Transmission of Electromagnetic Power through a Biological Medium
Primary goal of this work is to study transmission of EM power through a multilayered biological medium. For a particular case study, EM power transmission from an external transmitter to a coupled receiver implanted inside a biological medium simulating a human body is studied to find solutions for factors such as optimum transmission frequency and excitation current. Different aspects of interaction of EM waves with biological bodies and tissues are discussed. Two major factors that may affect transmission of EM power through a biological body are absorption and reflection of EM waves. A simulation in which exact Maxwell's equations are solved to find E field distribution in cross-sectional planes of a human body with the implanted receiver takes into account both absorption and reflection accurately. A simplified model for a human body with an implanted receiver and an external transmitter is developed here. Main motivation is to find E field distribution throughout the model and find energy density coupling between the transmitter and the receiver regions. Edge based finite element simulations are carried out on the model for a number of frequencies between 1 kHz and 9 GHz and frequency dependent values for EM properties such as relative permittivity and conductivity of biological tissues are used for all the simulations. Energy density coupling, E field coupling and S parameters showing reflection at the excitation port are obtained from the simulated results. Energy coupling is found to be almost constant with values near 0.01 between 1 kHz and 500 MHz. Current densities are below the thermal safe current density level even for an excitation current density of 3x106 A.m-2 in the transmitter. Although model used for simulation is simplistic, the results obtained are useful to study EM power losses in a multilayered biological medium. Results can be applied to find safe limits of excitation current density for transmitting EM power through a biological medium such as a human body without causing any damage due to heating.
Advisor:Pratul Ajmera; Martin Feldman; Ashok Srivastava
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Keywords:electrical computer engineering
Date of Publication:09/02/2003