U.S. patent application number 17/203464 was filed with the patent office on 2022-02-03 for connection quality assessment for eeg electrode arrays.
The applicant listed for this patent is CeriBell, Inc.. Invention is credited to Bradley G. BACHELDER, Xingjuan CHAO, Alexander M. GRANT, Josef PARVIZI, Raymond WOO, Jianchun YI.
Application Number | 20220031248 17/203464 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-03 |
United States Patent
Application |
20220031248 |
Kind Code |
A1 |
GRANT; Alexander M. ; et
al. |
February 3, 2022 |
CONNECTION QUALITY ASSESSMENT FOR EEG ELECTRODE ARRAYS
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.
Inventors: |
GRANT; Alexander M.;
(Redwood City, CA) ; YI; Jianchun; (San Jose,
CA) ; BACHELDER; Bradley G.; (Redwood City, CA)
; WOO; Raymond; (Los Altos, CA) ; PARVIZI;
Josef; (Palo Alto, CA) ; CHAO; Xingjuan; (Palo
Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CeriBell, Inc. |
Mountain View |
CA |
US |
|
|
Appl. No.: |
17/203464 |
Filed: |
March 16, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16363159 |
Mar 25, 2019 |
10980480 |
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17203464 |
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15906375 |
Feb 27, 2018 |
10285646 |
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16363159 |
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International
Class: |
A61B 5/00 20060101
A61B005/00; A61N 1/37 20060101 A61N001/37; A61N 1/02 20060101
A61N001/02; A61N 1/36 20060101 A61N001/36; A61B 5/24 20060101
A61B005/24; A61B 5/287 20060101 A61B005/287; A61B 5/369 20060101
A61B005/369 |
Claims
1. A method of assessing quality of a connection between an
electrical sensor or stimulator and tissue of a subject, the method
comprising: (a) providing an electrical sensor or stimulator
comprising a plurality of electrodes; (b) contacting the plurality
of electrodes to tissue of a subject; (c) providing a test signal
to the tissue of the subject through a first electrode of the
plurality of electrodes; (d) determining, with a processor coupled
to the plurality of electrodes, a voltage difference between the
first electrode and only one other electrode of the plurality of
electrodes in response to the test signal, wherein the voltage
difference is determined with neither the first electrode nor the
only one other electrode being a common ground or a common
reference electrode; (e) determining, with a processor coupled to
the plurality of electrodes, an impedance of the first electrode in
response to the determined voltage difference between the first
electrode and the only one other electrode of the plurality of
electrodes; (f) repeating steps (d) and (e) for the first electrode
and other electrodes of the plurality of electrodes; and (g)
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.
Description
CROSS-REFERENCE
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/363,159, filed Mar. 25, 2021, now U.S. Pat.
No. ______; which is a continuation of U.S. patent application Ser.
No. 15/906,375, filed Feb. 27, 2018, now U.S. Pat. No. 10,285,646;
which are incorporated herein by reference in their entirety and to
which applications we claim priority under 35 U.S.C. .sctn.
120.
BACKGROUND
[0002] The present disclosure relates generally to the field of
measuring electrical signals from living subjects (e.g., electrical
signals indicative of brain activity and/or heart activity) and
providing electrical signals to living subjects (e.g., for
neurostimulation or muscle stimulation). In particular, the present
disclosure relates to systems, devices, and methods for calibrating
the connection between the electrode(s) of such measurement and/or
stimulation devices and the tissue of the living subject, typically
skin.
[0003] The ability to measure signals from a living subject (e.g.,
those relating to the living subject's bodily functions) can be
beneficial for many medical and diagnostic applications. Electrical
signals from the brain (i.e., electroencephalography (EEG) signals)
can be measured to ascertain brain activity related to abnormal
brain function, to monitor spatial and/or temporal progression of
brain disease, to aid surgical or nonsurgical intervention by
localizing disease-sites in the brain, to monitor brain activity of
a healthy subject or a subject of unknown health status when the
subject experiences a variety of stimuli and lack of stimuli, etc.
Electrical signals from the heart (i.e., electrocardiography (ECG
or EKG) signals) can be measured to determine the rate and rhythm
of heart beats, the size and position of the heart chambers, the
presence of any damage to the cardiac and/or myocardial tissue, the
effect of cardiac drugs, the function of cardiac pacing devices,
etc. Electrical signals from skeletal muscles (i.e.,
electromyography (EMG) signals) can be measured to determine
medical abnormalities with the skeletal muscles, their activation
levels, their recruitment order, to analyze the biomechanics of
movement, etc.
[0004] The ability to deliver electrical signals to a living
subject can also be beneficial for many medical and therapeutic
applications. Electrical signals may be delivered to the heart to
pace the rate and rhythm of heart beats, and in some cases, for
defibrillation of the heart. Electrical signals may be applied to
various parts of the nervous system to upregulate and/or
downregulate various nerve and nerve-related functions. For
example, the spinal cord may be stimulated to treat pain,
facilitate injury rehabilitation, restore cardiac function, and
lower blood pressure, among other indications. The peripheral
nerves may also be stimulated to treat pain, facilitate injury
rehabilitation, treat incontinence, and lower blood pressure, among
other indications. Electrical signals may be delivered to the
skeletal muscles to diagnose responsiveness, facilitate injury
rehabilitation, accelerate muscle recovery, improve metabolism,
tone skeletal muscle tissue, and as an alternative to
weight-bearing exercise, among other purposes. In some cases, the
electrical signals delivered may be varied in accordance with other
electrical signals measured to provide a form of feedback
therapy.
[0005] The measurement of electrical signals from a living subject
and the delivery of electrical signals are often performed through
connection(s) between measurement and/or stimulation electrode(s)
and tissue of a patient. In many cases, the connection will be
between the skin and the electrode(s). For example, EEG headsets
contact EEG electrodes with the scalp of the subject, ECG
electrodes are typically contacted to skin on the chest of a
subject, EMG electrodes are typically contacted to skin over the
target skeletal muscles, and, in some cases, nerves and muscles may
be stimulated externally from external electrode(s) contacting skin
adjacent the target nerves and/or muscles. The connection between
the electrode(s) and skin may not always be ideal for many
reasons--such as skin moisture and quality not being ideal for
electrode contact, the presence of hair, the presence of regions of
thickened and/or hardened skin, the presence of dirt, undesired
fluids, or other residue, to name a few examples. Hence, the
electrode-to-skin connection may often need to be assessed so that,
if appropriate, a medical professional may re-position the
electrode, clean the skin and/or electrode, or otherwise re-adjust
the connection as needed to have a more ideal electrode connection
for the intended measurement and/or diagnosis. In other cases, the
connection will be between the electrode(s) and other tissue. For
example, the connection may be between dura mater in the epidural
space and the electrode lead(s) for spinal cord simulators, between
the pacing lead(s) and cardiac tissue for pacing devices, the
electrode(s) and skeletal muscle tissue for skeletal muscle
stimulators, etc. Connection quality between the electrode(s) and
the tissue may again be important to obtain high quality
measurements and/or provide the stimulation at the desired
levels.
[0006] In many cases, the connection between measurement or
stimulation electrode(s) and tissue of the subject is assessed
before measurement and/or stimulation. Measurement and/or
stimulation, in some cases, however, may be long-term and
continuous. For example, measurements and/or stimulation may be
undertaken for at least 30 minutes, at least an hour, at least a
day, or at least a week or more in many applications. And,
connection quality may deteriorate or at least vary over the long
measurement and/or stimulation time period. Many currently used
connection quality assessment methods, however, cannot determine
connection quality while measurement and/or stimulation are
occurring. For example, many connection quality assessment methods
depend on the use of a further reference electrode and/or reference
current, which in many cases cannot be present when measurement
and/or stimulation are undertaken.
[0007] There are therefore needs for improving the way the
connection quality between the electrodes of various measurement or
stimulation devices is assessed. There are also needs for
connection quality assessments methods that are usable concurrently
with measurement and/or stimulation, so that electrode connections
can be re-adjusted as necessary throughout the desired measurement
and/or stimulation time period, the measurement and/or stimulation
can be dynamically adjusted based on the current connection
quality, the measurement and/or stimulation signal can be recorded
along with connection quality assessment to provide signal
recordings with more data points for later analysis, to name a few
desirable purposes.
SUMMARY
[0008] The present disclosure relates generally to the field of
measuring electrical signals detected from living subjects (e.g.,
electrical signals indicative of brain activity and/or heart
activity) and providing electrical signals to living subjects
(e.g., for neurostimulation or muscle stimulation). In particular,
the present disclosure relates to systems, devices, and methods for
calibrating the connection between electrode(s) of such measurement
and/or stimulation devices and the tissue of the living subject,
typically skin. An exemplary measurement and/or stimulation
apparatus may comprise a plurality of electrodes configured to
contact the skin of a subject to measure and/or convey one or more
electrical signals. Voltage differentials between the different
electrodes may be used, according to embodiments of the present
disclosure, to determine impedances associated with the electrodes.
The determined impedances can provide an indicator for connection
quality, and, if connection quality is poor, the apparatus may
notify the subject or other user and may record connection quality
data points in parallel with measured electrical signals. Hence,
the subject or other user may be prompted to improve connection
quality and the reliability of the measured electrical signals, and
medical professionals may take into account the record of
connection quality while later analyzing the electrical signals
that are measured and recorded.
[0009] Aspects of the present disclosure provide methods of
assessing quality of a connection between an electrical sensor or
stimulator and tissue of a subject. An electrical sensor or
stimulator may be provided (step (a)). The electrical sensor or
stimulator may comprise a plurality of electrodes, not including a
common ground or reference electrode. The plurality of electrodes
may be contacted to tissue of a subject (step (b)). A test signal
may be provided to the tissue of the subject through a first
electrode of the plurality of electrodes (step (c)). At least one
voltage difference between the first electrode and a second
electrode may be determined in response to the test signal (step
(d)). An impedance of the first electrode may be determined in
response to the at least one voltage difference (step (e)). One or
more of the subject or a user may be notified that connection
quality of the first electrode is poor if the determined impedance
of the first electrode is above a first predetermined impedance
threshold (step (f)).
