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Volume 24, Issue 4 (Winter 2023)
Advances in Cognitive Sciences 2023, 24(4): 132-145 |
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Feizipour Namaghi M, Mahdavi S M, Karami M, Nasiri Khalili M A, Vahedi V, Modarresi Chahardehi A. The effect of S-band microwave radiation on brain hippocampal tissue using COMSOL multiphysics. Advances in Cognitive Sciences 2023; 24 (4) :132-145
URL: http://icssjournal.ir/article-1-1471-en.html
URL: http://icssjournal.ir/article-1-1471-en.html
Mahmoud Feizipour Namaghi1 
, Seyed Mohammad Mahdavi * 2, Mohammad Karami3 , Mohammad Ali Nasiri Khalili2 , Vahid Vahedi4 , Amir Modarresi Chahardehi5
, Seyed Mohammad Mahdavi * 2, Mohammad Karami3 , Mohammad Ali Nasiri Khalili2 , Vahid Vahedi4 , Amir Modarresi Chahardehi5
1- Department of Bioscience and Biotechnology, Malek-Ashtar University of Technology (MUT), Tehran, Iran
2- Assistant Professor, Department of Bioscience and Biotechnology, Malek Ashtar University of Technology (MUT), Tehran, Iran
3- Department of Electrical Engineering, Malek-Ashtar University of Technology (MUT), Tehran, Iran
4- MA, Department of Physics, Imam Khomeini International University, Qazvin, Iran
5- Cognitive Neuroscience Research Center, AJA University of Medical Science, Tehran, Iran
2- Assistant Professor, Department of Bioscience and Biotechnology, Malek Ashtar University of Technology (MUT), Tehran, Iran
3- Department of Electrical Engineering, Malek-Ashtar University of Technology (MUT), Tehran, Iran
4- MA, Department of Physics, Imam Khomeini International University, Qazvin, Iran
5- Cognitive Neuroscience Research Center, AJA University of Medical Science, Tehran, Iran
Abstract: (801 Views)
Introduction
Electromagnetic fields (EMFs) are emitted by many biological and manufactured sources and are vital in daily living. EMFs are a daily threat to over three billion people globally. The IEEE defines the microwave band, which includes the S-band, as part of the electromagnetic spectrum and a radar-frequency band. The S-band operates in the 2-4 GHz range and is used chiefly for radar and communication. Due to the limitations of studying the effects of EMFs on humans and animals, simulating the impacts of waves on biological tissue using a computer has many advantages because the S-band is released for a brief time adjacent to the human head during communication.
The CNS is one of the most sensitive human organ systems and is particularly vulnerable to microwave radiation. Studies on the impact of EMF on the CNS and cognition are needed. EMF radiation can be absorbed by organisms, resulting in physiological and functional changes and raising concern about potential health implications. The brain is one of the most vulnerable organs to microwave radiation. Psenakova et al. showed that the interaction of the human head with electromagnetic radiation from cell phones might cause harmful electric currents and fields inside the brain (14). Nevertheless, temperature variations are responsible for virtually all documented behavioral repercussions as Mobashsher et al. mentioned that when a signal reaches the head, it interacts with an irregularly thin layer of high permittivity skin (50-44 over the range 0.75-2.55 GHz) and then penetrates through thick fat and low permittivity skull layers (16). Following that, the signal passes through extremely high permittivity cerebrospinal fluid (CSF) (69-66.2 over the range 0.75-2.55 GHz) and Dura (44-41.9 across the band 0.75-2.55 GHz) tissues and finally through grey and white matter.
The hippocampus is a complex brain structure in the temporal lobe that plays a critical role in memory and learning. As previously discussed, memory is a vital cognitive function. The hippocampal tissue is frequently assumed to be the site of long-term memory and is required to function correctly. Damage to the hippocampus, the limbic system’s cornerstone, results in impairments in converting short- to long-term memory, a uniquely cognitive function. Therefore, the present study simulates and investigates the effects of S-band electromagnetic waves on hippocampus tissue. COMSOL Multiphysics presents a simplified method for this more accurate and informative stimulation than earlier.
