Since the wavelength of the electric field in the different layers is much larger than the dimensions of the electrodes, a quasi-static electrical conduction model was applied to solve for the electric field in the saline solution (15 (link), 44 ). The finite element simulation using the 3D AC/DC module of COMSOL Multiphysics was then performed for impedance measurements in the model. After obtaining the solution for the electric potential, boundary integration was used to determine electric current and consequently obtaining the electric impedance. With the AC/DC module of COMSOL it is possible to obtain the solution for the electric impedance at different frequencies. Simulations were repeated for frequencies exponentially distributed from 10 Hz to 1 MHz, to characterize the frequency response and the bioimpe-dance readings were recorded (46 ). The whole process was performed for different models with different number of surface electrodes (28 , 32 (link), 44 and 48 ) as well as different ground and terminal electrode dimensions (rterminal = 1, 2, 2.5 mm and rground = 0.5, 1 mm).
Finally, to find the optimized electrode configuration for the measurement set-up, the contribution of the different parts of the model, especially the venous segment, to the impedance measured between the surface and the ground electrode (total impedance) was computed.
Finally, to find the optimized electrode configuration for the measurement set-up, the contribution of the different parts of the model, especially the venous segment, to the impedance measured between the surface and the ground electrode (total impedance) was computed.
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