U.S. patent number RE43,050 [Application Number 11/121,327] was granted by the patent office on 2011-12-27 for medical electrode and release liner configurations facilitating packaged electrode characterization.
This patent grant is currently assigned to Koninklijke Philips Electronics N.V.. Invention is credited to Hans Patrick Griesser, Kim J. Hansen, Eric L. Jonsen, Thomas D. Lyster, Carlton B. Morgan, Daniel J. Powers, David E. Snyder, Thomas Solosko.
United States Patent |
RE43,050 |
Lyster , et al. |
December 27, 2011 |
Medical electrode and release liner configurations facilitating
packaged electrode characterization
Abstract
An electrode includes a conductive adhesive layer and a
conductive foil layer having a void therein. One such electrode may
be mounted in conjunction with another electrode upon a release
liner having one or more openings therein to facilitate electrical
signal exchange between electrodes. A release liner may include a
moisture permeable and/or moisture absorbent membrane. A release
liner may alternatively include a conductive backing layer. A
release liner may also include an insulating swatch covering an
opening. A release liner may be implemented as a foldable sheet,
such that multiple electrodes may be mounted upon the same side of
the foldable sheet. A medical device to which the mounted
electrodes are coupled may characterize the electrical path between
the electrodes. The medical device may perform a variety of
electrical measurements, including real and/or complex impedance
measurements. Based upon one or more measurements, the medical
device may provide an indication of electrode condition, fitness
for use, and/or an estimated remaining lifetime. An electrode
condition indicator, which may form a portion of the medical
device, may generate, present, or display electrode condition
and/or estimated remaining lifetime information via a visual
metaphor, such as a fuel gauge.
Inventors: |
Lyster; Thomas D. (Bothell,
WA), Solosko; Thomas (Issaquah, WA), Morgan; Carlton
B. (Bainbridge Island, WA), Hansen; Kim J. (Renton,
WA), Powers; Daniel J. (Issaquah, WA), Griesser; Hans
Patrick (Bainbridge Island, WA), Jonsen; Eric L.
(Seattle, WA), Snyder; David E. (Bainbridge Island, WA) |
Assignee: |
Koninklijke Philips Electronics
N.V. (Eindhoven, NL)
|
Family
ID: |
25495873 |
Appl.
No.: |
11/121,327 |
Filed: |
May 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09954750 |
Sep 14, 2001 |
6694193 |
Feb 17, 2004 |
|
|
Current U.S.
Class: |
607/142 |
Current CPC
Class: |
A61N
1/0492 (20130101); A61N 1/046 (20130101); A61N
1/3925 (20130101); A61N 2001/37294 (20130101) |
Current International
Class: |
A61N
1/04 (20060101) |
Field of
Search: |
;607/142-156
;600/372-392 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Getzow; Scott M
Attorney, Agent or Firm: Yorks, Jr.; W. Brinton
Claims
What is claimed is:
.[.1. A release liner comprising: a release layer, said release
layer having an opening therein; and one from the group of a
moisture permeable membrane and a moisture absorbent membrane, the
membrane covering the opening..].
.[.2. The release liner of claim 1, wherein the membrane comprises
paper..].
.[.3. The release liner of claim 1, wherein the membrane is
maintained in a position via attachment to the release
layer..].
4. A release liner comprising: a first release layer; one from the
group of a moisture permeable membrane and a moisture absorbent
membrane; and a second release layer, wherein the first release
layer includes an opening therein, and wherein the second release
layer includes an opening therein.
5. The release liner of claim 4, wherein the membrane comprises
paper.
.Iadd.6. An electrode system for a medical device employing an
electrode to exchange signals with a subject comprising: a
conductive adhesive layer; and a conductive layer affixed to the
conductive adhesive layer, the conductive layer having a
nonconductive region therein, wherein the conductive adhesive layer
overlays the nonconductive region, wherein the conductive adhesive
layer and the conductive layer comprise a first electrode; and
further comprising: a second conductive adhesive layer; a second
conductive layer affixed to the second conductive adhesive layer,
the second conductive layer having a nonconductive region therein,
the second conductive adhesive layer overlaying the nonconductive
region of the second conductive layer, wherein the second
conductive adhesive layer and the second conductive layer comprise
a second electrode; and a release liner, located between the
conductive adhesive layers of the first and second electrodes, the
release liner having a a first release layer, one from the group of
a moisture permeable membrane and a moisture absorbent membrane,
and a second release layer, wherein the first release layer
includes an opening therein, and wherein the second release layer
includes an opening therein, and further wherein the conductive
adhesive layers of the first and second electrodes are electrically
connected in the vicinity of the nonconductive
regions..Iaddend.
.Iadd.7. The electrode system of claim 6, wherein the nonconductive
regions comprise voids in the conductive layers..Iaddend.
