields stimulate the human body through excitation of the nervous system. In power frequency range (50/60 Hz), a frequency-dependent threshold of the external electric field-induced neuronal modulation in cultured neuronal networks was used as one of the biological indicator in international guidelines; however, the threshold of the magnetic field-induced neuronal modulation has not been elucidated. In this study, we exposed rat brain-derived neuronal networks to a high-intensity power frequency magnetic field (hPF-MF), and evaluated the modulation of synchronized bursting activity using a multi-electrode array (MEA)-based extracellular recording technique. As a result of short-term hPF-MF exposure (50-400 mT root-mean-square (rms), 50 Hz, sinusoidal wave, 6 s), the synchronized bursting activity was increased in the 400 mT-exposed group. On the other hand, no change was observed in the 50-200 mT-exposed groups. In order to clarify the mechanisms of the 400 mT hPF-MF exposure-induced neuronal response, we evaluated it after blocking inhibitory synapses using bicuculline methiodide (BMI); subsequently, increase in bursting activity was observed with BMI application, and the response of 400 mT hPF-MF exposure disappeared. Therefore, it was suggested that the response of hPF-MF exposure was involved in the inhibitory input. Next, we screened the inhibitory pacemaker-like neuronal activity which showed autonomous 4-10 Hz firing with CNQX and D-AP5 application, and it was confirmed that the activity was reduced after 400 mT hPF-MF exposure. Comparison of these experimental results with estimated values of the induced electric field (E-field) in the culture medium revealed that the change in synchronized bursting activity occurred over 0.3 V/m, which was equivalent to the findings of a previous study that used the external electric fields. In addition, the results suggested that the potentiation of neuronal activity after 400 mT hPF-MF exposure was related to the depression of autonomous activity of pacemaker-like neurons. Our results indicated that the synchronized bursting activity was increased by hPF-MF exposure (E-field: >0.3 V/m), and the response was due to reduced inhibitory pacemaker-like neuronal activity.
Collapse
Affiliation(s)
- Atsushi Saito
- Biological Environment Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Chiba, Japan
| | - Masayuki Takahashi
- Biological Environment Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Chiba, Japan
| | - Kei Makino
- Department of Electrical and Electronic Engineering, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, Japan
| | - Yukihisa Suzuki
- Department of Electrical and Electronic Engineering, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, Japan
| | - Yasuhiko Jimbo
- Department of Precision Engineering, Graduate School of Engineering, University of Tokyo, Tokyo, Japan
| | - Satoshi Nakasono
- Biological Environment Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Chiba, Japan
| |
Collapse
|
9
|
Magne I, Deschamps F. Electric field induced in the human body by uniform 50 Hz electric or magnetic fields: bibliography analysis and method for conservatively deriving measurable limits. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:419-436. [PMID: 27340133 DOI: 10.1088/0952-4746/36/3/419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Health guidelines for electric and magnetic fields in the low frequency range define exposure limits for electric and magnetic fields in terms of induced electric field in the human body, which is not directly measurable, requiring use of dosimetry. However many parameters, such as human models, calculation codes and post-processing methods influence the calculation results. Based upon many published papers and therefore covering a wide range of these influence parameters, this paper proposes a method for conservatively deriving measurable levels of electric and magnetic fields equivalent to the basic restrictions. Following this method, we found that, regarding exposure to uniform fields, the ICNIRP 2010 occupational basic restrictions are equivalent to a 2 mT and 7 mT magnetic field and to a 35 kV m-1 and 35 kV m-1 electric field at 50 Hz when applied respectively to the central and peripheral nervous system.
Collapse
Affiliation(s)
- Isabelle Magne
- Electrical Equipement Laboratory, EDF R&D, Moret sur Loing, France
| | | |
Collapse
|
10
|
Tarao H, Miyamoto H, Korpinen L, Hayashi N, Isaka K. Simple estimation of induced electric fields in nervous system tissues for human exposure to non-uniform electric fields at power frequency. Phys Med Biol 2016; 61:4438-51. [PMID: 27222929 DOI: 10.1088/0031-9155/61/12/4438] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Most results regarding induced current in the human body related to electric field dosimetry have been calculated under uniform field conditions. We have found in previous work that a contact current is a more suitable way to evaluate induced electric fields, even in the case of exposure to non-uniform fields. If the relationship between induced currents and external non-uniform fields can be understood, induced electric fields in nervous system tissues may be able to be estimated from measurements of ambient non-uniform fields. In the present paper, we numerically calculated the induced electric fields and currents in a human model by considering non-uniform fields based on distortion by a cubic conductor under an unperturbed electric field of 1 kV m(-1) at 60 Hz. We investigated the relationship between a non-uniform external electric field with no human present and the induced current through the neck, and the relationship between the current through the neck and the induced electric fields in nervous system tissues such as the brain, heart, and spinal cord. The results showed that the current through the neck can be formulated by means of an external electric field at the central position of the human head, and the distance between the conductor and the human model. As expected, there is a strong correlation between the current through the neck and the induced electric fields in the nervous system tissues. The combination of these relationships indicates that induced electric fields in these tissues can be estimated solely by measurements of the external field at a point and the distance from the conductor.