Methods
Radiation system
The effect of distant field electromagnetics on brain layers simulated in different power output modes was investigated. The waves are radiated from three angles: posterior (behind), anterior (in front), and lateral of the head. The temperature rise in the skull layers and hippocampus and the amount of SAR (Specific absorption rate) have been recorded. In free space, the waves are emitted as plane waves. COMSOL Multiphysics version 5.4a solves the bioheat and bioelectromagnetic wave equations in the frequency domain and time-dependent heat transformation problems. This experiment simulates radar’s electromagnetic fields. Magnetic fields are mostly ineffectual between the radiation source and the biological tissue, but electric fields are effective once they reach the biological tissue. These findings may be applied to any radar system that operates at 2.45 GHz, has a radiation source at a distance of over ten meters (remote field), an antenna gain of 30 dB, and a radiation output source ranging from 0 watts to about 20263 watts. The duration of radiation was thirty minutes. Therefore, the results may be applicable if any radars used in military, meteorological, or other applications meet these criteria.
This study applied the sphere’s geometry with the radius and thickness provided to represent the layers of the human head. Two models of four or seven layers are frequently used to simulate the human skull. COMSOL Multiphysics version 5.4a created a seven-layer model of skin, fat, muscle, skull, dura, cerebrospinal fluid (CSF), and brain tissue. The human hippocampus is frequently estimated to measure between 3 and 4 cm3. In this study, the hippocampus is assumed to be 3 cm3. Using the simplified Friis equation to calculate the electric field power in distant fields, the authors first determined the wave power received from a source close to the biological tissue.
Results
This study investigated the effect of 2.45 GHz electromagnetic waves on various electric field strengths. The heat maps of head layers illustrate how electromagnetic waves affect the hippocampus and cognitive memory function. A temperature increase in the skull’s layers and hippocampus tissue occurs by radiating S-band microwave electromagnetic waves generated by distant fields from three directions: the head’s posterior, anterior, and lateral sides. However, this increase is negligible, and its temperature tolerance ranges from 0.0001°C (the lowest temperature increase associated with the state of radiation in front of a 20 V/m electric field) to 0.016°C (the highest temperature increase associated with the radiated from behind the head in a 120 V/m electric field). The SAR in hippocampus tissue rose by increasing electric field intensity and tissue temperature. The energy absorption tolerance varies from 0.18×10-3 W/kg (the lowest increase in temperature corresponds to the electric field of 20 V/m) to 22×10-2 W/kg (the maximum increase in exposure to temperature emitted from the back of the head in an electric field of 120 V/m). The rate of temperature rises and SAR variations in the hippocampus tissue when the intensity is 20 V/m (selected from various intensities). The radiation source is positioned in front, behind, and lateral.
When the radiation is applied to the lateral side of the head, an electric field strength of 20 to 120 V/m results in a temperature rise of between 0.0003°C to 0.012°C. In addition, the authors observed an increase in SAR from 0.45×10-2 to 16×10-2 W/kg. One-way ANOVA using Tukey’s post hoc test revealed no significant difference in temperature fluctuations across the front, behind, and lateral hippocampal tissue (P=0.1225). However, the authors found a significant difference (P<0.0001) between various SAR (20-120 V/m) in different positions (front, behind, and lateral) (data are not shown).
While the electric field is being radiated to the front of the head, raising the intensity from 20 to 120 V/m leads to a temperature increase of 0.0001°C to 0.0035°C and an increase in SAR from 0.18×10-3 to 60×10-3 W/kg. When electromagnetic waves are emitted from behind the head, electric field radiation intensity ranging from 20 to 120 V/m causes a temperature rise of 0.004°C to 0.016°C and a SAR increase of 0.6×10-2 to 22×10-2 W/kg.
Conclusion
This study aims to construct a realistic and complete model of head layers using the COMSOL Multiphysics software. Biophysical wave interventions may cause non-thermal effects in the brain’s hippocampal tissue due to small changes in its temperature tolerance caused by exposure to S-band microwave electromagnetic waves in the present study. Non-thermal effects in the brain can be induced through the non-thermal interaction of external electromagnetic waves with brain waves or through the phase difference and attenuation of brain waves caused by external electric fields. Therefore, this study verifies the non-thermal impact mechanisms of electromagnetic waves described in previous studies on their influence on the hippocampus. However, these non-thermal interventions are negligible and safe. Therefore, this study confirms the non-thermal effect mechanisms of electromagnetic waves presented in previous studies about their effect on the hippocampus. This study states that the electromagnetic waves with the specified radiation protocol, in terms of thermal effects, probably do not have any particular outcome in this experiment. According to the studies in this field, it is suggested that the damage to the hippocampus and the cognitive processes results from the non-thermal effects of electromagnetic waves with a frequency of 2.45 GHz and the radiation intensity and duration mentioned.
