Tetra-polar 8-point tactile electrodes
According to Ohm's law, two electrodes of voltage and current are needed to get resistance. Since they should be attached at each end of the object, a total of 4 electrodes are needed. It is called Double electrodes method when the voltage and current electrode are bound together, and Tetra electrodes method when they are separated. Tetra-electrodes method is commonly used for resistance measurement because the double electrodes method causes a large contact resistance.
The earlier body composition analyzers used a 4?point electrodes method by connecting the 4 electrodes to each body part. 4-point electrodes method engages one side of the body, connecting each current and voltage electrode to the left arm and left foot only. This method only measures one impedance value, and identifies the body as one cylinder. As the importance of segmental analysis grows, new technology enabling the body to be divided into 5 cylinders and analyze the composition of these segments is required. Theoretically to get the impedance values of 5 cylinders, a total of 20 conductivity points are needed, 4 points per part. InBody is the first body composition analyzer in the world that successfully came out with tetra-polar 8-point electrodes method allowing for segmental impedance measurements (DSM-BIA method). InBody's 8-point electrodes method is the core technology which makes it possible to check the impedance values of the 5 body cylinders with only 8 points through DSM-BIA method