[0010] The first and second electrodes may be adjacent one
another.
[0011] The electrical sensor or stimulator may comprise one or more
of a wearable headset, an electrode patch, or an electrode lead
advanceable through the tissue, a body cavity, or a body lumen. The
wearable sensor may comprise a wearable headset.
[0012] The plurality of electrodes may comprise a first set of
electrodes on one side of the electrical sensor or stimulator and a
second set of electrodes on a second side of the electrical sensor
or stimulator opposite the first side. The electrical sensor or
stimulator may comprise a wearable headset comprising a first
hemisphere and a second hemisphere. The plurality of electrodes may
comprise a first set of electrodes on the first hemisphere and a
second set of electrodes on the second hemisphere.
[0013] The tissue of the subject may comprise a skin of the
subject, muscle tissue of the subject, or neural tissue of the
subject. The tissue of the subject comprises a skin of the subject.
The skin of the subject may comprise a scalp of the subject.
[0014] The test signal may have a predetermined frequency, and the
impedance may be determined in response to the predetermined
frequency. The predetermined frequency may be in a range of 1 to
150 Hz. The test signal may be provided through the first electrode
with a first predetermined current.
[0015] To determine the at least one voltage difference, a first
voltage difference between the first electrode and the second
electrode may be determined and a second voltage difference between
the first electrode and a third electrode may be determined. To
determine the impedance, a first impedance between the first
electrode and the second electrode may be determined in response to
the first voltage difference, a second impedance between the first
electrode and the third electrode in response to the second voltage
difference may be determined, a lesser of the first and second
impedances may be determined, and the lesser of the first and
second impedances may be assigned as the determined impedance of
the first electrode.
[0016] The predetermined acceptable impedance threshold may be in a
range of 0 to 100 k.OMEGA..
[0017] Steps (c) to (e) may be repeated for at least one additional
electrode of the plurality of electrodes to determine a plurality
of impedances for the plurality of electrodes.
[0018] The one or more of the subject or the user may be notified
by providing one or more of an audio or visual signal or alarm.
[0019] An electrical stimulation signal may further be provided
with the electrical sensor or stimulator. The electrical
stimulation signal may provide stimulation of one or more of a
nerve, a spinal cord nerve, a peripheral nerve, a skeletal muscle,
a smooth muscle, or cardiac tissue.
[0020] A bioelectrical signal may be measured from the subject as
the impedance of the first electrode is determined. The
bioelectrical signal may comprise one or more of an EEG signal, an
ENG signal, an ECG signal, an EKG signal, or an EMG signal. The
bioelectrical signal may further be recorded to generate a signal
recording, and the signal recoding pay be provided with connection
quality data points in response to the determined impedance.
[0021] The plurality of electrodes may be coupled to a processor,
and the processor may be configured to one or more of generate the
test signal, determine the at least one voltage difference, or
determine the impedance of the first electrode.
[0022] Aspects of the present disclosure provide apparatuses for
one or more of measuring a bioelectrical signal from a subject or
providing an electrical stimulation signal to the subject. An
exemplary apparatus may comprise a plurality of electrodes
configured to contact tissue of a subject and a processor coupled
to the plurality of electrodes and configured to: (i) provide a
test signal to the tissue of the subject through a first electrode
of the plurality of electrodes, (ii) determine at least one voltage
difference between the first electrode and a second electrode in
response to the test signal, (iii) determine an impedance of the
first electrode in response to the determined at least one voltage
difference, and (iv) notify 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 first
predetermined impedance threshold.
[0023] The first and second electrodes may be adjacent one
another.
[0024] The apparatus may further comprise one or more of a wearable
headset coupled to the plurality of electrodes, an electrode patch
coupled to one or more electrodes of the plurality of electrodes,
or an electrode lead coupled to one or more electrodes of the
plurality of electrodes and advanceable through the tissue, a body
cavity, or a body lumen.
[0025] The apparatus may further comprise a wearable base coupled
to the plurality of electrodes. The plurality of electrodes may
comprise a first set of electrodes on one side of the wearable base
and a second set of electrodes on a second side of the wearable
base opposite the first side. The wearable base may comprise a
wearable headset comprising a first hemisphere and a second
hemisphere, and the plurality of electrodes may comprise a first
set of electrodes on the first hemisphere and a second set of
electrodes on the second hemisphere.
[0026] The test signal may have a predetermined frequency, and the
impedance may be determined in response to the predetermined
frequency. The predetermined frequency may be in a range of 1 to
150 Hz. The test signal may be provided through the first electrode
with a first predetermined current.
[0027] To determine the at least one voltage difference, a first
voltage difference between the first electrode and the second
electrode may be determined and a second voltage difference between
the first electrode and a third electrode may be determined. To
determine the impedance, a first impedance between the first
electrode and the second electrode may be determined in response to
the first voltage difference, a second impedance between the first
electrode and the third electrode in response to the second voltage
difference may be determined, a lesser of the first and second
impedances may be determined, and the lesser of the first and
second impedances may be assigned as the determined impedance of
the first electrode.
[0028] The predetermined acceptable impedance threshold may be in a
range of 0 to 100 k.OMEGA..
[0029] The processor may be configured to repeat steps (i) to (iii)
for at least one additional electrode of the plurality of
electrodes to determine a plurality of impedances for the plurality
of electrodes.
[0030] The processor may be configured to generate a notification
to the one or more of the subject or the user by providing one or
more of an audio or visual signal or alarm.
[0031] The plurality of electrodes may be configured to measure a
bioelectrical signal from the subject as the impedance of the first
electrode is determined. The bioelectrical signal may comprise one
or more of an EEG signal, an ENG signal, an ECG signal, an EKG
signal, or an EMG signal.
[0032] The processor may be configured to record the bioelectrical
signal to generate a signal recording and provide the signal
recoding with connection quality data points in response to the
determined impedance.
[0033] The processor may be configured to direct the plurality of
electrodes to provide an electrical stimulation signal with one or
more electrodes of the plurality of electrodes. The electrical
stimulation signal may be configured to provide stimulation of one
or more of a nerve, a spinal cord nerve, a peripheral nerve, a
skeletal muscle, a smooth muscle, or cardiac tissue.
[0034] The processor may be configured to direct the plurality of
electrodes to provide the electrical stimulation signal after a
plurality of impedances for the plurality of electrodes has been
determined to assess connection quality between the plurality of
electrodes and the tissue of the subject.
[0035] Aspects of the present disclosure also provide methods of
providing an electrode connection quality assessment to a user. An
impedance measurement of an electrode coupled to a subject may be
scaled to be within a predetermined value range (step (a)). The
scaled impedance measurement may be sorted into a selected
qualitative connection quality category of a plurality of
qualitative connection quality categories (step (b)). One or more
of the scaled impedance measurement or the selected qualitative
connection quality category for the electrode coupled to the
subject may be visually displayed (step (c)).
[0036] The impedance measurement of the electrode may be
nonlinearly scaled to within the predetermined value range.
[0037] The plurality of qualitative connection quality categories
may comprise a good connection quality category, a marginal
connection quality category, and a poor connection quality
category.
[0038] The selected qualitative connection quality may be visually
displayed by a color or pattern correlated to the selected
qualitative connection quality.
[0039] The electrode coupled to the subject may comprise an EEG
electrode, an ENG electrode, an ECG electrode, an EKG electrode, or
an EMG electrode.
[0040] The steps (a) to (c) may be repeated for a plurality of
electrodes coupled to the subject.
[0041] The method may further comprise steps of (d) measuring a
bioelectrical signal with the electrode coupled to the subject, (e)
storing the measured bioelectrical signal for subsequent analysis,
and (f) tagging a region of the stored bioelectrical signal with
one or more of the impedance measurement or the selected
qualitative connection quality category at the time of
measurement.
INCORPORATION BY REFERENCE
[0042] All publications, patents, and patent applications mentioned
in this specification are herein incorporated by reference to the
same extent as if each individual publication, patent, or patent
application was specifically and individually indicated to be
incorporated by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] The novel features of the present disclosure are set forth
with particularity in the appended claims. A better understanding
of the features and advantages of the present disclosure will be
obtained by reference to the following detailed description that
sets forth illustrative embodiments, in which the principles of the
present disclosure are utilized, and the accompanying drawings of
which:
[0044] FIG. 1A illustrates a side view of a patient with an
electrode carrier system configured as a headband for EEG, in
accordance with some embodiments.
[0045] FIG. 1B illustrates a view of an electrode system for ECG on
a patient chest, in accordance with some embodiments.
[0046] FIG. 1C illustrates a view of an electrode system for EMG on
a muscle group of a patient's leg, in accordance with some
embodiments.
[0047] FIG. 1D illustrates a view of an electrode system for
stimulation to a patient's spine, in accordance with some
embodiments.
[0048] FIG. 1E illustrates a view of an electrode system for
stimulation on a muscle group of a patient arm, accordance with
some embodiments.
[0049] FIG. 2 is a schematic diagram illustrating a body interface
system for acquiring and processing signals from a living subject,
in accordance with some embodiments.
[0050] FIG. 3A is a block diagram illustrating a digital processor
used for processing signals representing bodily functions, in
accordance with some embodiments.
[0051] FIG. 3B is a schematic diagram of circuitry in a portable,
pocket-sized handheld device for sonifying electrical signals, in
accordance with some embodiments of the invention.
[0052] FIG. 4 is an illustration of a wearable device for sonifying
electrical signals obtained from a subject, in accordance with some
embodiments of the invention.