.Iadd.8. The electrode system of claim 6, further comprising: a
first lead wire electrically coupled to the conductive layer of the
first electrode; a second lead wire electrically coupled to the
conductive layer of the second electrode; and a measurement
circuit, located in the medical device, and electrically coupled to
the first and second lead wires, and operable to measure an
electrical characteristic of the conductive adhesive
layers..Iaddend.
.Iadd.9. The electrode system of claim 8, wherein the measurement
circuit is operable to measure at least one of a current or
impedance of the conductive adhesive layers..Iaddend.
.Iadd.10. The electrode system of claim 6, wherein the low
impedance region of the release liner is smaller than the
nonconductive regions of the conductive layers..Iaddend.
.Iadd.11. An electrode system for a medical device employing an
electrode to exchange signals with a subject comprising: a
conductive adhesive layer having a lateral dimension and a
thickness dimension; an electrical conductor electrically coupled
to the conductive adhesive layer; and a conductive layer having a
lateral dimension and affixed to the conductive adhesive layer with
its lateral dimension substantially in parallel with the lateral
dimension of the conductive adhesive layer, the conductive layer
constraining the passage of current in at least a portion of the
shortest current path between the conductive layer and the
electrical conductor to be in the lateral dimension of the
conductive adhesive layer; wherein the conductive layer and the
affixed conductive adhesive layer comprise a first electrode;
wherein the electrical conductor comprises a second electrode
having a conductive layer and an affixed conductive adhesive layer;
and a release liner to which the conductive adhesive layers of the
first and second electrodes are attached, the release liner having
a first release layer, one from the group of a moisture permeable
membrane and a moisture absorbent membrane, and a second release
layer, wherein the first release layer includes an opening therein,
and wherein the second release layer includes an opening therein to
form a low impedance region which electrically couples the
conductive adhesive layer of the first electrode to the second
electrode..Iaddend.
.Iadd.12. The electrode system of claim 11, wherein the conductive
layer of the first electrode has a high impedance region therein;
wherein the low impedance region of the release liner opposes the
high impedance region of the conductive layer across the thickness
dimension of the conductive adhesive layer of the first
electrode..Iaddend.
.Iadd.13. The electrode system of claim 12, wherein the low
impedance region of the release liner is smaller than the high
impedance region of the conductive layer..Iaddend.
.Iadd.14. The electrode system of claim 13, wherein the passage of
current is constrained to the lateral dimension of the conductive
adhesive layer of the first electrode where the high impedance
region of the conductive layer opposes the release liner adjacent
to the low impedance region of the release liner..Iaddend.
.Iadd.15. An electrode system for a medical device employing an
electrode to exchange signals with a subject comprising: a release
liner having a first release layer, one from the group of a
moisture permeable membrane and a moisture absorbent membrane, and
a second release layer, wherein the first release layer includes an
opening therein, and wherein the second release layer includes an
opening therein to form a low impedance region; a first electrode
having a conductive adhesive layer overlaying a surface of a
conductive layer, the conductive adhesive layer having a thickness
dimension which is orthogonal to the surface of the conductive
layer and a lateral dimension, the conductive adhesive layer
transporting current between the conductive layer and the low
impedance region of the release liner in the lateral dimension of
the conductive adhesive layer during a test mode..Iaddend.
.Iadd.16. An electrode system for a medical device employing an
electrode to exchange signals with a subject comprising: a release
liner having a first release layer, one from the group of a
moisture permeable membrane and a moisture absorbent membrane, and
a second release layer, wherein the first release layer includes an
opening therein, and wherein the second release layer includes an
opening; a first electrode attached to the first release layer of
the release liner and having a conductive adhesive layer overlaying
a conductive layer; a second electrode attached to the second
release layer of the release liner and having a conductive adhesive
layer overlaying a conductive layer, the conductive adhesive layer
of the second electrode being electrically coupled to the
conductive adhesive layer of the first electrode, wherein the
conductive adhesive layer of the first electrode is in contact with
the conductive adhesive layer of the second electrode through a low
impedance region of the release liner, wherein the impedance
between the conductive layers of the electrodes is outside the
expected impedance range of the subject..Iaddend.
.Iadd.17. The electrode system of claim 16, wherein the thickness
of the conductive adhesive layer of the first electrode exhibits a
first impedance; wherein the thickness of the conductive adhesive
layer of the second electrode exhibits a second impedance; and
wherein the impedance between the conductive layers of the
electrodes is greater than the sum of the first and second
impedances..Iaddend.
.Iadd.18. The electrode system of claim 17, wherein the impedance
between the conductive layers of the electrodes includes a current
path through a conductive adhesive layer which is orthogonal to the
thickness dimension of the conductive adhesive layer..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the testing of medical
electrodes that are mounted on a release liner. More particularly,
the invention is directed to various electrode and/or release liner
embodiments that facilitate testing and characterization of
packaged electrodes.
