Comparison of numerical and experimental methods for determination of SAR and radiation patterns of handheld wireless telephones

Gandhi, O.P.; Lazzi, Gianluca; Tinniswood, A.D.; Yu, Qi Shan

doi:10.1002/(sici)1521-186x(1999)20:4+<93::aid-bem11>3.0.co;2-8

Cited by 28 publications

(5 citation statements)

References 13 publications

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“…The timing of epidemiologic studies and the lack of knowledge about actual RF exposure to the brain from mobile phone use to date (Ghandi et al 1999) militate strongly against current ability to detect any true association. Thus current evidence is inconclusive regarding cancer risk after heavy RF exposure from mobile phones.…”

Section: Review Of Studies On Mobile Phone Usementioning

confidence: 99%

Epidemiology of Health Effects of Radiofrequency Exposure

Ahlbom

Green

Kheifets

et al. 2004

Environ Health Perspect

259

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We have undertaken a comprehensive review of epidemiologic studies about the effects of radiofrequency fields (RFs) on human health in order to summarize the current state of knowledge, explain the methodologic issues that are involved, and aid in the planning of future studies. There have been a large number of occupational studies over several decades, particularly on cancer, cardiovascular disease, adverse reproductive outcome, and cataract, in relation to RF exposure. More recently, there have been studies of residential exposure, mainly from radio and television transmitters, and especially focusing on leukemia. There have also been studies of mobile telephone users, particularly on brain tumors and less often on other cancers and on symptoms. Results of these studies to date give no consistent or convincing evidence of a causal relation between RF exposure and any adverse health effect. On the other hand, the studies have too many deficiencies to rule out an association. A key concern across all studies is the quality of assessment of RF exposure. Despite the ubiquity of new technologies using RFs, little is known about population exposure from RF sources and even less about the relative importance of different sources. Other cautions are that mobile phone studies to date have been able to address only relatively short lag periods, that almost no data are available on the consequences of childhood exposure, and that published data largely concentrate on a small number of outcomes, especially brain tumor and leukemia.

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Section: Review Of Studies On Mobile Phone Usementioning

confidence: 99%

Epidemiology of Health Effects of Radiofrequency Exposure

Ahlbom

Green

Kheifets

et al. 2004

Environ Health Perspect

259

View full text Add to dashboard Cite

show abstract

“…6,7,10,12,[17][18][19][20]23,27,33,35,39 In addition, studies have been conducted on the effects of implantable chips placed on the retina, cardiac muscle, and other structures within the body. 4,8,15,16,26,30,34,37 However, much less has been done on the consequences of wirelessly powering devices within the skull 14,31 .…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

2007

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To fully understand neural function, chronic neural recordings must be made simultaneously from 10s or 100s of neurons. To accomplish this goal, several groups are developing brain machine interfaces. For these devices to be viable for chronic human use, it is likely that they will need to be operated and powered externally via a radiofrequency (RF) source. However, RF exposure can result in tissue heating and is regulated by the FDA/FCC. This paper provides an initial estimate of the amount of tissue heating and specific absorption rate (SAR) associated with the operation of a brain-machine interface (BMI). The operation of a brain machine interface was evaluated in an 18-tissue anatomically detailed human head mesh using simulations of electromagnetics and bio-heat phenomena. The simulations were conducted with a single chip, as well as with eight chips, placed on the surface of the human brain and each powered at four frequencies (13.6 MHz, 1.0 GHz, 2.4 GHz, and 5.8 GHz). The simulated chips consist of a wire antenna on a silicon chip covered by a Teflon dura patch. SAR values were calculated using the finite-difference time-domain method and used to predict peak temperature changes caused by electromagnetic absorption in the head using two-dimensional bio-heat equation. Results due to SAR alone show increased heating at higher frequencies, with a peak temperature change at 5.8 GHz of approximately 0.018 degrees C in the single-chip configuration and 0.06 degrees C in the eight-chip configuration with 10 mW of power absorption (in the human head) per chip. In addition, temperature elevations due to power dissipation in the chip(s) were studied. Results show that for the neural tissue, maximum temperature rises of 3.34 degrees C in the single-chip configuration and 7.72 degrees C in the eight-chip configuration were observed for 10 mW dissipation in each chip. Finally, the maximum power dissipation allowable in each chip before a 1.0 degrees C temperature increase (most stringent standards as denoted in the FDA guidelines) is exceeded in the head was simulated and found to be 2.92 mW in the single-chip configuration and 1.25 mW in the eight-chip configuration. As thermal heating due to SAR was insignificant, this study suggests that wireless electromagnetics, i.e., RF may be a viable option for powering, and communicating with brain machine interfaces for clinical applications.

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“…The obtained relative permeability value represents the behaviour of brain at approximately 350 MHz, whereas the conductivity value of 0.92 indicates the conductivity value of brain at 850 MHz. Also relative permeability value was found to exceed the acceptable deviation of 5% stated in [41]. Another study on HEL is presented in [40].…”

Section: Composing Head Equivalent Liquids (Hels)mentioning

confidence: 99%

Head Equivalent Liquids: A Review on Composing, Recipes and Standards

Sorgucu¹,

Develı²

2016

World Congress on Electrical Engineering and Computer Systems and Science

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-Most of the electric-powered devices and systems emit electromagnetic energy to their environment. The main risk related to the absorption of this energy by biological bodies is commonly assumed to be the temperature rise. Investigation of temperature rise on human body, likely to occur during exposure to electromagnetic fields, conflicts with the code of ethics in academic research. This has led to the need for production of tissue equivalent liquids. Preparation of tissue equivalent liquids, used for determination of hyperthermia and dosimetry values, as well as the SAR (Specific Absorption Rate) values of the cell phones, requires high precision. The present study summarizes how to achieve a tissue equivalent liquid with references to recent progress in the literature with a view to become a pioneering effort for all researchers working in the field.

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Comparison of numerical and experimental methods for determination of SAR and radiation patterns of handheld wireless telephones

Cited by 28 publications

References 13 publications

Epidemiology of Health Effects of Radiofrequency Exposure

Epidemiology of Health Effects of Radiofrequency Exposure

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

Head Equivalent Liquids: A Review on Composing, Recipes and Standards

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