A Study of Using Tetrapolar and Eight-Polar Electrode System to Detect Fat by Bioelectrical Impedance Analysis (BIA) Technique

Abstract

Bioelectrical Impedance Analysis (BIA) is a technique to estimate the total fat mass of a body. Tetrapolar and eight-polar electrode system are conventionally used to measure transimpedance computed from skin voltage information. Each system has different sensitivity of voltage measurement to the presence of fat in the different part of the body. Consequently, each system may have limitations to detect fat residing in different regions. In this studies, these limitations were investigated by simulation. Three current schemes and three measurement positions were simulated to detect the increase of fat in the whole body. The result showed that the tetrapolar system was able to detect fat only the half limb of the body. On the other hand, the eight-polar system can detect fat in the whole body. However, fat residing in the arms, the hip, the thighs, and the bottom may influence the accuracy of the fat mass estimation, because the bioimpedance of these regions is used as both the bioimpedance of the trunk and that of the legs or the arms. It is also found that the breast which is mostly fat had less influence in the estimation. This means the estimation for the fat mass of women may be not accurate and may be less in correlation to the breast size as well.