Method and system for electrode impedance measurement
First Claim
1. A device for the simultaneous measurement of electroencephalogram (EEG) signals and electrical impedance of applied (EEG) electrodes comprising:
- at least three electrodes adapted to be attached to a subject, at least one electrode being for electrical grounding, at least one electrode providing a reference signal, and at least one EEG measurement electrode for acquisition of a physiological signal;
a processor for collection of the physiological signal and determining the electrical impedance of each electrode individually;
a variable current source capable of progressively increasing and decreasing electrical current for impedance measurement into the individual electrodes steadily over a period of time; and
a monitor to display the EEG physiological signal and calculated electrical impedance for each electrode utilized.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention relates to measuring electrical impedance, and particularly to measuring impedance of electrodes used to acquire physiological signals. The measurement of electrode impedance is typically performed to ensure proper electrode-to-skin contact, and thus verify the quality of the acquired signals. Electrode-to-skin contact impedance has also clinical utility for monitoring, diagnosis, prognosis or treatment, as it can be used to measure skin conductivity, which is function of physiological processes. The present invention relates in particular to a substantially continuous method for performing such measurement. The measurement is performed in such a way that it does not affect the bioband, the range (or ranges) of frequencies that contains components used for diagnostic, prognostic, triage, and/or treatment purposes. The present invention therefore performs this impedance measurement without affecting the physiological signal while allowing for uninterrupted monitoring of said signal.
-
Citations
19 Claims
-
1. A device for the simultaneous measurement of electroencephalogram (EEG) signals and electrical impedance of applied (EEG) electrodes comprising:
-
at least three electrodes adapted to be attached to a subject, at least one electrode being for electrical grounding, at least one electrode providing a reference signal, and at least one EEG measurement electrode for acquisition of a physiological signal; a processor for collection of the physiological signal and determining the electrical impedance of each electrode individually; a variable current source capable of progressively increasing and decreasing electrical current for impedance measurement into the individual electrodes steadily over a period of time; and a monitor to display the EEG physiological signal and calculated electrical impedance for each electrode utilized. - View Dependent Claims (2, 3, 4, 5, 13)
-
-
6. A method for simultaneously measuring electroencephalogram (EEG) signals and electrical impedance of applied EEG electrodes comprising the steps of:
-
placing at least one grounding electrode on a subject; placing at least two separate measurement EEG electrodes on a subject at distinct locations, to acquire at least one physiological signal corresponding to the voltage differential between the two measurement electrodes; supplying and maintaining a first electrical current for impedance measurement to the first measurement electrode; acquiring a first physiological signal from said subject using an acquisition device connected to the two measurement electrodes; measuring a first amplitude of at least one frequency component corresponding to at least one of the current source frequency component from the first physiological signal; calculating a first electrical impedance of the first measurement electrode based at least in part on the measured first amplitude of at least one frequency component corresponding to at least one of the current source frequency component from the first physiological signal; supplying a progressively increasing second electrical current for impedance measurement to the second measurement electrode steadily over a period of time; acquiring a second physiological signal from said subject; measuring a second amplitude of at least one frequency component corresponding to at least one of the second current source frequency from the second physiological signal; calculating an electrical impedance of the second measurement electrode based at least in part on the measured second amplitude from the second physiological signal; reducing progressively the amplitude of the second electrical current for impedance measurement supplied to the second measurement electrode steadily over a period of time; comparing the calculated first and second electrode impedances against predetermined thresholds; and adjusting electrodes whose calculated electrical impedance exceeds the predetermined threshold by reapplying conductive fluid to the electrode(s), moving or repositioning the electrode(s), or replacing the electrode(s). - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
-
14. A method for simultaneously Measuring electroencephalogram (EEG) signals and electrical impedance of applied EEG electrodes comprising the steps of:
-
placing at least one grounding electrode on a subject; placing at least two separate measurement EEG electrodes on a subject at distinct locations, to acquire at least one physiological signal corresponding to the voltage differential between the two measurement electrodes; supplying a progressively increasing first electrical current for impedance measurement to the first measurement electrode steadily over a period of time; acquiring a first physiological signal from said subject using an acquisition device connected to the two measurement electrodes; measuring a first amplitude of at least one frequency component corresponding to at least one of the current source frequency component from the first physiological signal; calculating a first electrical impedance of the first measurement electrode based at least in part on the measured first amplitude of at least one frequency component corresponding to at least one of the current source frequency component from the first physiological signal; reducing progressively the amplitude of the first electrical current for impedance measurement supplied to the first electrode steadily over a period of time; supplying a progressively increasing second electrical current for impedance measurement to the second measurement electrode steadily over a period of time; acquiring a second physiological signal from said subject; measuring a second amplitude of at least one frequency component corresponding to at east one of the second current source frequency from the second physiological signal; calculating a second electrical impedance corresponding to the second measurement electrode based at least in part on the measured second amplitude of at least one frequency component corresponding to at least one of the current source frequency component from the first physiological signal; reducing progressively the amplitude of the second electrical current for impedance measurement supplied to the second measurement electrode steadily over a period of time; comparing the calculated first and second electrode impedances against a predetermined threshold; and adjusting electrodes whose calculated electrical impedance exceeds the predetermined threshold by reapplying conductive fluid to the electrode(s), moving or repositioning the electrode(s), or replacing the electrode(s). - View Dependent Claims (15, 16, 17, 18, 19)
-
Specification