Connection quality assessment for EEG electrode arrays
Inventors
Grant, Alexander M. • Yi, Jianchun • Bachelder, Bradley G. • Woo, Raymond • Parvizi, Josef • Chao, Xingjuan
Assignees
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Publication Number
US-10285646-B1
Publication Date
2019-05-14
Expiration Date
Abstract
Systems, devices, and methods are provided to assess connection quality between the electrodes of a bioelectrical signal measurement and/or electrical stimulation device and the tissue, typically skin, of the subject. A test signal is provided to a first electrode, voltage differences between the first electrode and additional electrodes are determined, an impedance of the first electrode is determined based on the voltages differences, and the determined impedance indicates connection quality. This process is typically repeated for all of the electrodes to determine connection quality. The user or subject can be alerted if the connection quality is poor, and the bioelectrical signal that is recorded can be provided with data points indicating connection quality during the signal recording.
Core Innovation
The invention relates to a method of assessing quality of a connection between an electrical sensor or stimulator and tissue of a subject. The method provides an electrical sensor or stimulator comprising a plurality of electrodes and contacts the plurality of electrodes to tissue of a subject. A test signal is provided to the tissue through a first electrode of the plurality of electrodes.
With a processor coupled to the plurality of electrodes, at least one voltage difference is determined between the first electrode and another electrode in response to the test signal, wherein neither the first electrode nor the another electrode is a common ground or a common reference electrode. In this approach, a first voltage difference is determined between the first electrode and only a second electrode, and a second voltage difference is determined between the first electrode and only a third electrode, with none of the first, second, or third electrodes being a common ground or a common reference electrode.
With the processor, an impedance of the first electrode is determined in response to the determined at least one voltage difference. Determining the impedance includes determining a first impedance between the first electrode and only the second electrode and determining a second impedance between the first electrode and only the third electrode, then determining a lesser of the first and second impedances and assigning it as the determined impedance of the first electrode. Connection quality of the first electrode is deemed poor if the determined impedance exceeds a predetermined impedance threshold.
The method notifies one or more of the subject or a user when the connection quality is poor, using an output device coupled to the processor. The document further describes EEG/ECG/EMG and stimulation systems that tag or accompany measured and/or recorded bioelectrical signals with connection-quality data points, and describes notifying via an audio/visual alarm and presenting electrode status to a user interface, including examples of impedance tiers and impedance scaling.
Claims Coverage
The provided material identifies one independent claim directed to the connection-quality assessment method. Dependent members are described as refining parameters, electrode configurations, notification modality, and optional recording/tagging of bioelectrical signals.
Impedance from voltage differences without common ground/reference
Determining, with a processor coupled to the plurality of electrodes, at least one voltage difference between the first electrode and another electrode in response to the test signal, wherein the at least one voltage difference is determined with neither the first electrode nor the another electrode being a common ground or a common reference electrode, and where determining comprises determining a first voltage difference between the first electrode and only a second electrode and determining a second voltage difference between the first electrode and only a third electrode with neither the first, second, nor third electrodes being a common ground or a common reference electrode.
Lesser-of impedances used as first-electrode impedance
Determining, with a processor coupled to the plurality of electrodes, an impedance of the first electrode in response to the determined at least one voltage difference, wherein determining comprises determining a first impedance between the first electrode and only the second electrode in response to the first voltage difference, determining a second impedance between the first electrode and only the third electrode in response to the second voltage difference, determining a lesser of the first and second impedances, and assigning the lesser of the first and second impedances as the determined impedance of the first electrode.
Poor-connection notification when impedance exceeds threshold
Notifying, with an output device coupled to the processor, one or more of the subject or a user that connection quality of the first electrode is poor if the determined impedance of the first electrode is above a predetermined impedance threshold.
Across the independent claim, the main inventive coverage is the determination of voltage differences without a common ground or common reference electrode, using those voltage differences to derive an impedance for the first electrode as a lesser-of two computed impedances, and notifying the subject or user when that impedance exceeds a predetermined threshold.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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