[0053] FIG. 5 is a schematic of front-end electrode connections for
a signal processor that can be used to assess electrode connection
quality, in accordance with some embodiments of the invention.
[0054] FIG. 6 is a flow chart showing a method of assessing
connection quality between the electrodes of a wearable device for
measuring electrical signals from the subject and/or providing
electrical signals to the subject, in accordance with some
embodiments of the invention.
[0055] FIG. 7A shows an exemplary user interface displaying
connection quality of various electrodes, in accordance with
embodiments of the invention.
[0056] FIG. 7B is a flow chart showing a method of correlating
impedance measurements with connection quality assessments for
display to a user, in accordance with embodiments of the
invention.
[0057] FIG. 8 shows an exemplary user interface displaying
bioelectrical signal readings including one or more tags to
indicate electrode connection quality at the time of the
measurement of the bioelectrical signal, in accordance with
embodiments of the invention.
DETAILED DESCRIPTION
[0058] The present disclosure relates to systems, devices, and
methods for calibrating the connection between the electrode(s) of
such measurement and/or stimulation devices and the tissue of the
living subject, typically skin. Aspects of the present disclosure
include methods and mechanisms for assessing electrode connection
quality that may be applicable for bioelectrical signal measurement
such as EEG, ECG, and EMG as well for providing electrical
stimulation signals to the heart, nerves, muscles, skin, and other
tissue. Many embodiments herein for assessing electrode connection
quality are described with reference to EEG measurement, but are
applicable to other bioelectrical measurement and
electro-stimulation modalities. EEG and ECG signals are typically
visually displayed to a medical professional or analytical
algorithm for diagnostic or scientific purposes.
[0059] In many embodiments, the measured bioelectrical signal may
be sonified or converted to audio form. When represented in visual
or graphical form, subtle features and attributes--and subtle
changes in features and attributes--of the electrical signals may
not always be easily discernible. However, when sonified or
converted to auditory form, these subtle features and attributes
can become more apparent to a medical professional. Furthermore,
sonification methodologies that transform the signals acquired from
the living subject into vocal patterns and vocal parameters--and
changes in vocal patterns and vocal parameters--that resemble a
human voice cam make it easier to discern, upon auditory
inspection, subtleties in the underlying electrical signals that
correspond to bodily function. Many embodiments herein may further
include the sonification of measured bioelectrical signals, in
addition to assessing electrode quality. In particular, in some
embodiments, the method can transform signals acquired from the
living subject into vocal patterns and vocal parameters that can be
used for applications in entertainment as well as user interfaces
for electronic devices. Such methods are described further in U.S.
patent application Ser. No. 13/905,377 (filed 30 May 2013), Ser.
No. 14/557,240 (filed 1 Dec. 2014), Ser. No. 15/159,759 (filed 19
May 2016), Ser. No. 15/387,381 (filed 21 Dec. 2016), and Ser. No.
15/783,346 (filed 13 Oct. 2017), the contents of which are
incorporated herein by reference.
[0060] Reference will now be made in detail to various embodiments,
examples of which are illustrated in the accompanying drawings. In
the following detailed description, numerous specific details are
set forth in order to provide a thorough understanding of the
invention and the described embodiments. However, the invention is
optionally practiced without these specific details. In other
instances, well-known methods, procedures, components, and circuits
have not been described in detail so as not to unnecessarily
obscure aspects of the embodiments.
[0061] It will be understood that, although the terms "first,"
"second," etc. are optionally used herein to describe various
elements, these elements should not be limited by these terms.
These terms are only used to distinguish one element from another.
For example, a first sensor could be termed a second sensor, and,
similarly, a second sensor could be termed a first sensor, without
changing the meaning of the description, so long as all occurrences
of the "first sensor" are renamed consistently and all occurrences
of the second sensor are renamed consistently. The first sensor and
the second sensor are both sensors, but they are not the same
sensor.
[0062] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the claims. As used in the description of the embodiments and the
appended claims, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise. It will also be understood that the
term "and/or" as used herein refers to and encompasses any and all
possible combinations of one or more of the associated listed
items. It will be further understood that the terms "comprises"
and/or "comprising," when used in this specification, specify the
presence of stated features, integers, steps, operations, elements,
and/or components, but do not preclude the presence or addition of
one or more other features, integers, steps, operations, elements,
components, and/or groups thereof.
[0063] As used herein, the term "if" is optionally construed to
mean "when" or "upon" or "in response to determining" or "in
accordance with a determination" or "in response to detecting,"
that a stated condition precedent is true, depending on the
context. Similarly, the phrase "if it is determined [that a stated
condition precedent is true]" or "if [a stated condition precedent
is true]" or "when [a stated condition precedent is true]" is
optionally construed to mean "upon determining" or "in response to
determining" or "in accordance with a determination" or "upon
detecting" or "in response to detecting" that the stated condition
precedent is true, depending on the context.
[0064] For ease of explanation, the figures and corresponding
description below are described below with reference to
sonification of signals representing brain activity (e.g.,
electroencephalography (EEG) signals) and/or heart activity (e.g.,
electrocardiography (ECG) signals) of a living subject. However,
one of skill in the art will recognize that signals representing
other bodily functions (e.g., an electromyography (EMG) signal, or
an electronystagmography (ENG) signal, a pulse oximetry signal, a
capnography signal, and/or a photoplethysmography signal) may be
substituted, or used in addition to (e.g., in conjunction with),
one or more signals representing brain activity and/or heart
activity.
[0065] Referring to FIG. 1A, an exemplary electrode carrier system
100 for measuring bioelectrical signals may generally comprise a
backing 112 shown in the side view of FIG. 1A which illustrates the
carrier system 100 secured around the head H of patient P. The
backing 112 is shown configured as a headband in this variation
although the carrier system 100 may be incorporated into any number
of other platforms or positioning mechanisms for maintaining the
electrodes against the patient body. The backing 112 is shown
configured as a headband in this variation, and the individual
electrode assemblies 114 may be spaced apart from one another so
that, when the headband is positioned upon the patient's head H,
the electrode assemblies 114 may be aligned optimally upon the head
H for receiving EEG signals. The electrode carrier system 100 may
have each of the electrodes assemblies 114 electrically coupled via
corresponding conductive wires 116 extending from the backing 112
and coupled, e.g., to a controller and/or output device 118.
Although in other variations, the electrodes assemblies 114 may be
coupled to the controller and/or output device 118 wirelessly.
[0066] The controller and/or output device 118 may generally
comprise any number of devices for receiving the electrical signals
such as electrophysiological monitoring devices and may also be
used in combination with any number of brain imaging devices, e.g.,
fMRI, PET, NIRS, etc. In one particular variation, the electrode
embodiments described herein may be used in combination with
devices such as those which are configured to receive electrical
signals from the electrodes and process them.
[0067] The electrodes assemblies 114, as described herein, may be
positioned upon the backing 112 to quickly enable conductive
contact with the underlying skin while allowing for patient comfort
such as when the patient P is reclined, as shown, with the back or
side of their head H resting upon a surface without discomfort from
the electrodes 114.
[0068] One challenge in ensuring that the individual electrodes 114
make sufficient contact with the underlying skin is the presence of
hair HR on the scalp S of the patient P. In many current EEG
devices, the region where the electrodes assemblies 114 are placed
upon the scalp S is typically shaved to remove excess hair (if
present) which interferes and inhibits electrical contact between
the electrode assemblies 114 and the scalp surface. By contrast,
the electrode carrier assemblies of the electrode carrier system
100 enable rapid reliable electrical contact on individual
electrode assemblies through the hair HR and with scalp surface
without having to remove the hair. Nevertheless, while reliable
electrical contact without removing hair may be provided, systems
and methods to quantify and or otherwise assess electrode
connection quality may still be desired. The systems, devices, and
methods to provide the aforementioned rapid and reliable electrode
contact are described in U.S. patent application Ser. No.
15/387,381 (filed 21 Dec. 2016) and Ser. No. 15/783,346 (filed 13
Oct. 2017), which are incorporated herein by reference.
[0069] While an EEG system is described above, many embodiments
herein for assessing electrode connection quality are also
applicable to other bioelectrical measurement and
electro-stimulation modalities. FIG. 1B illustrates a view of an
electrode system 120 for ECG on a chest CH of the patient P, in
accordance with some embodiments. The chest CH is shown with a view
of the heart HT and ribs RI in order to show an exemplary placement
of the electrode system 120 on the patient skin over the anatomy.
The electrode system 120 may comprise a carrier system incorporated
into a platform or positioning mechanism, such as a carrier system
integrated into a shirt. Additionally or alternatively, each of the
individual electrode assemblies 124 may be attached individually to
the skin S of the patient. Each of the individual electrode
assemblies 124 may be spaced by a skilled operator (e.g., a medical
professional) or within the positioning mechanism such that they
are aligned optimally on the patient chest to measure ECG signals.
As shown in FIG. 1B, individual electrode assemblies 124 may be
placed at approximately the six standard locations for the
precordial leads in an ECG; however, individual electrode
assemblies may be placed on the patient in any locations
appropriate to receive ECG signals. Individual electrode assemblies
may additionally or alternatively be placed on the limbs of the
patient P, for example. The system 120 may have each of the
electrode assemblies 124 electrically coupled via corresponding
conductive wires 126 to a controller and/or output device 128.
Although in other variations, the electrode assemblies 124 may be
coupled to the controller and/or output device 128 wirelessly.
[0070] The controller and/or output device 128 may generally
comprise any number of devices for receiving the electrical signals
such as electrophysiological monitoring devices and may also be
used in combination with any number of cardiovascular imaging
devices, e.g., cardiac MRI, echocardiography, coronary computed
tomography angiography, etc. In some embodiments, the electrode
assemblies 124 may be used in combination with devices such as
those which are configured to receive and process electrical
signals, such as with various filters or feature identification
algorithms.
