A Novel Method to Estimate Body Capacitance to Ground at Mid Frequencies

The capacitance of the human body to ground is included in the equivalent circuit of some capacitive sensors. It is a recognized source of interference in bioimpedance and biopotentials measurements, and a relevant parameter to model electrostatic discharges (ESD) and to predict the effects of electromagnetic fields on the human body. This paper describes a method to estimate that impedance from 10 kHz to 1 MHz based on a very simple fixture intended for impedance analyzers that can measure only ungrounded impedances. Relevant criteria to design that fixture and parameters that limit its performance are first assessed by measuring known capacitors and later applied to measurements in human subjects.