Effects of stray capacitance to ground in impedance measurements

Abstract

Inductive effects such as positive phase angles in impedance measurements have often confused the researchers when the material measured is nonmagnetic. When the measurement is based on auto-balancing bridge method and the measured material is a bulky sample, the capacitive coupling from sample to ground can cause some of these inductive effects. A model with four electrodes for bioimpedance measurements on the human body is analyzed considering the capacitive coupling from human body to ground. Impedance meters based on auto-balancing bridge cannot measure grounded impedances; to overcome this limitation, we will propose a method to estimate the stray capacitance to ground with these meters.