Bio-electrical impedance spectroscopy (EIS) electrical signals of low power of human tissue, relatively low frequencies (up to 1 MHz), as well as non-invasive method is important to distinguish the physiological state of organisms. Modelling of electrical properties of human skin in the standard laboratory conditions is an open theoretical, practical and clinical problem. The purpose of this study is twofold: 1) The analysis and decision on possible options under the new biophysical models of its electric characteristics, based on discrete-continuous model of frequency scaling; 2) From the literature known concept of frequency dependent negative dynamic electrical resistanceas used in the case of high frequency , bringing the total mpproach to modeling material.To measure bioimpendanse of the human skin was used instrument 1255 Frequency Response Analyser in combination with Solartron 1286 Pstat/Gstat, wodel considerably improves. Both objectives have in common that they stem from a dynamic aith suitable additional equipment. Due to the inadequacy of the software package ZView® for Windows in this case, for fitting data was used Levmar. Both packages are based on the Levenberg-Marquardt's nonlinear least squares algorithm. Mathematical and biophysical model presented as a unified continuous-discrete Cole - equation for impedance of the material. Measurements were done on human skin of the forearm, as the test system. The applied voltage is, inerval of the source fequency is and electrode diameters are 0.25 cm and 2 cm. In the paper shows that the standard continuous two- and three-component model of Cole bioimendanse human skin is fitted better than their discretized version, in all scales, for all the selected frequency steps. Assuming a negative value of active high-frequency electrical resistance, we have improved fit of the continuum model as compared to the previous continuous model about 10%.For here introduced the dynamic properties of the model, it is necessary to carry out as many new bio-medical and clinical analysis of different tissues.
Comments: 14 Pages.
[v1] 2016-07-08 05:33:10
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