A New Method for Measurement of Bioelectrical Impedance

The paper describes the theory and practical implementation of a four-electrode method for measuring complex bioimpedance of local tissue. This new method adopts three independent voltages V
_in+
, V
_in-
, V
_R
respectively from the two voltage electrodes and a sample resistor R, which is connected in serial with one of the two voltage electrodes. Theoretical analysis shows that real part Z
_real
and imaginary part Z
_imag
of the complex impedance between two voltage electrodes can be acquired from the modular ratios (|V
_in+
|/|V
_R
|), (|V
_IN-
|/|V
_R
|) and phase difference (
_IN+
-
_R
), (
_{IN +}
-
_R
) through simple calculation. The problems with the conventional methods are avoided with this novel technique.