%0 Journal Article
%T Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review
%A Tushar Kanti Bera
%J Journal of Medical Engineering
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/381251
%X Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends. 1. Introduction A living object such as an animal or plant is developed with cells and tissues arranged in three dimensional arrays. For example, the human body is a biological subject which is a very complex structure constructed by several living tissues [1] composed of the three-dimensional arrangement of human cells. The biological cells, containing intracellular fluids (ICF), cell membranes with or without cell wall, are suspended in the extracellular fluids (ECF) and show a frequency dependent behavior to an alternating electrical signal. Under an alternating electrical excitation, the biological cells and tissues produce a complex bioelectrical impedance or electrical bioimpedance [2¨C4] which depends on tissue composition and frequency of the applied ac signal [2¨C4]. Therefore the frequency response of the electrical impedance of the biological tissues is highly influenced by their physiological and physiochemical status and varies from subject to subject. Even the complex bioelectrical impedance varies from tissue to tissue in a particular subject and also varies with the change in its health status [5, 6] depending on the physiological
%U http://www.hindawi.com/journals/jme/2014/381251/