2. Description of the Background Art
Sudden Cardiac Arrest (SCA) is one of the leading causes of death
in the industrialized world. SCA typically results from an
arrhythmia condition known as Ventricular Fibrillation (VF), during
which a patient's heart muscle exhibits extremely rapid,
uncoordinated contractions that render the heart incapable of
circulating blood. Statistically, after four minutes have elapsed,
the patient's chance of survival decreases by 10% during each
subsequent minute they fail to receive treatment.
An effective treatment for VF is electrical defibrillation, in
which a defibrillator delivers an electrical pulse, waveform, or
shock to the patient's heart. Because the onset of VF is generally
an unpredictable event, the likelihood that a victim will survive
increases dramatically if 1) defibrillation equipment is nearby; 2)
such equipment is in proper working order; and 3) such equipment
may be easily, rapidly, and effectively deployed to treat the
patient.
Medical equipment manufacturers have developed Automated External
Defibrillators (AEDs) that minimally trained personnel may use to
perform electrical defibrillation when emergency situations arise.
AEDs may be found in a variety of non-medical settings, including
residences, public buildings, businesses, private vehicles, public
transportation vehicles, and airplanes.
An AED relies upon a set of electrodes to deliver a series of
shocks to a patient. An electrode therefore serves as a physical
and electrical interface between the AED and the patient's body. In
general, an electrode may comprise a conductive foil layer that
resides upon a conductive adhesive layer; a lead wire that couples
the foil layer to the AED; and an insulating layer that covers the
foil layer. The conductive adhesive layer physically and
electrically interfaces the foil layer to a patient's skin. New or
unused electrodes reside upon a release liner, from which an
operator may peel off an electrode prior to placement upon a
patient's body. During manufacture, electrodes upon their release
liner are typically sealed in a package.
An AED is likely to be used infrequently; however, any given use
may involve a time critical, life threatening situation. Thus, it
is imperative that the AED be able to provide an indication of its
operating condition at essentially any time. While in a quiescent
state, an AED generally performs periodic diagnostic sequences to
determine its current operating condition. Such sequences may be
performed, for example, on a daily and/or weekly basis. The
diagnostic sequences include tests for characterizing the current
path between the AED and a set of electrodes. Hence, the electrodes
must be connected to the AED while the AED is in its quiescent
state, and the electrodes must be electrically testable while
mounted on their release liner. As a result, release liners
providing electrical contact between electrodes have been
developed.
Such release liners generally include multiple openings that
facilitate electrical contact between electrodes. The current path
between the AED and the electrodes includes each electrode's lead
wire, foil layer, and conductive adhesive layer. For a pair of new,
properly functioning conventional electrodes mounted upon a release
liner having multiple openings, this current path may be
characterized by an impedance value ranging between 2 and 10 Ohms.
If an impedance measurement indicates an electrical discontinuity
or open circuit condition exists, a lead wire or connector coupling
an electrode to the AED may be damaged, and/or an electrode may be
improperly connected to the AED. Similarly, if an impedance
measurement indicates a short or open circuit condition exists, one
or more electrodes, a lead wire or other wire within the current
path, and/or a connector that couples the electrodes to the AED may
be damaged or defective.
A measurement indicating a higher than desired impedance may arise
when an electrode is damaged, deteriorated, and/or degraded. An
electrode's conductive adhesive layer typically comprises a
hydrogel film, which itself comprises natural and/or synthetic
polymers dispersed or distributed in an aqueous fluid. The
electrical properties of the hydrogel film are dependent upon its
moisture content. If the hydrogel possesses appropriate water
content, it provides a low impedance electrical path between the
electrode's foil layer and a patient's skin. The hydrogel film,
however, dries out over time. As a result, its impedance increases
over time, thereby undesirably decreasing its effectiveness for
signal exchange and energy transfer between a patient and an AED.
Once moisture loss has reached a certain level, the hydrogel film,
and hence the electrode of which it forms a part, may be unsuitable
for use.
A patient's transthoracic impedance typically falls within a range
of 25 to 200 Ohms. As electrodes' hydrogel film deteriorate over
time, the impedance associated with the electrical path provided by
the electrodes may overlap with the typical transthoracic impedance
range. Thus, if an AED in a normal operational or "on" state
measures an electrode impedance corresponding to a patient's
transthoracic impedance, the AED has no inherent way of determining
whether partially deteriorated electrodes are currently mounted
upon their release liner, or properly functioning electrodes are
connected to the patient.
Prior release liners that facilitate electrical testing of
electrodes mounted thereupon have typically been unnecessarily
complex, expensive to manufacture, unacceptable relative to
difficulty of electrode removal, and/or limited relative to the
extent to which they permit accurate characterization of an
electrode's hydrogel film. A need exists for electrodes and/or
release liners that overcome the aforementioned deficiencies.