[0071] FIG. 1C illustrates a view of an electrode system 130 for
EMG on a muscle group MG1 of a leg LG of the patient P, in
accordance with some embodiments. The electrode system 130 may
comprise a carrier system incorporated into a platform or
positioning mechanism, such as a carrier system integrated into a
sock or leg band. Additionally or alternatively, each of the
individual electrode assemblies 134 may be attached individually to
the skin S of the leg LG. In other cases, each of the individual
electrode assemblies may be placed intramuscularly, such as with
monopolar needle electrode(s). Each of the individual electrode
assemblies 134 may be spaced by a skilled operator (e.g., a medical
professional) or within the positioning mechanism such that they
are aligned optimally on the patient leg to receive the desired EMG
signals. The system 130 may have each of the electrode assemblies
134 electrically coupled via corresponding conductive wires 136 to
a controller and/or output device 138. Although in other
variations, the electrode assemblies 134 may be coupled to the
controller and/or output device 138 wirelessly.
[0072] The controller and/or output device 138 may generally
comprise any number of devices for receiving the electrical signals
such as electrophysiological monitoring devices and may also be
used in combination with any number of musculoskeletal imaging
devices, e.g., MRI, ultrasound imaging, etc. In some embodiments,
the electrode assemblies 134 may be used in combination with
devices such as those which are configured to receive and process
electrical signals, such as with various filters or feature
identification algorithms.
[0073] FIG. 1D illustrates a view of an electrode system 140 for
stimulation on a spine SP of a patient P, in accordance with some
embodiments. The back of the patient P is shown with an internal
view of the patient spinal vertebrae and major nerves in order to
show an exemplary placement of the electrode system 140 on the skin
S of the patient P, such as used during transcutaneous electrical
nerve stimulation. The electrode system 140 may comprise a carrier
system incorporated into a platform or positioning mechanism, such
as a carrier system integrated into a shirt. Additionally or
alternatively, each of the individual electrode assemblies 144 may
be attached individually to the skin S of the patient P's back.
Each of the individual electrode assemblies 144 may be spaced by a
skilled operator (e.g., a medical professional) or within the
positioning mechanism such that they are aligned optimally on the
patient P's back to output signals to stimulate the spine SP. In
other cases, the individual electrode assemblies 144 are implanted
subcutaneously, such as a variation on a "pain pacemaker" as known
in the art. The system 140 may have each of the electrode
assemblies 144 electrically coupled via corresponding conductive
wires 146 to a controller and/or output device 148. Although in
other variations, the electrode assemblies 144 may be coupled to
the controller and/or output device 148 wirelessly.
[0074] The controller and/or output device 148 may generally
comprise any number of devices for outputting the electrical
signals such as electrophysiological stimulation devices and may
also be used in combination with any number of cerebrospinal
imaging devices, e.g., MM, spinal computed tomographic imaging,
etc. In some embodiments, the electrode assemblies 144 may be used
in combination with devices such as those which are configured to
receive and process electrical signals, such as with various
filters or feature identification algorithms.
[0075] FIG. 1E illustrates a view of an electrode system 150 for
stimulation on a muscle group MG2 of an arm A of the patient P,
accordance with some embodiments. The electrode system 150 may
comprise a carrier system incorporated into a platform or
positioning mechanism, such as a carrier system integrated into a
glove or a sleeve. Additionally or alternatively, each of the
individual electrode assemblies 154 may be attached individually to
the skin S of the arm A. Each of the individual electrode
assemblies 154 may be spaced by a skilled operator (e.g., a medical
professional) or within the positioning mechanism such that they
are aligned optimally on the arm A to output signals to stimulate
the muscle group MG2 in the arm A. The system 150 may have each of
the electrode assemblies 154 electrically coupled via corresponding
conductive wires 156 to a controller and/or output device 158.
Although in other variations, the electrode assemblies 154 may be
coupled to the controller and/or output device 158 wirelessly.
[0076] The controller and/or output device 158 may generally
comprise any number of devices for outputting the electrical
signals such as electrophysiological stimulation devices and may
also be used in combination with any number of musculoskeletal
imaging devices, e.g., MRI, ultrasound imaging, etc. In some
embodiments, the electrode assemblies 154 may be used in
combination with devices such as those which are configured to
receive and process electrical signals, such as with various
filters or feature identification algorithms.
[0077] The bioelectrical measurement and/or stimulation systems
described herein may include consoles, controllers, or other
processing units to acquire, record, measure, process, and/or
generate bioelectrical and/or stimulation signals. FIG. 2
illustrates body interface system 200 for sensing, acquiring and
processing one or more signals obtained from a living subject
(e.g., obtained from a human or animal's brain with the electrode
carrier system 100 and similar electrode systems illustrated in
FIG. 1B-1E) to produce a representation of an acoustic signal (also
referred to herein as an "output acoustic signal") corresponding to
the one or more signals (e.g., representing brain activity). In
some circumstances, body interface system 200 is employed in a
clinical setting (e.g., during or before surgical interventions
and/or during diagnosis and/or treatment of conditions, such as
epileptic seizures) for aural (e.g., auditory) measurement of
monitoring of brain activity. Alternatively, or in addition, body
interface system 200 is deployed as part of a user interface for a
handheld or wearable device (e.g., a smart-phone, tablet, or the
like) for diagnostic, entertainment, biofeedback, monitoring,
therapeutic or other purposes. In some embodiments, one or more
components of body interface system 200 constitute a handheld or
wearable device for sonifying electrical signals obtained from a
subject, such as the head-worn electrical carrier system 100 and
similar electrode systems illustrated in FIG. 1B-1E. Another
example of such a wearable device for sonifying electrical signals
obtained from a subject is shown in FIG. 4. In some implementations
of the wearable device 400, shown in FIG. 4, digital processor
system 260 is embedded in the wearable device, for example, in a
"headband housing" that also holds dry or wet electrodes that
contact both sides (left and right sides) of the subject's head. In
some other implementations, the digital processor system 260 is not
embedded in a headband housing, and is instead coupled to
electrodes in (or held in position by) a headband by one or more
electrical wires or connectors. Optionally, digital processor
system 260 has a separate housing that includes a clip for
attachment to the headband.
[0078] In some embodiments, as shown FIG. 2, the body interface
system 200 includes one or more sensors 210 (e.g., sensor 210-1 and
sensor 210-2), optionally includes one or more analog front ends
220 (e.g., one or more analog front end modules) and a digital
processor system 260 (herein often called digital processor 260 for
ease of reference) for receiving and processing signals from
sensors 210. In some embodiments, digital processor system 260
includes the one or more analog front ends.
[0079] In some embodiments, sensors 210 are provided to interface
with a living subject's brain to obtain e.g., sense and/or acquire)
sensor time-domain signals corresponding to brain electrical
activity. In some embodiments, sensors 210 are a component of a
handheld device for sonifying electrical signals (such as the
head-worn electrical carrier system 100 in FIG. 1, similar
electrode systems illustrated in FIG. 1B-1E, and the wearable
device 400 in FIG. 4). Alternatively, in some embodiments, the
wearable device is configured to interface with the sensors 210
(e.g., the sensors 210 are disposable and plug into the wearable
device). In some embodiments, the sensors 210 include one or more
electrodes.
[0080] As an example, signals corresponding to brain electrical
activity are obtained from a human brain and correspond to
electrical signals obtained from a single neuron or from a
plurality of neurons. In some embodiments, the one or more
electrical signals represent electroencephalography (EEG) data that
are concordant with laboratory EEG data. In some embodiments,
sensors 210 include one or more sensors affixed (e.g., taped,
attached, glued) externally to a human scalp (e.g., extra-cranial
sensor 210-1). For example, extra-cranial sensor 210-1 may include
an electrode (e.g., electroencephalography (EEG) electrode) or a
plurality of electrodes (e.g., electroencephalography (EEG)
electrodes) affixed externally to the scalp (e.g., glued to the
skin via conductive gel), or more generally positioned at
respective positions external to the scalp. Alternatively, dry
electrodes can be used in some implementations (e.g., conductive
sensors that are mechanically placed against a living subject's
body rather than planted within the living subject's body or held
in place with a conductive gel). An example of a dry-electrode is a
headband with one or more metallic sensors (e.g., electrodes) that
is worn by the living subject during use (FIG. 4). The signals
obtained from an extra-cranial sensor 210-1 are sometimes herein
called EEG signals or time-domain EEG signals.
[0081] In some embodiments, although not shown in FIG. 2, sensors
210 are heartbeat pulse sensors. In some embodiments, sensors 510
can be used both as EEG sensors (e.g., by placing sensors 210 on
the subject's head) and as heartbeat pulse sensors (e.g., by
placing sensors 210 on the subject's chest or another location
where a heart signal is detectable). The heartbeat pulse sensors
are provided to interface with a living subject's heart to obtain
(e.g., sense and/or acquire) sensor time-domain signals
corresponding to heart electrical activity. For example, signals
corresponding to heart electrical activity may be obtained from a
human heart and correspond to electrical signals obtained from a
single cardiomyocyte or from a plurality of cardiomyocytes (e.g., a
sinoatrial (SA) node of a human subject). In some embodiments, the
heartbeat pulse sensors include one or more sensing elements
affixed (e.g., taped, attached, glued) externally to a human body
(e.g., a human subject's chest, abdomen, arm, or leg). For example,
the heartbeat pulse sensors may include an electrode (e.g.,
electrocardiography (ECG) electrode) or a plurality of electrodes
(e.g., electrocardiography ECG) electrodes) affixed externally to
the human body (e.g., glued to the skin via conductive gel), or
more generally positioned at respective positions external to the
human body. Alternatively, dry electrodes can be used in some
implementation (e.g., conductive sensors that are mechanically
placed against a human body rather than being implanted within the
human body or held in place with a conductive gel). An example of a
dry-electrode is a chest strap with one or more metallic sensors
(e.g., electrodes) that is worn by the living subject during use.
