On the Effect of Body Capacitance to Ground in Tetrapolar Bioimpedance Measurements

摘要: Tetrapolar bioimpedance measurements on subjects have long been suspected of being affected by stray capacitance between the subjects' body and ground. This paper provides a circuit model to analyze that effect in frequency range from 100 Hz 1 MHz order identify relevant parameters when impedance is measured applying voltage measuring both resulting current potential difference two points surface volume conductor. The proposed includes each electrode input differential amplifier. When common values for are assumed, simplified predicts: 1) frequency-independent gain (scale factor) error; 2) inductive artifacts, is, increases with increasing may include positive angle phases; 3) resonance can affect well below MHz. In addition ground, determine those errors “low-current” Experimental results confirm theoretical predictions show effects several additional resonances above also depend