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Chen X.L.,Ecole Polytechnique Federale de Lausanne | Umenei A.E.,The Innovation Group | Baarman D.W.,The Innovation Group | Chavannes N.,Foundation for Research on Information Technologies in Society itIs Foundation | And 4 more authors.
IEEE Transactions on Electromagnetic Compatibility | Year: 2014

In this study, human exposure to close-range wireless power transfer (WPT) systems operating in the frequency range 0.1-10 MHz with coil diameters up to 150 mm are investigated. Approximation formulae, which include scaling factors derived from numerical simulations that take variations of complex human anatomies into consideration, are proposed to conservatively estimate human exposure with respect to the most authoritative exposure guidelines. The approximation has been verified for two precommercial prototype WPT systems, the first of which, a 5-W system operating at 100 kHz, has been evaluated in this study; the second system been verified was reported in a separate study and operates at 6.78 MHz with a nominal current of 5.4 A\rm \bf rms. Based on the results obtained, the optimal operational frequency range for WPT with respect to compliance with exposure safety guidelines is revealed to be ca. 1-2.5 MHz. In summary, this study provides novel and insightful information for the design of an exposure-compliant close-range magnetic resonant WPT system. © 2014 IEEE. Source


Christ A.,Foundation for Research on Information Technologies in Society itIs Foundation | Douglas M.,Foundation for Research on Information Technologies in Society itIs Foundation | Nadakuduti J.,Foundation for Research on Information Technologies in Society itIs Foundation | Nadakuduti J.,Qualcomm | And 2 more authors.
Proceedings of the IEEE | Year: 2013

The strong reactive near-field wireless power transmission (WPT) systems induce electric fields in the body tissue of persons in their close vicinity. This may pose potential direct health hazards or indirect risks via interference with medical implants. In this paper, the safety guidelines and the fundamental coupling mechanisms of the human body with the electromagnetic near fields of WPT are reviewed as well as the methodology and the instrumentation for the demonstration of the safety of such systems operating between 100 kHz and 50 MHz. Based on this review, the advantages and shortcomings of state-of-the-art numerical and experimental techniques are discussed and applied to a generic WPT operating at 8 MHz. Finally, current research needs are identified which include: 1) the extension of safety guidelines for coverage of persons with implants; 2) more computationally efficient full-wave solvers; 3) higher quality human models which cover different population groups and include improved models of nerve tissue; 4) experimental dosimetric methods for the WPT frequency range; and 5) product standards to demonstrate safety of specific WPT. © 1963-2012 IEEE. Source


Douglas M.G.,Foundation for Research on Information Technologies in Society itIs Foundation | Portelli L.,Foundation for Research on Information Technologies in Society itIs Foundation | Carrasco E.,Foundation for Research on Information Technologies in Society itIs Foundation | Christ A.,Foundation for Research on Information Technologies in Society itIs Foundation | And 3 more authors.
2016 10th European Conference on Antennas and Propagation, EuCAP 2016 | Year: 2016

Novel measurement technologies for specific absorption rate (SAR) assessment of wireless devices have been developed using sensor arrays to dramatically reduce the measurement time compared to single-probe scanning systems. While single-probe scanning systems are optimized for low measurement uncertainty and source-independent accuracy, array systems are in widespread use for design testing and have made significant advances in accuracy. This has encouraged regulatory agencies and standards organization to develop procedures for their use in compliance testing of wireless devices. Central to the acceptance of array systems are comprehensive procedures for the validation of the measurement accuracy and determination of the measurement uncertainty. In this paper, a validation protocol is proposed. The protocol is applied using a popular sensor array system. The results are used to demonstrate the conservativeness of the uncertainty budget. © 2016 European Association of Antennas and Propagation. Source


Barretto E.C.S.,Zurich Med Tech | Chavannes N.,Zurich Med Tech | Chavannes N.,Foundation for Research on Information Technologies in Society itIs Foundation | Douglas M.,Foundation for Research on Information Technologies in Society itIs Foundation
2016 10th European Conference on Antennas and Propagation, EuCAP 2016 | Year: 2016

The combination of the latest advances in numerical simulation platforms with the development of highly detailed computable human phantoms has led to very realistic results, turning them into powerful tools on the assessment of safety and compliance in the context of wireless power transfer applications. This work makes a deeper investigation of important simulation-related aspects typical of this technology, by means of computing and validating three different application scenarios of wireless charging using finite-difference time-domain method and measurements. The results aim to serve as aid on choosing the most appropriate parameters and platform as to lead to the most time-saving and reliable simulation results for compliance submission. © 2016 European Association of Antennas and Propagation. Source


Nadakuduti J.,Foundation for Research on Information Technologies in Society itIs Foundation | Nadakuduti J.,ETH Zurich | Douglas M.,Foundation for Research on Information Technologies in Society itIs Foundation | Capstick M.,Foundation for Research on Information Technologies in Society itIs Foundation | And 3 more authors.
Bioelectromagnetics | Year: 2012

The development of scientifically sound instrumentation, methods, and procedures for the electromagnetic exposure assessment of compact fluorescent lamps (CFLs) is investigated. The incident and induced fields from 11 CFLs have been measured in the 10kHz-1MHz range, and they are compared with the levels for incandescent and light emitting diode (LED) bulbs. Commercially available equipment was used to measure the incident fields, while a novel sensor was built to assess the induced fields in humans. Incident electric field levels significantly exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels at close distances for some sources, while the induced fields are within the ICNIRP basic restrictions. This demonstrates the importance of assessing the induced fields rather than the incident fields for these sources. Maximum current densities for CFLs are comparable to the limits (in the range of 9% to 56%), demonstrating the need for measurements to establish compliance. For the frequency range investigated, the induced fields were found to be considerably higher for CFLs than for incandescent light bulbs, while the exposure from the two LED bulbs was low. The proposed instrumentation and methods offer several advantages over an existing measurement standard, and the measurement uncertainty is significantly better than the assessment of electric and magnetic fields at close distances. © 2011 Wiley Periodicals, Inc. Source

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