Development of Bioelectric Impedance Measurement System Using Multi-Frequency Applying Method

Abstract

In order to measure the segmental impedance of the body, a bioelectrical impedance measurement system (BIMS) using multi-frequency applying method and two-electrode method was implemented in this study. The BIMS was composed of constant current source, automatic gain control, and multi-frequency generation units. Three experiments were performed using the BIMS and a commercial impedance analyzer (CIA). First, in order to evaluate the performance of the BIMS, four RC circuits connected with a resistor and capacitor in serial and/or parallel were composed. Bioelectrical impedance (BI) was measured by applying multi-frequencies -5, 10, 50, 100, 150, 200, 300, 400, and 500 KHz -to each circuit. BI values measured by the BIMS were in good agreement with those obtained by the CIA for four RC circuits. Second, after measuring BI at each frequency by applying multi-frequency to the left and right forearm and the popliteal region of the body, BI values measured by the BIMS were compared to those acquired by the CIA. Third, when the distance between electrodes was changed to 1, 3, 5, 7, 9, 11, 13, and 15 cm, BI by the BIMS was also compared to BI from the CIA. In addition, BI of extracellular fluid (ECF) was measured at each frequency ranging from 10 to 500 KHz. BI of intracellular fluid (ICF) was calculated by subtracting BI of ECF measured at 500 kHZ from BI measured at seven frequencies ranging from 50 to 500 KHz. BI of ICF and ECF decreased as the frequency increased. BI of ICF sharply decreased at frequencies above 300 KHz.

Multi-dimensional grating interferometer based on fibre-fed measurement heads arranged in Littrow configuration

“…Therefore, for multi-dimensional measurements a larger number of measurement heads is needed. In order to reduce the complexity of machines, it can be favourable to combine multi-dimensional gratings with multi-dimensional encoder heads to fulfill Abbe's criteria [4]. The most compact way to get the diffraction order signal is to use a Littrow configuration where the incident and the diffracted beams are coincident at a certain angle, depending on the wavelength and the grating pitch [5].…”

Bioelectrical Impedance Analysis at Inner Forearms of the Human Body using Bioelectrical Impedance Measurement System

“…Bioelectrical impedance measurement system (BIMS) was described in our previous paper [13]. BIMS consisted of a main control unit (MCU, ATmega128, NewTeC Co., Korea), multi-frequency generation (MFG) unit, automatic gain control (AGC) unit, constant current source (CCS), electrode, preprocessing part, and PC.…”

Bioelectrical Impedance Analysis at Popliteal Regions of Human Body using BIMS

“…BIMS was described in detail in our previous paper [11]. BIMS consisted of a main control unit (MCU, ATmega128, NewTeC to set parameters such as starting frequency, incremental The measured BI was displayed in the form of bode plots and tables, and stored in the PC.…”

“…They reported that PA values were 7.322º in healthy subjects and that PA values had a significant positive correlation with body mass index (BMI) (r = 0.011, P < 0.001). Kim et al [11] developed a BIMS, with a multi-frequency analysis method and two-electrode method, for measuring the BI in the body segments.…”

“…Many studies on BIA have been carried out to analyze the composition of living tissues or biological samples [6][7][8][9][10][11].…”