SUMMARY OF THE INVENTION
The present invention includes a number of release liner,
electrode, and/or medical or measuring device embodiments that
facilitate electrical characterization of one or more electrodes
coupled to the medical or measuring device. In the context of the
present invention, a medical device may be essentially any device
capable of using electrodes to receive signals from and/or deliver
signals and/or energy to a patient's body. A measuring device may
be essentially any device capable of electrically characterizing
packaged electrodes.
In one embodiment, a release liner comprises a release layer and a
moisture-permeable and/or moisture-absorbent membrane or sheet. The
release layer may include an opening therein, over which the
membrane may reside. When electrodes are positioned or mounted upon
the release liner, the electrodes' conductive adhesive or hydrogel
layers may transfer moisture to the membrane, thereby forming a low
impedance electrical path that facilitates electrical communication
between electrodes. The membrane may be prewetted or premoistened
prior to mounting electrodes upon the release layer to minimize
electrode moisture loss.
The release layer may comprise a single, foldable sheet that
surrounds or partially surrounds the membrane. A pair of electrodes
residing upon the same side of the foldable sheet may exchange
electrical signals. Alternatively, a first and a second release
layer may encase or enclose one or more portions of the membrane,
where each release layer includes an opening. In another release
liner embodiment, a membrane may extend beyond a border of a single
release layer that lacks openings. Electrodes mounted upon the
release layer in such an embodiment also extend beyond the release
layer border, and contact the membrane to facilitate electrical
communication therebetween.
A release liner and electrode package according to an embodiment of
the invention may comprise a rigid cartridge having an electrical
interface incorporated therein; a release liner having a set of
openings therein; and a set of electrodes mounted upon the release
liner. The openings in the release liner facilitate electrical
communication between electrodes. The rigid cartridge provides an
environment characterized by well-defined internal conditions,
where moisture transfer in or out of the rigid cartridge is minimal
or essentially eliminated. Such a package may therefore prolong
electrode lifetime.
A release liner according to another embodiment of the invention
may comprise a release layer upon which a conductive strip resides.
Electrodes may be mounted in a side-by-side manner upon the release
layer, and may exchange electrical signals via the conductive
strip. The release layer may comprise a foldable sheet. In an
alternate embodiment, the conductive strip may wrap around or
encircle the release layer, facilitating electrical communication
between electrodes mounted on opposite sides of the release
layer.
A release liner according to another embodiment of the invention
may comprise a release layer having a set of openings therein, and
a conductive backing layer. The release layer may comprise a
foldable sheet. Electrodes may be mounted upon such a release liner
in a side by side manner. An electrical signal may travel from one
electrode, through an opening in the release layer, through or
within the conductive backing layer, through another opening in the
release layer, and into another electrode.
The conductive backing layer may comprise a metal, or a conductive
adhesive layer such as a hydrogel layer. In the event that the
conductive backing layer comprises a conductive adhesive layer, an
electrical current traveling between mounted electrodes may follow
a path that is much greater than the thickness of the electrodes'
conductive adhesive layers. As a result, the measured impedance of
the release liner may be greater than typical patient impedance
ranges, and may exhibit a high degree of sensitivity to conductive
adhesive layer degradation over time.
A release liner according to another embodiment of the invention
may comprise a first release layer or sheet, a second release layer
or sheet, and an intervening conductive adhesive layer. The first
and second release layers each include an opening. The first and
second release layers are oriented or positioned such that their
openings are offset relative to each other by a separation
distance. Electrodes mounted upon the release layers may exchange
electrical signals with each other via the release layer openings
and the conductive adhesive layer between the release layers. Such
electrical signals may travel through a length of conductive
adhesive layer that is much greater than the thickness of the
electrodes' conductive adhesive layers, in a manner analogous to
that described above. In an alternate embodiment, a release liner
may comprise a foldable sheet that surrounds or encases one or more
portions of a conductive adhesive or hydrogel layer. The foldable
sheet may include openings, which are offset relative to each other
in accordance with a given separation distance when the foldable
sheet surrounds or encases portions of the conductive adhesive
layer.
An electrode according to an embodiment of the invention may
comprise a conductive adhesive layer coupled to a conductive foil
layer that includes one or more voids therein. Each void affects
electrical current flow through the electrode's conductive adhesive
layer when the electrode is mounted upon a release liner that
facilitates electrical communication between electrodes. In
particular, the presence of a void may cause transverse electrical
current flow through the electrode's conductive adhesive layer,
rather than simply current flow through the conductive adhesive
layer's thickness. This results in a longer electrical path, which
in turn may provide the voided electrode with an impedance that is
greater than typical patient impedance levels. Additionally,
impedance measurements along this electrical path may exhibit a
significant degree of sensitivity to changes in conductive adhesive
layer properties over time.
