Electrical bioimpedance measurement: methods and equivalent circuits

Measurement of electrical bioimpedance (EBI) of biological objects with specific dielectric properties, complicated geometry, and relatively fast time variations, presents a complicated task, which can be solved using corresponding measurement methods and dedicated measurement equipment. Still selection of the measurement method as well as interpretation of the measurement results and selecting of the equivalent circuits remain after the scientist. In this paper some EBI-specific information is given concerning the properties of the most commonly used measurement methods and certain equivalent circuits of the EBI. Some of them, as functional nonlinearities, are commonly not sufficiently discussed. Other of the peculiarities, as the time variation of the EBI, are described in the context of interpreting the measurement results.