Implementation of Bioelectric Impedance Measurement System using Multi-Frequency Applying Method and Two-Electrode Method

In order to measure the segmental impedance of the body, bioelectrical impedance measurement system (BIMS) was implemented in this study using multi-frequency applying method and two-electrode method. It was composed of constant current source unit, automatic gain control unit, and multi-frequency generation unit. Three experiments were executed using implemented BIMS and commercial impedance analyzer First, bioelectrical impedance (BI) was measured by applying multi-frequencies 5, 10, 50, 100, 150, 200, 300, 400, and 500 KHz – to each circuit after composing 4 RC circuits connecting resistance and capacitor in serial and parallel in order to evaluate the performance of BIMS. BI values as a function of frequency for 4 RC circuits were compared to those obtained by using CIA. Second, after measuring BI at each frequency by applying multi-frequency to the left or right region of forearm and popliteal of the body, BI values were compared to those acquired by CIA. Third, when the distance between two electrodes was changed to 1, 3, 5, 7, 9, 11, 13, and 15 cm, BI measured at each frequency from 10 to 500 KHz was also compared to that from CIA. Keywords—Bioelectrical Impedance, Impedance analyzer, Multi-frequency impedance meter, extracellular fluid, intracellular fluid.