Evaluation of the quality of electrode contact with a skin surface
View Patent ↗An instrument that utilizes body contact electrodes evaluates the quality of the connections made between the electrodes and the body. An electrode contact quality evaluation circuit performs the quality evaluation, such as by determining contact impedances for the electrodes. The corresponding contact quality of each electrode is conveyed to the user.
1. A system comprising:
an injection, a sense and a return skin-contacting electrode;
a current source, wherein the current source applies an AC test current to the injection skin-contacting electrode, the AC test current having a first polarity and a first magnitude,
a driven return coupled between the sense skin-contacting electrode and the return skin-contacting electrode, wherein the driven return accepts a return of the AC test current through the return skin-contacting electrode, wherein the driven return operates to keep a voltage at the sense skin contacting electrode centered at an isolated ground potential, and wherein the driven return generates a return current that is supplied to the injection skin-contacting electrode, the return current having a polarity opposite to the first polarity;
a processor, the processor executing instructions for performance of a simultaneous test to determine the quality of skin contact of both the injection and return skin-contacting electrodes, wherein execution of the instructions cause the processor to:
determine both a first differential voltage between the injection and sense skin-contacting electrodes and a second differential voltage between the sense and return skin-contacting electrodes after application of the AC test current and the return current; and
determine a first and second magnitude of a contact impedance for each of the injection and return skin-contacting electrodes, respectively, based on the first and second differential voltages, wherein the first and second magnitudes of contact impedance are representative of a quality of skin contact of the injection and return skin-contacting electrodes, respectively.
2. The system of claim 1 , wherein the processor is further caused to prevent use of the injection and/or return skin-contacting electrode in a patient-based measurement of electrical activity when the impedance of the injection and/or return skin-contacting electrode exceed a threshold impedance.
3. The system of claim 2 , wherein the patient-based measurement of electrical activity comprises: an electrocardiograph (ECG), an electroencephalograph (EEG), or an electromyography (EMG).