An electrode may include or incorporate one or more insulating
swatches between its conductive foil layer and conductive adhesive
layers. When the electrode is mounted upon a release liner that
facilitates electrical communication between electrodes, the
presence of an insulating swatch may result in transverse current
flow through the electrode's conductive adhesive layer in a manner
analogous to that described above for the voided electrode.
An electrode according to another embodiment of the invention may
comprise a conductive foil layer, a conductive adhesive layer, and
a sonomicrometer or ultrasonic transducer. When electrodes that
incorporate ultrasonic transducers are mounted upon a release
liner, ultrasonic signals transmitted and/or received via the
ultrasonic transducers may be used to indicate an electrode
separation distance. The electrode separation distance may indicate
whether electrodes are mounted upon a release liner or a patient's
body.
In accordance with the present invention, various types of
electrodes may be mounted upon release liners that facilitate
exchange of electrical signals between electrodes. A medical device
to which such electrodes are coupled may perform a variety of
measurements to characterize electrode condition or fitness for
use. The medical device may measure a short or open circuit
condition, which may indicate an electrical path problem. As one or
more electrodes' conductive adhesive layers degrade over time, the
medical device may measure increasing impedance levels. If an
impedance level exceeds a given threshold value or range, the
medical device may provide an indication that the electrodes are
non-optimal or until for use. The medical device may alternately or
additionally provide an indication of electrode condition or
fitness for use at particular times or time intervals. The medical
device may further calculate or determine a time remaining before
an electrode or electrode pair may no longer be fit for use. Such a
calculation or determination may be based upon a current
degradation curve.
In accordance with an embodiment of the invention, a release liner
that lacks openings may serve as a capacitive medium between
electrodes mounted thereupon. A medical device may perform a
capacitance measurement to electrically characterize an electrical
path corresponding to the electrodes and release liner.
In accordance with another embodiment of the invention, a release
liner may comprise a release layer that includes an opening, and an
insulating swatch or patch that covers or resides within the
opening. Electrodes may be mounted upon the release layer such that
the electrodes' conductive adhesive layers cover the opening, and
at least one electrode's conductive adhesive layer covers the
swatch.
A medical device may perform a complex impedance measurement upon
electrodes mounted upon a release liner having such a swatch. When
one or more such electrodes include a void or internal swatch as
described above, the result of the complex impedance measurement
may exhibit significant dependence upon the current condition of
such electrodes' conductive adhesive layers. The medical device may
therefore determine an extent to which one or more electrodes are
fit for use. The medical device may further provide a visual and/or
other indication of electrode condition and/or fitness for use.
A medical device such as an Automated External Defibrillator (AED)
may include or incorporate elements for periodically determining
electrode condition or status. The medical device may include a
status measurement unit, which may operate in conjunction with an
electrode condition indicator, a display device, a speaker, and/or
other elements in a variety of manners to indicate electrode
condition, fitness for use, and/or an estimated remaining electrode
lifetime. In accordance with an embodiment of the invention, an
electrode condition indicator may incorporate, generate, and/or
present one or more types of visual metaphors that provide an
indication of electrode status, condition, and/or estimated
remaining lifetime. A visual metaphor may correspond to a fuel
gauge, and may convey positional and/or color relationships between
one or more indicating elements that change or vary over time in
accordance with measured and/or estimated electrode properties. The
visual metaphor may further convey textual and/or symbolic
information.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a layered perspective view of a release liner according
to an embodiment of the invention.
FIG. 1B is a perspective view of electrodes mounted upon the
release liner of FIG. 1A.
FIG. 1C is a perspective view of a release liner according to
another embodiment of the invention, and a manner of mounting
electrodes thereupon.
FIG. 2A is a perspective view of a release liner according to
another embodiment of the invention.
FIG. 2B is a perspective view of electrodes mounted upon the
release liner of FIG. 2A.
FIG. 3A is a layered perspective view of a release liner according
to another embodiment of the invention.
FIG. 3B is a perspective view of electrodes mounted upon the
release liner of FIG. 3A.
FIG. 4 is a perspective view of a release liner and an electrode
package according to an embodiment of the invention.
FIG. 5A is a plan view of a release liner according to another
embodiment of the invention.
FIG. 5B is a plan view of electrodes mounted upon the release liner
of FIG. 5A.
FIG. 6A is a perspective view of another embodiment of a release
liner according to the invention.
FIG. 6B is a perspective view of electrodes mounted upon the
release liner of FIG. 6A.
FIG. 7 is a perspective view of a release liner according to
another embodiment of the invention, and a manner of mounting
electrodes upon the same.
FIG. 8A is a layered perspective view of a release liner according
to another embodiment of the invention.