Another example of a dry-electrode is a thumb apparatus or a hand
apparatus with one or more metallic sensing elements (e.g.,
electrodes) that is touched (e.g., with the living subject's
thumbs) and/or held onto (e.g., with the living subject's hands) by
the living subject during use. The signals obtained from heartbeat
pulse sensors are sometimes herein called ECG signals or
time-domain ECG signals.
[0082] In some embodiments, heartbeat pulse sensors sense voltages
corresponding to heart electrical activity. In alternative
embodiments, heartbeat pulse sensors sense electrical currents
corresponding to heart electrical activity. In some
implementations, heartbeat pulse sensors sense differential
voltages (e.g., differences in voltage values) between two
measurement locations (e.g., between two sensing elements). For
example, when a respective heartbeat pulse sensor includes two or
more sensing elements (e.g., electrodes) positioned at respective
positions external to the human body, the respective heartbeat
pulse sensor may sense differential voltages (e.g., bipolar
voltages) between the two or more sensing elements located at the
respective positions. In some implementations, a "twelve-lead
electrocardiogram" is constructed by referencing each sensing
element of a set of sensing elements to one or more other sensing
elements to produce a corresponding set of differential voltage
signals (e.g., a twelve-lead set of differential voltage signals),
each of which is a respective sensor time-domain signal.
[0083] In some embodiments, although not shown in FIG. 2, sensors
210 are sensors of electrical potential produced by skeletal
muscles. In some embodiments, sensors 210 can be used both as EEG
sensors and as EMG sensors (e.g. by placing sensors 210 on the
patient's skin near a skeletal muscle group). The electrical
potential sensors are provided to interface with a living subject's
muscles to obtain (e.g. sense and/or acquire) sensor time-domain
signals corresponding to muscle electrical activity. For example,
signals corresponding to muscle electrical activity may be obtained
from a human quadriceps and correspond to electrical signals
obtained from contraction of said quadriceps. In some embodiments,
the electrical potential sensors may include an electrode or a
plurality of electrodes affixed externally to the human body (e.g.
glue to the skin via conductive gel), or more generally positioned
at respective positions external to the human body. Alternatively,
dry electrodes can be used in some implementations (e.g.,
conductive sensors that are mechanically placed against a human
body rather than being implanted within the human body or held in
place with a conductive gel). Alternatively, electrodes may be
implanted in the patient (e.g. into the quadriceps), such as in
intramuscular EMG. The signals obtained from the electrical
potential sensors are sometimes herein called EMG signals or
time-domain EMG signals.
[0084] In some embodiments, EMG sensors sense voltages
corresponding to muscular electrical activity. In alternative
embodiments, EMG sensors sense electrical currents corresponding to
muscular electrical activity. In some implementations, EMG sensors
sense differential voltages (e.g., differences in voltage values)
between two measurement locations (e.g., between two sensing
elements). For example, when a respective EMG sensor includes two
or more sensing elements (e.g., electrodes) positioned at
respective positions external to the human body, the respective EMG
sensor may sense differential voltages (e.g., bipolar voltages)
between the two or more sensing elements located at the respective
positions.
[0085] In some embodiments, arrays of sensors (e.g., sensors 210)
are designed to record intracranial EEG and produce a plurality of
sensor time-domain signals. In some embodiments, sensor time-domain
signals include wideband features including high-gamma bursts in
the range of 80-150 Hz. In some embodiments, sensor time-domain
signals include frequencies (sometimes called frequency components)
below (e.g., lower than or in the lowest ranges of) the human
audible frequency-range.
[0086] In some implementations, analog front end 220 receives
sensor time-domain signals from sensors 210 and optionally
pre-processes the senor time-domain signals to produce filtered
sensor time-domain signals. In some embodiments, a separate (e.g.,
independent) analog front end is provided for interfacing with each
of a set of sensors 210. In some embodiments, a first analog front
end is provided for interfacing with a set of EEG sensors 210. A
second (i.e., distinct) electrocardiography (ECG) analog front end
is provided for interfacing with a set of heartbeat pulse sensors
210. A third (i.e., distinct) electromyography (EMG) analog front
end is provide for interfacing with a set of sensors for the
electric potential produced by skeletal muscles. In such
embodiments, body interface system 200 comprises a plurality of
analog front end modules (e.g., analog front end 220-a, analog
front end 220-b, though analog front end 220-n) for interfacing
with a plurality of sensors 210.
[0087] In some embodiments, although not shown in FIG. 2, sensors
210 output electrical signals to stimulate a patient nerve. In some
embodiments, sensors 210 can be used both as EEG sensors and
electrical nerve stimulators (e.g. by placing sensors 210 on a
subject spine or another location where a patient nerve can be
stimulated). The electrical nerve stimulators are provided to
interface with a living subject's nerves (e.g., spinal cord) to
output time-domain signals corresponding to electrical signals to
stimulate a patient's nerves. For example, electrical signals may
mask patient pain in order to treat chronic regional pain. In some
embodiments, the nerve stimulators include one or more stimulating
elements affixed (e.g., taped, attached, glued) externally to a
human body (e.g., a human subject's chest, abdomen, arm, or leg).
For example, the nerve stimulators may include an electrode or a
plurality of electrodes affixed externally to the human body (e.g.,
glued to the skin via conductive gel), or more generally positioned
at respective positions external to the human body. Alternatively,
dry electrodes can be used in some implementation (e.g., conductive
sensors that are mechanically placed against a human body rather
than being implanted within the human body or held in place with a
conductive gel). In other embodiments, the nerve stimulators
include one or more stimulating elements implanted subcutaneously
(e.g., in proximity to a patient spinal cord), such as in a Dorsal
Column Stimulator.
[0088] In some embodiments, nerve stimulators output voltages to
effect nerve electrical activity. In alternative embodiments, nerve
stimulators output electrical currents to effect nerve electrical
activity. In some implementations, nerve stimulators output
multiple voltages on different electrodes in order to produce
differential voltages (e.g., differences in voltage values) between
two stimulation locations (e.g., between two stimulation elements).
For example, when a respective nerve stimulator includes two or
more stimulating elements (e.g., electrodes) positioned at
respective positions external to the human body, the respective
nerve stimulator may apply differential voltages (e.g., bipolar
voltages) between the two or more stimulating elements located at
the respective positions. The signals output from the nerve
stimulators are sometimes herein called nerve stimulation signals
or time-domain nerve stimulation signals.
[0089] In some embodiments, although not shown in FIG. 2, sensors
210 output electrical signals to stimulate a patient skeletal
muscle. In some embodiments, sensors 210 can be use both as EMG
sensors and electrical muscle stimulators (e.g. by placing sensors
210 on a subject leg or another location where a patient muscle can
be stimulated). The electrical muscle stimulators are provided to
interface with a living subject's musculature (e.g., a quadriceps)
to output time-domain signals corresponding to electrical signals
to stimulate a patient's muscles. For example, electrical signals
may induce muscular contraction, for example, to prevent atrophy,
to re-educate a muscle, to increase range of motion, etc. or to
relax patient muscle spasms. In some embodiments, the muscle
stimulators include one or more stimulating elements affixed (e.g.,
taped, attached, glued) externally to a human body (e.g., a human
subject's chest, abdomen, arm, or leg). For example, the muscle
stimulators may include an electrode or a plurality of electrodes
affixed externally to the human body (e.g., glued to the skin via
conductive gel), or more generally positioned at respective
positions external to the human body. Alternatively, dry electrodes
can be used in some implementations (e.g., conductive sensors that
are mechanically placed against a human body rather than being
implanted within the human body or held in place with a conductive
gel). In other embodiments, the muscle stimulators include one or
more stimulating elements implanted subcutaneously (e.g., in
proximity to a patient quadriceps.
[0090] In some embodiments, muscle stimulators output voltages to
effect muscular electrical activity. In alternative embodiments,
muscle stimulators output electrical currents to effect muscular
electrical activity. In some implementations, muscle stimulators
output multiple voltages on different electrodes in order to
produce differential voltages (e.g., differences in voltage values)
between two stimulation locations (e.g., between two stimulation
elements). For example, when a respective muscle stimulator
includes two or more stimulating elements (e.g., electrodes)
positioned at respective positions external to the human body, the
respective nerve stimulator may apply differential voltages (e.g.,
bipolar voltages) between the two or more stimulating elements
located at the respective positions. The signals output from the
muscle stimulators are sometimes herein called muscle stimulation
signals or time-domain muscle stimulation signals.
[0091] In some implementations, analog front end 220 outputs
time-domain signals from sensors or stimulators 210 and optionally
pre-processes the time-domain signals. In some embodiments, a
separate (e.g., independent) analog front end is provided for
interfacing with each of a set of sensors or stimulators 210. In
some embodiments, a fourth analog front end is provided for
interfacing with a set of nerve stimulators 210. In some
embodiments, a fifth analog front end is provided for interfacing
with a set of muscle stimulators 210. In such embodiments, body
interface system 200 comprises a plurality of analog front end
modules (e.g., analog front end 220-a, analog front end 220-b,
though analog front end 220-n) for interfacing with a plurality of
sensors or stimulators 210.