Collapse
Affiliation(s)
- Hiroo Tarao
- National Institute of Technology, Kagawa College, 355 Chokushi-cho, Takamatsu, Kagawa 761-8058, Japan
| | | | | | | | | |
Collapse
|
11
|
Chan KH, Ohta S, Laakso I, Hirata A, Suzuki Y, Kavet R. Computational dosimetry for child and adult human models due to contact current from 10 Hz to 110 MHz. RADIATION PROTECTION DOSIMETRY 2015; 167:642-652. [PMID: 25344888 DOI: 10.1093/rpd/ncu322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/26/2014] [Indexed: 06/04/2023]
Abstract
This study computationally investigates in situ electric field due to low-frequency contact current and specific absorption rate (SAR) due to high-frequency contact currents in a realistic child model and compared with those in the adult model. The in situ electric fields and SAR in the child model are found to exceed the corresponding values in the adult. At the finger tip, the electric field and SAR due to contact currents, both at the ICNIRP reference levels and IEEE Maximum Permissible Exposures, are well beyond the corresponding basic restrictions. In the remaining part, the largest difference was observed in spinal tissue, and the smallest effect was in the heart. With respect to brain and skin conductivities, one needs to strongly consider which values of tissue properties are used to interpret one's results. The in situ electric fields resulting from contact with the metal plane are similar to those for contact with the wire.
Collapse
Affiliation(s)
- Kwok Hung Chan
- Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-shi 466-8555, Japan City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China
| | - Shunya Ohta
- Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-shi 466-8555, Japan
| | - Ilkka Laakso
- Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-shi 466-8555, Japan
| | - Akimasa Hirata
- Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya-shi 466-8555, Japan
| | | | - Robert Kavet
- Electric Power Research Institute, Palo Alto, CA, USA
| |
Collapse
|
12
|
Zradziński P. Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2015; 21:213-20. [PMID: 26323781 PMCID: PMC4566884 DOI: 10.1080/10803548.2015.1028233] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers' exposure to the electromagnetic field have been considered: workers' body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards.
Collapse
Affiliation(s)
- Patryk Zradziński
- a Central Institute for Labour Protection - National Research Institute (CIOP-PIB) , Poland
| |
Collapse
|
13
|
Gao Y, Yang H. A High-Order, Symplectic, Finite-Difference Time-Domain Scheme for Bioelectromagnetic Applications within the Mother/Fetus Model. PLoS One 2014; 9:e114425. [PMID: 25493433 PMCID: PMC4262409 DOI: 10.1371/journal.pone.0114425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 11/10/2014] [Indexed: 11/18/2022] Open
Abstract
An explicit high-order, symplectic, finite-difference time-domain (SFDTD) scheme is applied to a bioelectromagnetic simulation using a simple model of a pregnant woman and her fetus. Compared to the traditional FDTD scheme, this scheme maintains the inherent nature of the Hamilton system and ensures energy conservation numerically and a high precision. The SFDTD scheme is used to predict the specific absorption rate (SAR) for a simple model of a pregnant female woman (month 9) using radio frequency (RF) fields from 1.5 T and 3 T MRI systems (operating at approximately 64 and 128 MHz, respectively). The results suggest that by using a plasma protective layer under the 1.5 T MRI system, the SAR values for the pregnant woman and her fetus are significantly reduced. Additionally, for a 90 degree plasma protective layer, the SAR values are approximately equal to the 120 degree layer and the 180 degree layer, and it is reduced relative to the 60 degree layer. This proves that using a 90 degree plasma protective layer is the most effective and economical angle to use.
Collapse
Affiliation(s)
- YingJie Gao
- Department of Physics, College of Science, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - HongWei Yang
- Department of Physics, College of Science, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
- * E-mail:
| |
Collapse
|
14
|
Shimamoto T, Laakso I, Hirata A. In-situ electric field in human body model in different postures for wireless power transfer system in an electrical vehicle. Phys Med Biol 2014; 60:163-73. [PMID: 25479377 DOI: 10.1088/0031-9155/60/1/163] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The in-situ electric field of an adult male model in different postures is evaluated for exposure to the magnetic field leaked from a wireless power transfer system in an electrical vehicle. The transfer system is located below the centre of the vehicle body and the transferred power and frequency are 7 kW and 85 kHz, respectively. The in-situ electric field is evaluated for a human model (i) crouching near the vehicle, (ii) lying on the ground with or without his arm stretched, (iii) sitting in the driver's seat, and (iv) standing on a transmitting coil without a receiving coil. In each scenario, the maximum in-situ electric fields are lower than the allowable limit prescribed by international guidelines, although the local magnetic field strength in regions of the human body is higher than the allowable external magnetic field strength. The highest in-situ electric field is observed when the human body model is placed on the ground with his arm extended toward the coils, because of a higher magnetic field around the arm.