FIG. 8B is a perspective view of electrodes mounted upon the
release liner of FIG. 8A.
FIG. 9A is a perspective view of a release liner according to
another embodiment of the invention.
FIG. 9B is a perspective view showing electrodes mounted upon the
release liner of FIG. 9A.
FIG. 10A is a layered plan view of a release liner according to
another embodiment of the invention.
FIG. 10B is a perspective view of electrodes mounted upon the
release liner of FIG. 10A.
FIG. 11A is a perspective view of a release liner according to
another embodiment of the invention.
FIG. 11B is a perspective view of electrodes mounted upon the
release liner of FIG. 1A.
FIG. 12A is a cross sectional view of an electrode according to an
embodiment of the invention.
FIG. 12B is a plan view of the electrode of FIG. 12A.
FIG. 12C is a plan view of an electrode according to another
embodiment of the invention.
FIG. 12D is a cross sectional view of an electrode according to
another embodiment of the invention.
FIG. 12E is a plan view of the electrode of FIG. 12D.
FIG. 13A is a graph of exemplary current density relative to
lateral position for a conventional electrode mounted upon a
patient's body.
FIG. 13B is a graph of exemplary current density relative to
lateral position beneath elements of the electrode of FIG. 12A when
the electrode is mounted upon a patient's body.
FIG. 14A is a perspective view of electrodes of FIG. 12A mounted
upon a release liner according to another embodiment of the
invention.
FIG. 14B is a cross sectional view of electrodes of FIG. 12A
mounted upon the release liner of FIG. 14A.
FIG. 15 is a plan view of the electrode of FIG. 12A and a
conventional electrode mounted upon the release liner of FIG.
8A.
FIG. 16 is a plan view of electrodes of FIG. 12D mounted upon the
release liner of FIG. 8A.
FIG. 17 is a cross sectional view of an electrode according to
another embodiment of the invention.
FIG. 18 is a perspective view of electrodes of FIG. 17 mounted upon
the release liner of FIG. 14A.
FIG. 19 is a perspective view of electrodes of FIG. 12C and a
conventional electrode mounted upon a release liner according to
another embodiment of the invention.
FIG. 20 is a perspective view of electrodes mounted upon a release
liner in accordance with another embodiment of the invention.
FIG. 21A is a plan view of a release liner according to another
embodiment of the invention.
FIG. 21B is a perspective view of electrodes mounted upon the
release liner of FIG. 21A.
FIG. 21C is a cross sectional view of an electrode to release liner
assembly of FIG. 21B.
FIG. 21D is an equivalent circuit corresponding to the electrode to
release liner assembly of FIG. 21B.
FIG. 22A is a perspective view of an electrode of FIG. 12A and a
conventional electrode mounted upon the release liner of FIG.
21A.
FIG. 22B is a cross sectional view of a voided electrode to release
liner to conventional electrode assembly of FIG. 22A.
FIG. 22C is an equivalent circuit corresponding to the voided
electrode to release liner to conventional electrode assembly of
FIG. 22A.
FIG. 23A is a perspective view of electrodes of FIG. 12A mounted
upon the release liner of FIG. 21A.
FIG. 23B is a cross sectional view of a voided electrode to release
liner to voided electrode assembly of FIG. 23A.
FIG. 23C is an equivalent circuit corresponding to the voided
electrode to release liner to voided electrode assembly of FIG.
23A.
FIG. 24A is a layered plan view of a release liner according to
another embodiment of the invention.
FIG. 24B is a plan view of a conventional electrode and an
electrode of FIG. 12A mounted upon the release liner of FIG.
24A.
FIG. 25A is a plan view of a release liner according to another
embodiment of the invention.
FIG. 25B is a perspective view of electrodes of FIG. 12A mounted
upon the release liner of FIG. 25A.
FIG. 26 is a perspective view of a release liner according to
another embodiment of the invention, and electrodes of FIG. 12A
mounted thereupon.
FIG. 27 is a block diagram of an Automated External Defibrillator
coupled to a set of electrodes mounted upon a release liner in
accordance with the present invention.
FIG. 28A is an illustration of an electrode condition indicator in
accordance with an embodiment of the invention.
FIG. 28B is an illustration of an electrode condition indicator in
accordance with another embodiment of the invention.
FIG. 29A is an illustration of a remaining time indicator in
accordance with an embodiment of the invention.
FIG. 29B is an illustration of a remaining time indicator in
accordance with another embodiment of the invention.
FIG. 30 is a perspective view of a package incorporating an
electrode condition and/or remaining time indicator and electrodes
mounted upon a release liner.
