System and method for testing contact quality of electrical-biosignal electrodes
Inventors
Gunasekar, Aswin • Benedek, Ferenc • Kokavecz, János • Braun, Gabor
Assignees
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Publication Number
US-11432770-B2
Publication Date
2022-09-06
Expiration Date
Abstract
One variation of a method for testing contact quality of electrical-biosignal electrodes includes: outputting a drive signal through a driven electrode, the drive signal comprising an alternating-current component oscillating at a reference frequency and a direct-current component; reading a set of sense signals from a set of sense electrodes at a first time; calculating a first combination of the set of sense signals; calculating a first direct-current value comprising a combination of the first combination and the direct-current component of the drive signal at approximately the first time; and at a second time succeeding the first time, shifting the direct-current component of the drive signal output by the driven electrode to the first direct-current value.
Core Innovation
The invention provides an electroencephalography method in which a headset-integrated driven electrode outputs a drive signal including an alternating-current component oscillating at a reference frequency and a direct-current component. During a test period, the method reads sense signals from sense electrodes while coordinating which electrode subsets correspond to selected channels of interest. The method uses the sense signals to compute and apply a virtual reference signal and to record differences for an electroencephalography test result.
A central aspect is that the method adjusts the direct-current component of the drive signal using a first linear combination of sense signals and, when abnormal contact is detected, uses additional signal-dependent calculations while excluding a first signal component oscillating at the reference frequency. The approach includes calculating a virtual reference signal as a function of a second set of sense signals and recording differences between a first set of sense signals and the virtual reference signal.
The invention also manages electrode contact states during the test period by detecting abnormal contact between a user's skin and a sense electrode based on sense signals excluding a component oscillating at the reference frequency. In response, the method can deactivate a sense electrode and can generate an electronic notification and transmit it to an external computing device accessible by a biosignal test administrator, and annotate or store digital electroencephalography test results reflecting contact states over durations.
Claims Coverage
The independent claims cover a coordinated EEG test method with selection of channels of interest, multiple sense-electrode subsets, driven-electrode signaling at a reference frequency plus a DC component, linear-combination-based DC adjustment, virtual reference computation and difference recording, and abnormal-contact detection based on excluding a reference-frequency oscillatory component, with contact-state response including deactivation and optional external notifications. Across the independent claims, there are three core inventive feature areas: virtual reference and difference recording while adjusting DC, reference-frequency-excluded abnormal-contact detection and deactivation, and time-separated linear-combination DC updates that incorporate excluding an abnormal-contact sense signal component.
Virtual reference from sense-electrode subsets with DC adjustment
receiving selection of a set of channels of interest; selecting a first subset of sense electrodes corresponding to the set of channels of interest; selecting a second subset of sense electrodes differing from the first subset; during a test period, outputting a drive signal through a driven electrode comprising an alternating-current component oscillating at a reference frequency and a direct-current component; during a first duration, reading a first set of sense signals and reading a second set of sense signals; adjusting the direct-current component of the drive signal according to a first linear combination of the first subset of sense signals; calculating a virtual reference signal as a function of the second set of sense signals; and recording differences between the first set of sense signals and the virtual reference signal.
Abnormal skin-to-electrode contact detection with deactivation
receiving selection of a set of channels of interest; selecting a first subset of sense electrodes corresponding to the set of channels of interest; selecting a second subset of sense electrodes differing from the first subset; during a test period, outputting a drive signal through a driven electrode including an alternating-current component oscillating at a reference frequency and a direct-current component; reading a first set of sense signals and reading a second set of sense signals; in response to a second sense signal read from a second sense electrode excluding a first signal component oscillating at the reference frequency, detecting abnormal contact between the user's skin and the second sense electrode; and in response to detecting abnormal contact, deactivating the second sense electrode.
Time-separated DC component adjustment using linear combinations with reference-frequency exclusion
receiving selection of a set of channels of interest; selecting a first subset of sense electrodes corresponding to the set of channels of interest; during a test period, outputting a drive signal including an alternating-current component oscillating at a reference frequency and a direct-current component; over a first duration, reading a first set of sense signals, calculating a first linear combination of the first set of sense signals, and adjusting the direct-current component of the drive signal according to the first linear combination; over a second duration, reading a second set of sense signals; in response to a second sense signal read from a first sense electrode excluding a first signal component oscillating at the reference frequency, detecting abnormal contact between the user's skin and the first sense electrode; calculating a second linear combination of the second set of sense signals less the second sense signal; and adjusting the direct-current component of the drive signal according to the second linear combination.
Collectively, the independent claims require driven-electrode signaling with an alternating-current component at a reference frequency plus a direct-current component, selecting subsets of sense electrodes tied to channels of interest, adjusting the direct-current component via linear combinations, computing a virtual reference in one independent claim and recording differences against the virtual reference, and detecting abnormal contact using sense signals with exclusion of a reference-frequency oscillatory component, with deactivation of affected sense electrodes and optional notification and recording refinements in dependent claims.
Stated Advantages
Documented Applications
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