Design of A Microcontroller Based Cole-Cole Impedance Meter for Testing Biological Tissues
Complex impedance measurement of biological systems is gaining wide popularity in determining the pathological and physiological status of tissues in research areas such as; body fat content, blood freshness, tissue ischemia, skin hydration, and etc. In this study we designed a four-probe, multi-frequency, portable Cole-Cole impedance meter based on the magnitude-ratio and phase-difference detection principles. The system is built around a sine-wave generator, a voltage controlled current source, a phase-gain detector and a microcontroller unit. The Cole-Cole parameters, namely R0, R ∞ , fc and α and the extracellular fluid and intracellular fluid resistances, Re and Ri are also calculated and directly displayed by the device. Device accuracy is checked against the HP 4284A LCR meter under different RC test loads that simulate physiological measurements.
Keywordsbioimpedance magnitude-ratio and phase-difference detection Cole-Cole parameters
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