FIG. 31 is a block diagram of an Automated External Defibrillator
that includes an electrode condition indicator and/or an estimated
remaining electrode lifetime indicator.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following discussion is presented to enable a person skilled in
the art to make and use the invention. The general principles
described herein may be applied to embodiments and applications
other than those detailed below without departing from the spirit
and scope of the present invention as defined by the appended
claims. The present invention is not intended to be limited to the
embodiments shown, but is to be accorded the widest scope
consistent with the principles and features disclosed herein.
The present invention encompasses a wide variety of release liner
and/or electrode embodiments that facilitate automatic electrical
characterization of one or more packaged electrodes coupled to a
medical or measuring device. In the context of the present
invention, a medical device may be essentially any type of device
capable of employing a set of electrodes to exchange signals with a
patient. For example, the medical device may be a defibrillator; a
cardiac pacing system; an electrocardiograph (ECG) or patient
monitoring system; or an electrosurgery device. Since electrode
fitness is of particular concern in relation to medical devices
designed to provide emergency resuscitation capabilities, the
description herein most commonly considers release liners and/or
electrodes suitable for deployment with defibrillators,
particularly Automated External Defibrillators (AEDs).
Relative to the present invention, a measuring device may be
essentially any type of device capable of performing electrical
measurements upon electrodes designed and/or packaged or mounted
upon a release liner in accordance with the present invention. A
measuring device need not include patient monitoring and/or
treatment elements, but may comprise, for example, a power supply
and a multimeter. Alternatively, a measuring device may comprise an
LCR meter. Portions of the description herein that refer to
packaged electrode characterization via a medical device may apply
equally to packaged electrode characterization via a measuring
device.
With respect to any or essentially any of the electrode and/or
release liner embodiments described herein, a medical or measuring
device may perform electrical characterization measurements and/or
tests via conductive pathways, lead wires, and/or connectors
associated with normal electrode configurations and/or normal
electrode use. That is, the electrode and/or release liner
embodiments detailed herein may require no additional couplings to
a medical or measuring device beyond those that facilitate normal
signal exchange between a patient and a medical device.
In accordance with the present invention, a medical or measuring
device may include temperature measurement and/or compensation
circuitry or elements to account and/or compensate for the effects
of temperature variations upon the measured values of electrical
parameters. A medical or measuring device may adjust electrical
measurement and/or test parameters or criteria based upon one or
more temperature measurements to facilitate temperature compensated
characterization of electrodes mounted upon a release liner.
Temperature compensation capabilities may be of particular value in
medical or measuring devices that perform impedance measurements
such as those described in detail below.
A medical device operating in accordance with the present invention
may also include impedance compensation circuitry, such as that
described in U.S. Pat. No. 6,047,212, entitled "External
Defibrillator Capable of Delivering Patient Impedance Compensated
Biphasic Waveforms," which is incorporated herein by reference.
As described in detail below, a medical or measuring device may
perform one or more types of measurements upon electrodes mounted
upon a release liner. The medical or measuring device may perform
in-situ measurements at various intervals over time, and provide an
indication of current electrode condition and/or estimated
remaining lifetime based upon such measurements. As a result, in
contrast to the prior art, packaged electrodes designed and/or
deployed in accordance with the present invention may not require
associated markings or other information to define or specify an
expiration date or shelf life.
Packaged electrodes designed and/or deployed in accordance with the
present invention may include a wrapper, covering, label or the
like that includes an "install by" date that specifies a date by
which electrodes should be installed upon or coupled to a medical
or measuring device. The wrapper may be removed to facilitate
installation, after which the medical or measuring device may
determine when electrode replacement is required based upon
electrical measurements.
FIG. 1A is a layered perspective view of a release liner 100
according to an embodiment of the invention. In one embodiment, the
release liner 100 comprises a first release layer or sheet 110; a
second release layer or sheet 120; and a moisture-permeable
membrane 130. The first release layer 110 includes one or more
openings 112 disposed therein. Similarly, the second release layer
120 includes one or more openings 122, which may positionally
correspond to those in the first release layer 110.
Each release layer 110, 120 may comprise a nonconductive sheet
having non-stick properties. A given release layer 110, 120 may
comprise silicon-coated paper, polyester, polypropylene,
polyethylene, and/or other non-stick materials, in a manner well
understood by those skilled in the art. The openings 112, 122 in
each release layer 110, 120 may be cut, stamped, or punched out
using conventional techniques.
The moisture-permeable membrane 130 may comprise a nonconductive,
moisture-permeable and/or moisture-absorbent material, such as
litmus paper, that resides between the first and second release
layers 110, 120. While the moisture-permeable membrane 130 is
depicted in FIG. 1A as spanning an area approximately equal to that
of the first and second release layers 110, 120, the
moisture-permeable membrane 130 may be smaller, subject to the
requirement that it cover openings 112, 122 in the first and second
release layers 110, 120. Depending upon embodiment and/or
implementation details, the moisture-permeable membrane 130 may be
adhered, bonded, laminated, and/or otherwise attached to one, both,
or neither release layer 110, 120, as further detailed
hereafter.