Ethical Consideration
Compliance with ethical guidelines
This study was based on a software program instead of an animal/human study.
Authors’ contributions
Seyed Mohammad Mahdavi and Mohammad Ali Nasiri Khalili designed the study; Mahmoud Feizipour Namaghi collected and interpreted the data; Mahmoud Feizipour Namaghi and Mohammad Karami checked the data; Vahid Vahedi and Amir Modarresi Chahardehi analyzed the data; and Amir Modarresi Chahardehi and Mahmoud Feizipour Namaghi wrote and edited the manuscript. This research was conducted under the supervision of Seyed Mohammad Mahdavi.
Funding
The authors did not receive funding for this study.
Acknowledgments
The authors are grateful to all the people who cooperated in this research.
Conflict of interest
The authors declare no conflicts of interest.
Electromagnetic fields (EMFs) are emitted by many biological and manufactured sources and are vital in daily living. EMFs are a daily threat to over three billion people globally. The IEEE defines the microwave band, which includes the S-band, as part of the electromagnetic spectrum and a radar-frequency band. The S-band operates in the 2-4 GHz range and is used chiefly for radar and communication. Due to the limitations of studying the effects of EMFs on humans and animals, simulating the impacts of waves on biological tissue using a computer has many advantages because the S-band is released for a brief time adjacent to the human head during communication.
The CNS is one of the most sensitive human organ systems and is particularly vulnerable to microwave radiation. Studies on the impact of EMF on the CNS and cognition are needed. EMF radiation can be absorbed by organisms, resulting in physiological and functional changes and raising concern about potential health implications. The brain is one of the most vulnerable organs to microwave radiation. Psenakova et al. showed that the interaction of the human head with electromagnetic radiation from cell phones might cause harmful electric currents and fields inside the brain (14). Nevertheless, temperature variations are responsible for virtually all documented behavioral repercussions as Mobashsher et al. mentioned that when a signal reaches the head, it interacts with an irregularly thin layer of high permittivity skin (50-44 over the range 0.75-2.55 GHz) and then penetrates through thick fat and low permittivity skull layers (16). Following that, the signal passes through extremely high permittivity cerebrospinal fluid (CSF) (69-66.2 over the range 0.75-2.55 GHz) and Dura (44-41.9 across the band 0.75-2.55 GHz) tissues and finally through grey and white matter.
The hippocampus is a complex brain structure in the temporal lobe that plays a critical role in memory and learning. As previously discussed, memory is a vital cognitive function. The hippocampal tissue is frequently assumed to be the site of long-term memory and is required to function correctly. Damage to the hippocampus, the limbic system’s cornerstone, results in impairments in converting short- to long-term memory, a uniquely cognitive function. Therefore, the present study simulates and investigates the effects of S-band electromagnetic waves on hippocampus tissue. COMSOL Multiphysics presents a simplified method for this more accurate and informative stimulation than earlier.
Methods
Radiation system
The effect of distant field electromagnetics on brain layers simulated in different power output modes was investigated. The waves are radiated from three angles: posterior (behind), anterior (in front), and lateral of the head. The temperature rise in the skull layers and hippocampus and the amount of SAR (Specific absorption rate) have been recorded. In free space, the waves are emitted as plane waves. COMSOL Multiphysics version 5.4a solves the bioheat and bioelectromagnetic wave equations in the frequency domain and time-dependent heat transformation problems. This experiment simulates radar’s electromagnetic fields. Magnetic fields are mostly ineffectual between the radiation source and the biological tissue, but electric fields are effective once they reach the biological tissue. These findings may be applied to any radar system that operates at 2.45 GHz, has a radiation source at a distance of over ten meters (remote field), an antenna gain of 30 dB, and a radiation output source ranging from 0 watts to about 20263 watts. The duration of radiation was thirty minutes. Therefore, the results may be applicable if any radars used in military, meteorological, or other applications meet these criteria.
This study applied the sphere’s geometry with the radius and thickness provided to represent the layers of the human head. Two models of four or seven layers are frequently used to simulate the human skull. COMSOL Multiphysics version 5.4a created a seven-layer model of skin, fat, muscle, skull, dura, cerebrospinal fluid (CSF), and brain tissue. The human hippocampus is frequently estimated to measure between 3 and 4 cm3. In this study, the hippocampus is assumed to be 3 cm3. Using the simplified Friis equation to calculate the electric field power in distant fields, the authors first determined the wave power received from a source close to the biological tissue.
