Exploration of Whole Human Body and UWB Radiation Interaction by Efficient and Accurate Two-Debye-Pole Tissue Models
ABSTRACT We have developed a computationally efficient finite-difference time-domain (FDTD) model of a whole human body based on accurate 2-pole Debye dispersion dielectric tissue properties. Comprehensive FDTD analyses of the interaction between a whole human body and ultrawideband (UWB) radiation are carried out by including the proposed frequency dependent tissue models. The 2-pole Debye models have been obtained for 50 individual human tissues from Gabriel's Cole-Cole data by the least squares fitting technique over the frequency range from 100 MHz to 6 GHz. A whole human body composed of the 2-pole Debye models is exposed to spread spectrum radiation. Local energy absorption in a human body is compared between the proposed model and the conventional model of frequency-independent permittivity and conductivity. Resonance states are then investigated in the human body exposed to electromagnetic nano-second pulse radiation. For the extraction of the frequency contents from the highly damped FDTD time signals, a spectrum analysis technique based on an auto-regressive (AR) model has been applied. Pulse propagation in the vicinity of the human body is also characterized by the proposed model for the wireless body area network (WBAN) application that has been proposed recently for computer assisted medical diagnostics and rehabilitation.
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ABSTRACT: form only given. Systems emitting High Power Microwave Ultra Wide Band (HPM/UWB) pulses are developed for both military and civilian applications. The knowledge of the biological effects of this type of radiation is crucial for the protection of the staffs involved in UWB system development but also within the framework of their future uses. As no exposure standard exists, the French-German Research Institute of Saint-Louis has initiated a research program in this area. This program was constituted firstly by a bibliographical survey on the damage mechanisms, the dosimetry and the biological effects. At the sight of the results, it has been considered necessary to measure HPM/UWB pulse propagation in tissue-mimicking phantom materials as mainly numerical works were done on this topic. Indeed the question of the electromagnetic field amplitude in biological tissues and of the loss of energy along its propagation is crucial for the determination of damage mechanisms that can be expected. In this purpose, D-dot probes were used to measure the electric displacement field and set into materials that possess the dispersive dielectric properties of human soft tissues over the microwave frequency range, from 100 MHz to 3 GHz. Cubes of phantom materials containing D-dot were exposed to HPM/UWB pulses which have the following characteristics: a sub-nanosecond rise time, an electric field amplitude of 350 kV m-1 and a pulse duration of 3 ns. This paper will present the results of the bibliographical survey and of these experiments. Additionally, at our best knowledge, no studies dealing with the impact of HPM/UWB pulses on Active Implementable Medical Devices (AIMDs) were published. Consequently, this aspect has also been examined. Implementable Cardiac Pacemaker (ICP) was selected as AIMD since it is the most frequently implemented and it has to maintain vital functions. A bibliographic study was done to determine the in vitro experimental protocol. This latter was b- sed, in particular, on the work performed to establish standards for the exposure of people bearing AIMDs to electromagnetic fields, on studies in the context of EMP simulator and also on studies achieved for UHF frequency range. The effects of HPM/UWB pulses on an ICP were investigated and both synchronous and asynchronous pacing modes were tested. The experimental results will also be presented.Plasma Science (ICOPS), 2013 Abstracts IEEE International Conference on; 01/2013
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ABSTRACT: The maximum frequency range limit is investigated for the dielectric property of human body tissues to be fitted with the Debye dispersion of up to three poles. The dielectric properties of the human body tissues compiled by Gabriel in the form of the 4-pole Cole-Cole models are reformulated into the Debye models by means of a weighted least squares method (W-LSM). It has been found that three-pole Debye function can model permittivity over the broad frequency range of five orders of magnitude, e.g., from 1 MHz to 100 GHz or from 100 kHz to 10 GHz within the root mean square error of several %.IEEE Microwave and Wireless Components Letters 02/2012; 22(2):73-75. · 2.24 Impact Factor
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ABSTRACT: We propose a dispersive finite-difference time domain(FDTD) algorithm suitable for the electromagnetic analysis of the human body. In this work, the dispersion relation of the human body is modeled by a quadratic complex rational function(QCRF), which leads to an accurate and efficient FDTD algorithm. Coefficients(involved in QCRF) for various human tissues are extracted by applying a weighted least square method(WLSM), referred to as the complex-curve fitting technique. We also presents the FDTD formulation for the QCRF-based dispersive model in detail. The QCRFbased dispersive model is significantly accurate and its FDTD implementation is more efficient than the counterpart of the Cole-Cole model. Numerical examples are used to show the validity of the proposed FDTD algorithm.The Journal of Korean Institute of Electromagnetic Engineering and Science. 01/2012; 23(1).