Collapse
Affiliation(s)
- Takuya Shimamoto
- Nagoya Institute of Technology Department of Computer Science and Engineering, Nagoya 466-8555, Japan
| | | | | |
Collapse
|
15
|
Laakso I, Hirata A. Evaluation of the induced electric field and compliance procedure for a wireless power transfer system in an electrical vehicle. Phys Med Biol 2013; 58:7583-93. [PMID: 24107570 DOI: 10.1088/0031-9155/58/21/7583] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, an induced electric field in a human body is evaluated for the magnetic field leaked from a wireless power transfer system for charging an electrical vehicle. The magnetic field from the wireless power transfer system is modelled computationally, and its effectiveness is confirmed by comparison with the field measured in a previous study. The induced electric field in a human standing around the vehicle is smaller than the allowable limit prescribed in international guidelines, although the magnetic field strength in the human body is locally higher than the allowable external field strength. Correlation between the external magnetic field and the induced electric field is confirmed to be reasonable at least in the standing posture, which is the case discussed in the international standard. Based on this finding, we discussed and confirmed the applicability of a three-point magnetic field measurement at heights of 0.5, 1.0, and 1.5 m for safety compliance.
Collapse
Affiliation(s)
- Ilkka Laakso
- Department of Computer Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | | |
Collapse
|
16
|
Chen XL, Benkler S, Chavannes N, De Santis V, Bakker J, van Rhoon G, Mosig J, Kuster N. Analysis of human brain exposure to low-frequency magnetic fields: a numerical assessment of spatially averaged electric fields and exposure limits. Bioelectromagnetics 2013; 34:375-84. [PMID: 23404214 DOI: 10.1002/bem.21780] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 12/30/2012] [Indexed: 11/10/2022]
Abstract
Compliance with the established exposure limits for the electric field (E-field) induced in the human brain due to low-frequency magnetic field (B-field) induction is demonstrated by numerical dosimetry. The objective of this study is to investigate the dependency of dosimetric compliance assessments on the applied methodology and segmentations. The dependency of the discretization uncertainty (i.e., staircasing and field singularity) on the spatially averaged peak E-field values is first determined using canonical and anatomical models. Because spatial averaging with a grid size of 0.5 mm or smaller sufficiently reduces the impact of artifacts regardless of tissue size, it is a superior approach to other proposed methods such as the 99th percentile or smearing of conductivity contrast. Through a canonical model, it is demonstrated that under the same uniform B-field exposure condition, the peak spatially averaged E-fields in a heterogeneous model can be significantly underestimated by a homogeneous model. The frequency scaling technique is found to introduce substantial error if the relative change in tissue conductivity is significant in the investigated frequency range. Lastly, the peak induced E-fields in the brain tissues of five high-resolution anatomically realistic models exposed to a uniform B-field at ICNIRP and IEEE reference levels in the frequency range of 10 Hz to 100 kHz show that the reference levels are not always compliant with the basic restrictions. Based on the results of this study, a revision is recommended for the guidelines/standards to achieve technically sound exposure limits that can be applied without ambiguity.
Collapse
Affiliation(s)
- Xi-Lin Chen
- Foundation for Research on Information Technologies in Society-IT'IS, Zurich, Switzerland.
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Kavet R, Dovan T, Reilly JP. The relationship between anatomically correct electric and magnetic field dosimetry and publishe delectric and magnetic field exposure limits. RADIATION PROTECTION DOSIMETRY 2012; 152:279-295. [PMID: 22619351 DOI: 10.1093/rpd/ncs064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Electric and magnetic field exposure limits published by International Commission for Non-Ionizing Radiation Protection and Institute of Electrical and Electronics Engineers are aimed at protection against adverse electrostimulation, which may occur by direct coupling to excitable tissue and, in the case of electric fields, through indirect means associated with surface charge effects (e.g. hair vibration, skin sensations), spark discharge and contact current. For direct coupling, the basic restriction (BR) specifies the not-to-be-exceeded induced electric field. The key results of anatomically based electric and magnetic field dosimetry studies and the relevant characteristics of excitable tissue were first identified. This permitted us to assess the electric and magnetic field exposure levels that induce dose in tissue equal to the basic restrictions, and the relationships of those exposure levels to the limits now in effect. We identify scenarios in which direct coupling of electric fields to peripheral nerve could be a determining factor for electric field limits.
Collapse
Affiliation(s)
- Robert Kavet
- Electric Power Research Institute, 3420 Hillview Avenue, Palo Alto, CA 94304, USA.
| | | | | |
Collapse
|
18
|
|
19
|
Kos B, Valič B, Kotnik T, Gajšek P. Occupational exposure assessment of magnetic fields generated by induction heating equipment—the role of spatial averaging. Phys Med Biol 2012; 57:5943-53. [DOI: 10.1088/0031-9155/57/19/5943] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
20
|
Laakso I, Hirata A. Reducing the staircasing error in computational dosimetry of low-frequency electromagnetic fields. Phys Med Biol 2012; 57:N25-34. [DOI: 10.1088/0031-9155/57/4/n25] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|