Results
This study investigated the effect of 2.45 GHz electromagnetic waves on various electric field strengths. The heat maps of head layers illustrate how electromagnetic waves affect the hippocampus and cognitive memory function. A temperature increase in the skull’s layers and hippocampus tissue occurs by radiating S-band microwave electromagnetic waves generated by distant fields from three directions: the head’s posterior, anterior, and lateral sides. However, this increase is negligible, and its temperature tolerance ranges from 0.0001°C (the lowest temperature increase associated with the state of radiation in front of a 20 V/m electric field) to 0.016°C (the highest temperature increase associated with the radiated from behind the head in a 120 V/m electric field). The SAR in hippocampus tissue rose by increasing electric field intensity and tissue temperature. The energy absorption tolerance varies from 0.18×10-3 W/kg (the lowest increase in temperature corresponds to the electric field of 20 V/m) to 22×10-2 W/kg (the maximum increase in exposure to temperature emitted from the back of the head in an electric field of 120 V/m). The rate of temperature rises and SAR variations in the hippocampus tissue when the intensity is 20 V/m (selected from various intensities). The radiation source is positioned in front, behind, and lateral.
When the radiation is applied to the lateral side of the head, an electric field strength of 20 to 120 V/m results in a temperature rise of between 0.0003°C to 0.012°C. In addition, the authors observed an increase in SAR from 0.45×10-2 to 16×10-2 W/kg. One-way ANOVA using Tukey’s post hoc test revealed no significant difference in temperature fluctuations across the front, behind, and lateral hippocampal tissue (P=0.1225). However, the authors found a significant difference (P<0.0001) between various SAR (20-120 V/m) in different positions (front, behind, and lateral) (data are not shown).
While the electric field is being radiated to the front of the head, raising the intensity from 20 to 120 V/m leads to a temperature increase of 0.0001°C to 0.0035°C and an increase in SAR from 0.18×10-3 to 60×10-3 W/kg. When electromagnetic waves are emitted from behind the head, electric field radiation intensity ranging from 20 to 120 V/m causes a temperature rise of 0.004°C to 0.016°C and a SAR increase of 0.6×10-2 to 22×10-2 W/kg.
Conclusion
This study aims to construct a realistic and complete model of head layers using the COMSOL Multiphysics software. Biophysical wave interventions may cause non-thermal effects in the brain’s hippocampal tissue due to small changes in its temperature tolerance caused by exposure to S-band microwave electromagnetic waves in the present study. Non-thermal effects in the brain can be induced through the non-thermal interaction of external electromagnetic waves with brain waves or through the phase difference and attenuation of brain waves caused by external electric fields. Therefore, this study verifies the non-thermal impact mechanisms of electromagnetic waves described in previous studies on their influence on the hippocampus. However, these non-thermal interventions are negligible and safe. Therefore, this study confirms the non-thermal effect mechanisms of electromagnetic waves presented in previous studies about their effect on the hippocampus. This study states that the electromagnetic waves with the specified radiation protocol, in terms of thermal effects, probably do not have any particular outcome in this experiment. According to the studies in this field, it is suggested that the damage to the hippocampus and the cognitive processes results from the non-thermal effects of electromagnetic waves with a frequency of 2.45 GHz and the radiation intensity and duration mentioned.
Ethical Consideration
Compliance with ethical guidelines
This study was based on a software program instead of an animal/human study.
Authors’ contributions
Seyed Mohammad Mahdavi and Mohammad Ali Nasiri Khalili designed the study; Mahmoud Feizipour Namaghi collected and interpreted the data; Mahmoud Feizipour Namaghi and Mohammad Karami checked the data; Vahid Vahedi and Amir Modarresi Chahardehi analyzed the data; and Amir Modarresi Chahardehi and Mahmoud Feizipour Namaghi wrote and edited the manuscript. This research was conducted under the supervision of Seyed Mohammad Mahdavi.
Funding
The authors did not receive funding for this study.
Acknowledgments
The authors are grateful to all the people who cooperated in this research.
Conflict of interest
The authors declare no conflicts of interest.
Type of Study: Research |
Received: 2022/10/7 | Accepted: 2023/01/2 | Published: 2023/02/19
Received: 2022/10/7 | Accepted: 2023/01/2 | Published: 2023/02/19
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