US 4,944,301 A · Method for determining absolute current density through an implanted electrode

Abstract

A method for determining absolute current density through an implanted electrode measures the fundamental and harmonic components of an electrical current passing through the electrode and estimates the absolute current density from the ratio between the magnitude of the electrical current measured at one of the harmonics on the fundamental frequency. Another method of the invention applies a wideband noise input voltage to the electrode 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. The methods may be practiced non-invasively.

Claims18

Dependent claims

A method for determining the absolute density of an electrical current passing through an electrode implanted in a body, comprising the steps of:

(a) applying a voltage waveform to said implanted electrode;
(b) measuring the distortion of said waveform introduced by the non-linear I-V characteristics of the interface between said electrode and the tissue of said body;
and
(c) estimating the absolute current density of said electrical current through said electrode based on the characteristics of said distortion.

1 more element

A method for determining the absolute current density of an electrical current passing through an electrode implanted in a body, comprising the steps of:

(a) applying a wideband noise input voltage to the electrode;
(b) measuring the spectrum of the input voltage and the output current to determine V.sub.1 (jw) and I.sub.1 (jw) respectively;
(c) computing the transfer function ##EQU3## (d) increasing the magnitude of the input voltage applied in step (a);
(e) measuring the spectrum of the input voltage and the output current to determine V.sub.2 (jw) and I.sub.2 (jw) respectively;
(f) computing the transfer function ##EQU4## for the increased magnitude input voltage;
(g) computing the difference between the transfer functions to yield D(jw)=H.sub.2 (jw)-H.sub.1 (jw);
and
(h) estimating the absolute current density from the difference transfer function D(jw).

5 more elements

Dependencies are inferred from the claim text.

Method for determining absolute current density through an implanted electrode

Life of this patent

Method for determining absolute current density through an implanted electrode

Life of this patent

Abstract

Claims18