[0092] As shown in FIG. 2, body interface system 200 may include
digital processor system 260 for processor signals obtained from
the living subject (e.g., signals corresponding to electric
activity and/or stimulation of the brain or heart or musculature),
optionally after the signals are pre-processed by analog front end
220. Digital processor 260 may include signal conditioning modules
230, signal modulators 240, and synthesizer modules 550. In some
embodiments, a separate (e.g., independent) signal conditioning
module, a separate (e.g., independent) signal modulator, and/or a
separate (e.g., independent) synthesizer module is provided for
interfacing with each sensor or stimulator 210 in a set of two or
more sensors or stimulators 210 (optionally through a separate
analog front end module). In such embodiments, body interface
system 200 comprises a plurality of signal conditioning modules 230
and/or a plurality of synthesizer modules 250 for interfacing with
a plurality of sensors or stimulators 210 and processing signals
obtained from those sensors or stimulators. In some
implementations, signal modulator(s) 240 receive(s) the digitized
time-domain signals output by signal conditioning module(s) 230,
and concurrently generate a set of acoustic parameters, including a
plurality of time-varying acoustic parameters from (e.g., using)
the digitized time-domain signals. One or more of the plurality of
time-varying acoustic parameters is modulated in accordance with at
least the signal value of the time-domain signal. In some
embodiments, a synthesizer module (e.g., synthesizer module(s) 250)
combines the concurrently generated set of acoustic parameters to
produce a representation of a time-domain signal.
[0093] In some embodiments, a plurality of representations of
acoustic signals is combined to produce a combined acoustic signal.
Alternatively, a combined acoustic signal is generated by combining
acoustic signals corresponding to the plurality of representations
of acoustic signals produced by digital processor system 260Signal
processing and sonification for the body interface system 200 is
further described in U.S. patent application Ser. No. 13/905,377
(filed 30 May 2013), Ser. No. 14/557,240 (filed 1 Dec. 2014), and
Ser. No. 15/159,759 (filed 19 May 2016), the contents of which are
incorporated herein by reference.
[0094] FIG. 3A is a block diagram illustrating digital processor
system 260 in accordance with some embodiments, and FIG. 3B depicts
an example of a set of components on a printed circuit board (PCB)
that implement digital processor system 260. Digital processor
system 260 typically includes one or more processing units (CPUs)
302 for executing modules, programs and/or instructions stored in
memory 310 and thereby performing processing operations; one or
more network or other communications interfaces 304 (e.g., a wired
communication interface such as a USB port, micro-USB port, or the
like, and/or a wireless communication interface); memory 310; and
one or more communication buses 309 for interconnecting these
components. The communication buses 309 optionally include
circuitry (sometimes called a chipset) that interconnects and
controls communications between system components. Digital
processor system 260 optionally includes a user interface 305
comprising a display 306, one or more input devices 307 (e.g., one
or more buttons, and, optionally, one or more of a microphone,
keypad, and touch screen, etc.), and one or more speakers 308
(e.g., for audio playback of acoustic signals corresponding to
brain and/or heart activity). Display 306 optionally includes one
or more LEDs, for example, one or more LEDs for indicating a status
of digital processor system 260 (e.g., a steady blinking LED to
indicate that EEG signals are being received and/or to indicate
that accelerometer signals corresponding to mechanical movement of
the subject are sufficiently low-amplitude to allow DSP 260 to
produce valid sonification of EEG signals) and, in another example,
an LED to indicate battery status (e.g., a red LED that is turned
on when battery power is low, and/or a green LED that is turned on
when an internal battery is charged and that blinks on and off in a
predefined pattern when battery power is low).
[0095] As shown in FIG. 3B, in some embodiments, input devices 307
may include a power on/off button for powering digital processor
system 260 on and off, a reset button for resetting digital
processor system 260 to a predefined initial state, and a record
button for starting and stopping recording of EEG data
corresponding to a subject's brain activity. Furthermore, in some
embodiments, input devices 307 include a microphone for receiving
and recording a user's spoken comments made just prior to, or
while, DSP 260 records EEG data corresponding to a subject's
pressing of the "record" button shown in FIG. 3B. Digital processor
system 260 may record any spoken comments by the user for a
predefined period (e.g., 5 to 10 seconds following the button
press), and also records EEG data corresponding to the subject's
brain activity or other digitized time domain data until the user
presses the record button a second time, or until a predefined
period of time elapses (e.g., 5 minutes), or until a predefined
period of time (e.g., 5 minutes) elapses during which the device
(digital processor system 260) does not receive electrical signals
corresponding to abnormal brain activity or other abnormal
electrical activity or other cue to stop collection.
[0096] Digital processor system 260 optionally includes sensor
interfaces 370 for interfacing with sensors or stimulators 210
(FIG. 2) and/or analog front end 220 (FIG. 2) and synthesizer
module 374 for combining concurrently generated acoustic parameters
to produce a representation of an acoustic signal corresponding to
one or more time-domain signals. As explained in more detail below,
in some embodiments, sensors 210 are located, at least in part,
within the same housing that holds digital processor system 260,
while in some other embodiments, sensors or stimulators 210 are
located external to that housing and are coupled to digital
processor system 260 via one or more electrical connectors and
sensor interface(s) 370.
[0097] Digital processor system 260 optionally (and typically)
includes a battery 382 (e.g., a rechargeable battery) and charger
380, to provide power to digital processor system 260 and enable
operation of digital processor system 260 without connection to an
external power source (except to charge battery 382). In some
embodiments, battery 382 is charged via charger 380, when an
external power source is connected to system 260 via a USB port or
micro-USB port of the device.
[0098] Memory 310 may include high-speed random access memory, such
as DRAM, SRAM, DDR RAM or other random access solid state memory
devices; and optionally includes non-volatile memory, such as one
or more magnetic disk storage devices, optical disk storage
devices, flash memory devices, or other non-volatile solid state
storage devices. Memory 310 optionally includes one or more storage
devices remotely located from the CPUs 302, memory 310, or
alternately the non-volatile memory devices within memory 310,
comprises a non-transitory computer readable storage medium. In
some embodiments, memory 310, or the computer readable storage
medium of memory 310 stores the following programs, modules and
data structures, or a subset thereof: [0099] Operating system 312
that may include procedures for handling various basic system
services and for performing hardware dependent tasks; [0100]
Network communication module 314 that may be used for connecting
digital processor system 260 to other computers via the one or more
communication network interfaces 309 (wired or wireless) and one or
more communication networks, such as the Internet, other wide area
networks, local area networks, metropolitan area networks, and so
on; [0101] User interface module 316 that may receive commands from
the user via one or more input devices 307 of user interface 315,
generates user interface objects in display device 306, and
optionally generates representations of signals corresponding to
brain and/or heart activity, information corresponding to sensors
and sensor interfaces, and information related to the configuration
of body interface system 300 for display on display device 306;
[0102] Optional local data storage 270 that may store data
corresponding to the one or more electrical signals (e.g., data
storage 270 stores raw EEG or other data and/or audio data so that
the data can be reviewed later by, e.g., a specialist). In some
implementations, data storage 270 includes a removable non-volatile
memory card, such as a micro SD flash memory card (see ".mu.SD" in
FIG. 3B, which represents a micro-SD card "reader" for receiving
and interfacing a micro SD flash memory card to a microcontroller).
As an alternative, or in addition to data storage 270, digital
processor system 260 may communicate with cloud-based storage
(e.g., storage that is remote from the device) to store data
corresponding to the one or more electrical signals.
[0103] Each of the above identified elements is optionally stored
in one or more of the previously mentioned memory devices of
digital processor system 260, and corresponds to a set of
instructions for programing a function described above. The above
identified modules or programs (i.e., sets of instructions) need
not be implemented as separate software programs, procedures or
modules, and thus various subsets of these modules is optionally
combined or otherwise re-arranged in various embodiments. In some
embodiments, memory 310 optionally stores a subset of the modules
and data structures identified above. Furthermore, memory 310
optionally stores additional modules and data structures not
described above. For example, in some embodiments, memory 310 may
store one or more data analysis modules 324, for analyzing EEG or
other data received by digital processor system 260 and conveying
one or more results to a user of the device (e.g., via display 306
or speaker(s) 308), or to a remote device or user via
communications interface 304. The one or more data analysis modules
324, if provided, may use any of a number of seizure or other
pathological waveform detection methods, including data analysis
methods previously developed or developed in the future.
[0104] Although FIGS. 3A-3B show digital processor system 260,
FIGS. 3A-3B are intended to provide functional descriptions of the
various features which are optionally present in a digital
processor system, and not as a structural schematic of the
embodiments described herein. In practice, and as recognized by
those of ordinary skill in the art, items shown separately could be
combined and some items could be separated. For example, some items
shown separately in FIGS. 3A-3B could be implemented on a single
digital processor system and single items could be implemented by
one or more digital processor systems. The actual number of digital
processor systems used to implement digital processor system 260
and how features are allocated among then may vary from one
implementation to another.
[0105] FIG. 4 is an illustration of a wearable device 400 for
sonifying electrical signals obtained from subject 402, in
accordance with some embodiments. In other embodiments, a wearable
device for sonifying electrical signals may have the form of a
shirt, sock, glove etc. for sonifying signals from EMG or ECG or
for sonifying signals for stimulating a patient nerve or muscle.
Device 400 may include a plurality of electrodes 452 (e.g., 452a,
452b). These electrodes can be dry or wet electrodes. Electrodes
452 may be configured to be placed at respective locations on the
subject's body. For example, in some embodiments, electrode 452a
and electrode 452b are positioned (placed) substantially at
predefined locations when subject 402 wears device 400. The
plurality of electrodes may produce one or more electrical signals
corresponding to brain activity. For example, device 400 may
include sensors 210-4 and 210-5 which produce an electrical signal
corresponding to left hemisphere brain activity, and further
includes sensors 210-6 and 210-7 which produce an electrical signal
corresponding to right hemisphere brain activity. Device 400 may
include an analog-to-digital converter (ADC) to digitize the one or
more electrical signals and a processor that receives the one or
more digitized electrical signals and produces a representation of
an acoustic signal. Device 400 may further include a speaker system
408 that sonifies the representation of the acoustic signal. In
some embodiments, the ADC, the processor, and the speaker system
are incorporated into wearable housing 404. In some embodiments,
wearable housing 404 is a headband, a helmet, a hat, a sock, a
glove, a shirt, pants, etc. In some embodiments, wearable housing
404 includes a headband that includes an adjustable strap or
housing that is configured to fully wrap around the subject's head
to stably hold the wearable housing on the subject's head. In some
embodiments, device 400 interfaces with a chest strap having one or
more electrodes to measure a heartbeat signal concurrently with the
brain signals.
