Bioelectric Impedance Measurements

Abstract

Bioelectric tissue impedance measurement to determine or infer biological information has a long history dating back to before the turn of the century . BEI measurements are commonly used in, cardiac measurement , body composition, and peripheral blood flow that we will cover it in our project. Impedance plethysmography is a measurement technique that measures the change in blood volume ( venous blood volume as well as the pulsation of the arteries )for a specific body segment . this report will describes briefly the anatomy of the blood vessel in the limb, the biomechanics of blood flow, and the approximation model of the human limb. In order to apply this technique we want to construct a constant current source (2 ma, 50KHz) this current will apply to the patient limb by two electrodes, then an electrical signal will be taken by another tow electrodes as a result of changing in impedance according to the blood movement . a full descriptions for applying this technique in successful way will be considered in this report.