METHOD FOR DETERMINING ABSOLUTE CURRENT DENSITY

摘要

A method for determining absolute current density through an implanted electrode (16) measures the fundamental and harmonic components of an electrical current passing through the electrode (16) and estimates the absolute current density from the ratio between the magnitude of the electrical current measured at one of the harmonics and the fundamental frequency. Another method of the invention applies a wideband noise input voltage to the electrode (16) under investigation and measures the spectrum of the input voltage and output current to determine a first transfer function. A second transfer function representing an increase magnitude of wideband noise input voltage is also obtained. A difference transfer function is computed and used to determine absolute current density through the electrode (16). The methods may be practiced non-invasively.