[0106] Device 400 may be used in some circumstances for long-term
monitoring of rarely (e.g., sparsely or infrequently) occurring
conditions. Device 400 can be worn for prolonged periods of time
without becoming awkward or uncomfortable. In addition, device 400
can be easily removed for bathing and the like. This convenience
can allow device 400 to monitor a patient for a month or longer,
greatly increasing the likelihood that an episode will be measured
by device 400 and thus produce data of an episode that is available
for a medical professional to review. For example, in some
embodiments, device 400 is used to produce diagnostics for
neurology patients complaining of an altered mental state, such as
dizziness, lightheadedness, or vertigo. As another example, in some
circumstances, device 400 may be worn by epileptics and/or patients
with other types of diagnosed conditions to alert them of an
on-coming episode. For example, an epileptic patient may wear
device 400 while driving. Device 400 may continuously monitor the
epileptic patient for indicia of a pre-ictal state, which signifies
that the patient is likely to start seizing. When the device
detects indicia of an ictal state, the device can alert the patient
using speaker 408, stating, e.g., "Pull Over! Pull Over! Seizure
detected!"
[0107] FIG. 5 shows a schematic 500 of front-end electrode
connections for a signal processor that can be used to assess
connection quality between the electrodes 210 of the wearable
device 100 or 400 and the subject. The digital processor 260 of the
wearable device 100 or 400 may comprise an electrode impedance
check function, which can allow digital processor 260 to assess the
connection quality of the EEG electrodes to the scalp of the
patient and provide the assessment to the user and/or subject. The
digital processor system 260 may calculate complex impedance using
Ohm's Law: V=I*Z, where Vis voltage, I is current, and Z is
impedance. The impedance can therefore be calculated if the voltage
is measured at a known current: Z=V/I. In many embodiments, a
current on the order of a few nanoamps up to a few microamps (5 nA
to 25 .mu.A, for example) would work well with minimal effect on
and/or sensation felt by the subject. The analog front-end chip 510
of the digital processor 260, that is, the integrated circuit (IC)
containing the amplifiers and ADCs for the EEG readout, can allow a
known current to be injected at a particular frequency into any of
the electrodes 210.
[0108] In many embodiments, the digital processor system 260 does
not have a dedicated reference electrode to measure each electrode
against. Instead, each electrode 210-n can be referenced to its
adjacent electrode(s). Since the ADC channels on a given hemisphere
of the wearable device 100 or 400 may all be interconnected through
shared electrodes 210-n (i.e., some of the electrodes 210-n may be
connected to the inputs of two adjacent ADCs), the relationship
between the electrodes can be used to find the voltage difference,
and therefore the impedance, between any combination of two
electrodes 210-n on a hemisphere.
[0109] FIG. 5 shows analog front-end electrode connections for the
digital signal processor 260. There may be ten electrodes 210-1 to
210-10 connected to the 8-channel differential amplifier/ADC chip
510. The electrodes 210-1 to 210-10 can be divided into two sides
covering the left and right hemispheres, with 5 electrodes on each
side forming 4 differential data channels: ADC channel 501
(connected to electrodes 210-1 and 210-2), ADC channel 502
(connected to electrodes 210-2 and 210-3), ADC channel 503
(connected to electrodes 210-3 and 210-4), ADC channel 504
(connected to electrodes 210-4 and 210-5) for the left or right
side, and likewise ADC channel 505 (connected to electrodes 210-6
and 210-7), ADC channel 506 (connected to electrodes 210-7 and
210-8), ADC channel 507 (connected to electrodes 210-8 and 210-9),
and ADC channel 508 (connected to electrodes 210-9 and 210-10) for
the opposite side, for eight data channels total. Each electrode
210-1 to 210-10 may be connected to either one or two differential
amplifier inputs. The relationship between the electrodes can be
used to find the voltage difference, and therefore the impedance,
between any combination of two electrodes 210-n on a hemisphere as
follows: [0110] electrode 210-2-electrode 210-1=ADC channel 501,
electrode 210-3-electrode 210-2=ADC channel 502, and, therefore
electrode 210-3-electrode 210-1=ADC channel 502+ADC channel 501;
[0111] electrode 210-3-electrode 210-2=ADC channel 502, electrode
210-4-electrode 210-3=ADC channel 503, and, therefore electrode
210-4-electrode 210-2=ADC channel 503+ADC channel 502; [0112]
electrode 210-4-electrode 210-3=ADC channel 503, electrode
210-5-electrode 210-4=ADC channel 504, and, therefore electrode
210-5-electrode 210-3=ADC channel 504+ADC channel 503; [0113]
electrode 210-2-electrode 210-1=ADC channel 501, electrode
210-3-electrode 210-2=ADC channel 502, electrode 210-4-electrode
210-3=ADC channel 503, and, therefore electrode 210-4-electrode
210-1=ADC channel 503+ADC channel 502+ADC channel 501; [0114]
electrode 210-3-electrode 210-2=ADC channel 502, electrode
210-4-electrode 210-3=ADC channel 503, electrode 210-5-electrode
210-4=ADC channel 504, and, therefore electrode 210-5-electrode
210-2=ADC channel 504+ADC channel 503+ADC channel 502; [0115]
electrode 210-2-electrode 210-1=ADC channel 501, electrode
210-3-electrode 210-2=ADC channel 502, electrode 210-4-electrode
210-3=ADC channel 503, electrode 210-5-electrode 210-4=ADC channel
504, and, therefore electrode 210-5 [0116] electrode 210-1=ADC
channel 504+ADC channel 503+ADC channel 502+ADC channel 501; [0117]
electrode 210-7-electrode 210-6=ADC channel 506, electrode
210-8-electrode 210-7=ADC channel 506, and, therefore electrode
210-8-electrode 210-6=ADC channel 506+ADC channel 505; [0118]
electrode 210-8-electrode 210-7=ADC channel 507, electrode
210-9-electrode 210-7=ADC channel 507, and, therefore electrode
210-9-electrode 210-7=ADC channel 507+ADC channel 506; [0119]
electrode 210-9-electrode 210-8=ADC channel 508, electrode
210-10-electrode 210-8=ADC channel 508, and, therefore electrode
210-10-electrode 210-8=ADC channel 508+ADC channel 507; [0120]
electrode 210-7-electrode 210-6=ADC channel 505, electrode
210-8-electrode 210-7=ADC channel 506, electrode 210-9-electrode
210-8=ADC channel 507, and, therefore electrode 210-9-electrode
210-6=ADC channel 507+ADC channel 506+ADC channel 505; [0121]
electrode 210-8-electrode 210-7=ADC channel 506, electrode
210-9-electrode 210-8=ADC channel 507, electrode 210-10-electrode
210-9=ADC channel 508, and, therefore electrode 210-10-electrode
210-7=ADC channel 508+ADC channel 507+ADC channel 506; [0122]
electrode 210-7-electrode 210-6=ADC channel 505, electrode
210-8-electrode 210-7=ADC channel 506, electrode 210-9-electrode
210-8=ADC channel 507, electrode 210-10-electrode 210-9=ADC channel
508, and, therefore electrode 210-10-electrode 210-6=ADC channel
508+ADC channel 507+ADC channel 506+ADC channel 505;
[0123] FIG. 6 is a flow chart showing a method 600 of assessing
connection quality of the electrodes of a wearable device 100 or
400 for sonifying electrical signals that is coupled to the scalp
of the subject in a step 605. While FIG. 6 shows an exemplary
method of assessing connection quality associated with an EEG
measurement, in other embodiments, a method 600 may be used to
assess the connection quality associated with sensing or applying
another type of electrical signal, such as those disclosed herein.
Additionally or alternatively, at a step 605, the wearable device
may be coupled to a patient body in the manners disclosed herein to
sense or stimulate a patient. The number of electrodes tested may
be at the discretion of the user. A minimum of two electrodes,
without a common ground or reference electrode required, may be
assessed for connection quality. Impedance values are assigned to
the electrodes 210-n and presented to the user as an indicator for
connection quality, either through a summary of the values or each
of the impedance values themselves, for example. In many
embodiments, an impedance of less than or equal to 5 k.OMEGA. would
indicate good connection quality. In some embodiments, an impedance
of less than or equal to 100 k.OMEGA. would signify acceptable
connection quality. In some embodiments, the acceptable range of
impedances is further divided into tiered ranges, for example, a
good connection quality impedance range, a marginal connection
quality impendence range, and a bad connection quality impedance
range. In some embodiments, the upper range of the acceptable range
of the impedance values may be used as a threshold above which
connection quality is identified as poor and the user notified of
such. To assign an impedance value to any particular one of the ten
electrodes: [0124] 1) A test signal (e.g., a periodic current
output such as a sinusoidal, square, or triangle wave, etc.) may be
turned on in the particular electrode at a certain frequency (step
610); [0125] 2) Voltage samples from all ADC channels may be
collected on the hemisphere (e.g., with four channels) where the
particular electrode is located (step 615); [0126] 3) The voltage
difference between the particular electrode and all other
electrodes on that side may be calculated and the calculated value
may be stored in buffers (step 620); [0127] 4) A frequency
decomposition (e.g. FFT (Fast Fourier Transform), Goertzel
Algorithm, etc.) may be performed on each buffer once a sufficient
number of samples has been collected; the value of the resulting
frequency spectrum at the bin corresponding to the test signal
frequency allows the voltage at that frequency to be calculated and
the voltage at the particular frequency for all electrode pairs
that include the particular electrode on the same device hemisphere
or side may be determined (step 625); [0128] 5) The impedance
between the particular electrode and each other electrode on that
side may be calculated using Ohm's Law, with the voltage being
calculated for each electrode pair and the current of the test
signal being known (step 630); and [0129] 6) The minimum impedance
of all the calculated pairs may be assigned to the particular
electrode (step 635), and this value may be closest to the true
impedance of that electrode, and often the lower the impedance of
the other electrodes, the more accurate this value can become.
