Complex bioelectric impedance measurement system for the frequency range from 5 Hz to 1 MHz

Abstract-Analytic techniques that have been successfully em-ployed in materials cience, and to a lesser extent in the study of biologic systems, have potential for improving the applica-tion of bioelectric impedance provided that both real and imag-inary impedance components can be measured with sufficient accuracy over a given frequency range. Since biologic tissue, particularly animal tissue, is typically highly conductive, phase angles are small, making accurate measurements difficult. A practical four-terminal system employing commercial lock-in amplifiers is described and error sources and corrective tech-niques are discussed. Keywords--Electric conductivity, Electronic instrumentation