Mahdavi, Hadiseh

Rosell Ferrer, Francisco Javier

English

UPCommons. Portal del coneixement obert de la UPC

Simulation of a Magnetic Induction Method for Determining Passive Electrical Property Changes of Human Trunk Due to Vital ActivitiesHadiseh Mahdavi, Javier Rosell FerrerTechnical University of Catalunia (UPC) , Department of Electronic Engineering, Barcelona, SpainObjective:To evaluate the feasibility of a Magnetic Induction method formonitoring Breathing and Cardiac activity.Methods:The method is based on the creation of a primary magneticfield that will produce eddy currents in the trunk, thesecurrents will produce a secondary magnetic field that has to bedetected somewhere around the trunk [1]. This measuredsignal is a function of the conductivity and geometry of thetissue and the geometry of the excitation and detectionantennas. For a sample of material between an excitation coiland a sensing coil:And using the Magnetic Fields interface, the main governingequations are:( )0B jrB      Results:The induced eddy currents produced a secondary magneticfield, proportional to the properties of the tissues and thegeometry.The secondary magnetic field detected at the same planewhere the excitation coil is located, increases as frequencyrises. Since the conductivity of lungs is lower when inflated,the secondary magnetic field is lower in this mode.Conclusions:Results show that the changes in the passive electricalproperties of the lungs during breathing produce anoticeable change in the secondary magnetic fielddetected in the excitation plane.In addition safety issues have been studied to fulfill theinternational standards for limiting exposure to magneticfields.References:1. H. Griffiths, W. R. Stewart, and W. Gough, “Magneticinduction tomography. A measuring system forbiological tissues.,” Annals Of The New York AcademyOf Sciences, vol. 873, no. 1, pp. 335–345, 1999.2. International Commission on Non-Ionizing Radiation, “ICNIRP Guidelines for Limiting Exposure to Time-Varying Electric, Magnetic and Electromagnetic Fields (up to 300 GHz),” Health Physics, vol. 74, no. 4, pp. 494–522, 1998. Induced Current Density in  a Section of trunk 2 0 r eB Aj A H J     Specific absorption rate (SAR) has been calculated toensure the safety of the system according to theinternational standards [2].As shown, the SAR value is highest close to thesurface of the body and decreases when the distancebetween excitation coil and the trunk increases.The results show that, even considering the worst casefor exposing to the magnetic field, the maximumabsorption rate is orders of magnitude less than thesafety standard’s limits.

Simulation of a magnetic induction method for determining passive electrical property changes of human trunk due to vital activities

https://upcommons.upc.edu/bitstream/2117/17104/1/14115_mahdavi_poster.pdf

Simulation of a magnetic induction method for determining passive electrical property changes of human trunk due to vital activities

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