Steffen Kaufmann develops a method for improved instrumentation of transfer impedance measurement, focusing on its application in electrical impedance tomography (EIT). The optimization is achieved by increasing the signal-to-noise ratio. At the same time, the method enables spectroscopic multi-frequency measurements with resolution in both magnitude and phase. The author develops and evaluates a bioimpedance measurement system (BMS), which is expanded into a multi-frequency EIT system and used for various measurements on resistance and tank phantoms, as well as for visualizing respiration. The conclusion includes the design of a parallel multi-frequency active electrode EIT system.