[0130] After repeating the above process for all 10 electrodes
(step 640), the measured impedance and/or a threshold-based
electrode connection status can be presented to the user (step
645), or can trigger a "poor connection" warning during recording
(step (650). The test signal frequency and the time between
impedance measurements may be changed depending on whether a
recording is in progress and/or the user has paused an active
recording to check the impedance (step 655): [0131] 1. Before
recording or while a recording is paused: impedance test signal may
be set to a frequency that is within the normal EEG band (for
example, between 1 Hz to 150 Hz, such as 31 Hz); measurements may
be acquired in near real time, e.g. every .about.2 seconds. [0132]
a. This mode may allow the user to get immediate connection quality
feedback when setting up the device or fixing a poor connection
during a (paused) recording. [0133] b. The test signal frequency
may be within the EEG band, making the raw EEG unusable during the
measurement period, but may give an impedance measurement at a
frequency that is relevant to EEG. [0134] 2. During recording:
impedance test signal may be set to a frequency that is outside the
normal EEG band (e.g., 125 Hz); measurements may be acquired less
frequently, e.g. every minute. [0135] a. This mode may allow the
device to monitor electrode connection quality and may
automatically alert the user to problems, without interfering with
the recording. [0136] b. The test signal frequency may be outside
the EEG band which may allow it to be filtered from the raw EEG
data.
[0137] Although the above steps show method 600 of assessing
connection quality in accordance with many embodiments, a person of
ordinary skill in the art will recognize many variations based on
the present disclosure. The steps may be completed in different
order. Steps may be added or deleted. Some of the steps may
comprise sub-steps. Many of the steps may be repeated as often as
beneficial to assessing connection quality.
[0138] One or more of the steps of the method 600 may be performed
with the circuitry as described herein, for example, one or more of
the processor or logic circuitry such as those of the digital
processor system 260. The circuitry may be programmed to provide
one or more of the steps of the method 600, and the program may
comprise program instructions stored on a computer readable memory
or programmed steps of the logic circuitry such as the programmable
array logic or the field programmable gate array, for example.
[0139] FIG. 7A shows an exemplary electrode check screen user
interface 700 displaying connection quality of various electrodes.
The user may find it difficult to intuitively understand the
difference between impedance measurements themselves (e.g., 5
k.OMEGA. vs. 10 k.OMEGA. electrode impedances), and often, the
dynamic range of the measurement corresponding to a poor connection
(e.g., both 101 k.OMEGA. and 900 k.OMEGA. may correspond to a poor
connection, and the user's action is likely the same in either
case). The impedance calculated by method 600 described above may
be correlated to scale which may be simpler and more useful to a
user. The impedance measurements may then be presented in a more
intuitive manner as shown in user interface 700 such that the user
can quickly assess the state of each electrode, and whether the
impedance is changing due to their efforts to improve the
connection.
[0140] The impedance measurements may be mapped to a nonlinear
numerical scale and presented to the user with a color-coded or
otherwise patterned electrode status indicators that are visually
perceptible in user interface 700. The user interface 700 may
include a legend 705 to indicate which color or pattern indicates a
good electrode connection 705-1, a marginal electrode connection
705-2, and a bad electrode connection 705-3. The user interface 700
includes a graphical representation 710 of electrode positions on
the patient's head, including graphical representations 715-n of
the electrodes themselves and their respective connection quality
(i.e., electrode representations 715-1, 715-2, 715-3, 715-4, 715-5,
715-6, 715-7, 715-8, 715-9, 715-10). During times when the user may
be adjusting the electrodes, i.e., during setup or when recording
is paused, a number indicating connection quality is displayed next
to each electrode or electrode representation 715-n. In some
embodiments, this number can range from 0 to 99, and may be scaled
nonlinearly from the measured impedance. For example: [0141] If
measured impedance (k.OMEGA.) is in the range [0, 30), scaled
value=a.sub.1(impedance).sup.b1+c.sub.1.fwdarw.[1, 9) [0142] If
measured impedance (k.OMEGA.) is in the range [30, 70), scaled
value=a.sub.2(impedance).sup.b2+c.sub.2.fwdarw.[10, 60) [0143] If
measured impedance (k.OMEGA.) is in the range [70, 100), scaled
value=a.sub.3(impedance).sup.b3+c.sub.3.fwdarw.[60, 90) [0144] If
measured impedance (k.OMEGA.) is in the range [100+], scaled
value=a.sub.4(impedance).sup.b4+c.sub.4.fwdarw.[90, 99) Where
a.sub.n, b.sub.n, and c.sub.n are constants.
[0145] The displayed scaled value may compress the upper range of
the measured impedance (poor connection) and expand the lower range
(good connection), which can give the user continuous feedback in
the form of a smoothly decreasing number as the connection quality
improves while the skin is prepped, or the electrodes are adjusted,
etc.
[0146] The graphical representation of the electrode 715-n then
changes colors or patterns based on the scaled impedance value,
which can indicate in an immediately recognizable way whether all
electrodes have acceptable connection quality, or whether some need
to be adjusted. For example: [0147] Scaled value in the range 1-10
(good electrode connection): Green electrode [0148] For example,
electrodes or electrode representations 715-1, 715-2, 715-3, 715-5,
715-6, 715-7 in user interface 700 (FIG. 7) [0149] Scaled value in
the range 11-30 (marginal electrode connection): Yellow electrode
[0150] For example, electrodes or electrode representations 715-4,
715-8 in user interface 700 (FIG. 7) [0151] Scaled value in the
range 31-99 (bad electrode connection): Red electrode [0152] For
example, electrodes or electrode representations 715-9, 715-10 in
user interface 700 (FIG. 7)
[0153] During an ongoing recording, the scaled numerical values may
not be shown, and only the color-coded electrodes may be displayed.
This can allow the user to determine at a glance whether any
electrodes need to be adjusted, and whether they should pause the
recording to adjust electrodes using the increased feedback
granularity afforded by the scaled numerical values.
[0154] The thresholds at which the electrode graphics 715-n will
change colors or patterns can be user-adjustable depending on the
application, and the user's needs or preferences.
[0155] FIG. 7B is a flow chart showing a method 750 of correlating
impedance measurements with connection quality assessments and
displaying the connection quality assessment to the user.
[0156] In a step 760, the impedance(s) of the electrode(s) may be
determined, such as in accordance with method 600 described
above.
[0157] In a step 770, the impedance(s) of the electrode(s) may be
scaled, such as in the manner described above. In a sub-step 775,
for example, the impedance(s) may be nonlinearly scaled to within a
predefined range of values such as between 0 and 99.
[0158] In a step 780, the scaled impedance measurement(s) may be
sorted into qualitative categories, such as (i) good connection
quality, (ii) marginal connection quality, and (iii) poor
connection quality as described above. In a sub-step 783, for
example the scaled impedance measurement(s) may be sorted based on
their value ranges such as (i) values between 1-10 being sorted
into the good connection quality category, (ii) values between
11-30 being sorted into the marginal connection quality category,
and (iii) values between 31-99 being sorted into the poor quality
connection category. The value ranges for each of the qualitative
categories may be preset or predetermined, or they may be user
defined in a sub-step 786.
[0159] In a step 790, the visual representation(s) of the
electrode(s) and their connection quality may be displayed visually
such as with user interface 700 shown in FIG. 7B. As described
above, the user interface 700 may further include a representation
of the patient's head as displayed by a step 793 and a connection
quality legend as displayed by a step 796.
[0160] Although the above steps show method 750 of providing
electrode connection quality assessments to a user in accordance
with many embodiments, a person of ordinary skill in the art will
recognize many variations based on the present disclosure. The
steps may be completed in different order. Steps may be added or
deleted. Some of the steps may comprise sub-steps. Many of the
steps may be repeated as often as beneficial to assessing
connection quality.
[0161] One or more of the steps of the method 750 may be performed
with the circuitry as described herein, for example, one or more of
the processor or logic circuitry such as those of the digital
processor system 260. The circuitry may be programmed to provide
one or more of the steps of the method 750, and the program may
comprise program instructions stored on a computer readable memory
or programmed steps of the logic circuitry such as the programmable
array logic or the field programmable gate array, for example.
[0162] Measurements and displays of electrode connection quality
may not only assist with the user in optimizing electrode
connection prior to measuring the bioelectrical signals of interest
or applying electrostimulation, but may also be useful with the
user in analyzing the bioelectrical signal(s) measured. For
example, the user may choose to discount the bioelectrical
signal(s) that are taken with electrode(s) of poor or marginal
electrode connection quality and/or may choose to particularly note
the bioelectrical signal(s) that are taken with electrode(s) of
good connection quality. The user may do this in real-time as a
displayed user interface concurrently show the bioelectrical
signal(s) and connection quality assessments. Alternatively or in
combination, the bioelectrical signal(s) may be recorded and stored
along with their connection quality assessments for subsequent
analysis. FIG. 8 shows an exemplary user interface 800 displaying
bioelectrical signal readings 820 as sorted by the electrode pair
810 measuring the respective bioelectrical signal. The
bioelectrical signal readings 820 may include one or more tags 830
to indicate electrode connection quality at the time of the
measurement of the bioelectrical signal.
[0163] While preferred embodiments of the present disclosure have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
scope of the present disclosure. It should be understood that
various alternatives to the embodiments of the present disclosure
described herein may be employed in practicing the inventions of
the present disclosure. It is intended that the following claims
define the scope of the invention and that methods and structures
within the scope of these claims and their equivalents be covered
thereby.
* * * * *