In one embodiment, the release liner 100 may be manufactured such
that the moisture-permeable membrane 130 is bonded, adhered,
laminated, and/or otherwise attached to an inside surface of first
release layer 110. The second release layer 120 may be oriented or
positioned such that its openings 122 are essentially coincident
with the set of openings 112 in the first release layer 110.
Following any required positioning, the second release layer 120
may be bonded, adhered, laminated, and/or otherwise attached to the
moisture-permeable membrane 130 in a manner similar to that for the
first release layer 110.
FIG. 113 is a perspective view of electrodes 150 mounted upon the
release liner 100 of FIG. 1A. In one embodiment, each electrode 150
may be conventional, and comprises a conductive foil layer that
resides upon a conductive adhesive layer. The conductive adhesive
layer may comprise a conductive gel layer, such as a hydrogel
layer, in a manner well understood by those skilled in the art. In
general, the electrical properties of the conductive adhesive layer
may degrade over time, which may occur as a result of moisture
loss, solvent loss, cross-linking, or other factors. In the
description that follows, the conductive adhesive layer will be
taken to be a hydrogel layer for ease of understanding. The
principles herein may be applied to essentially any type of
electrode that incorporates essentially any type of conductive
adhesive or other layer having electrical properties that degrade
over time.
Those skilled in the art will understand that electrical current
may flow from an electrode's foil layer through the thickness of
the electrode's hydrogel layer. In general, an electrode's hydrogel
layer may exhibit a thickness of 25 to 50 mils. The electrode 150
may further comprise an insulating cover layer, as well as a lead
wire that facilitates coupling to a connector or medical
device.
One electrode 150 may be placed or positioned upon the first
release layer 110 such that the electrode's hydrogel layer covers
one or more of the openings 112 in the release layer 110. Another
electrode 150 may be placed or positioned upon the second release
layer 120 in an analogous manner. Placement of electrodes 150 upon
the release liner 100 in the manner depicted allows the electrodes'
hydrogel layers to contact the moisture-permeable membrane 130 via
the openings 112, 122 in the release layers 110, 120.
Initially, the moisture-permeable membrane 130 may be dry or
essentially moisture free throughout one or more bonding, adhesion,
lamination, and/or attachment procedures performed during release
liner manufacture. In the event that the moisture-permeable
membrane 130 remains dry during release liner manufacture, the
openings 112, 122 in each release layer 110, 120 may ensure that
placement of electrodes 150 upon the release liner 100 results in
moisture transfer from each electrode's hydrogel layer into the
moisture-permeable membrane 130. After a period of time, this
moisture transfer results in low impedance electrical pathways
through the thickness of a given electrode's hydrogel layer, the
moisture-permeable membrane 130, and the thickness of the other
electrode's hydrogel layer in regions defined by the release layer
openings 112, 122.
When the electrodes 150 are coupled to a medical or measuring
device (not shown), the medical device may measure and/or
characterize the electrical pathways between the electrodes'
hydrogel layers and the moisture-permeable membrane 130. As each
electrode's hydrogel layer loses moisture over time, measured
impedance increases. Once the measured impedance has reached or
surpassed a predetermined value, the electrodes may no longer be in
optimal condition, or may be unfit for use. The medical device may
provide an indication of electrode status and/or electrode life
remaining, and/or indicate that electrode replacement is required,
in manners described in detail below.
Placement of electrodes 150 on a release liner 100 having a dry or
essentially dry moisture-permeable membrane 130 contributes to
hydrogel moisture loss. To prevent or minimize such moisture loss,
the moisture-permeable membrane 130 may be prewetted or
premoistened in a variety of manners, such as via placement in a
high-humidity environment (e.g., 50-100% relative humidity) until
it has absorbed sufficient moisture to exhibit a low impedance
value. When residing between the first and second release layers
110, 120 prior to electrode placement, the moisture-permeable
membrane's impedance may be measured or tested via a set of probes
that contact the moisture-permeable membrane 130 through first and
second release layers' openings, in a manner well understood by
those skilled in the art. The moisture-permeable membrane 130 may
alternatively or additionally be moistened using a wet cloth or
sponge, or placed in a liquid bath.
Depending upon embodiment and/or implementation details, the
moisture-permeable membrane 130 may be bonded, adhered, laminated,
and/or otherwise attached to the first release layer 110 but not
the second release layer 120. In such a situation, the adhesion
between the hydrogel of an electrode 150 placed upon the second
release layer 120 and the moisture-permeable membrane 130 will
generally be sufficient to maintain the second release layer 120 in
an appropriate position upon the moisture-permeable membrane
130.
Alternatively, bonding, adhering, laminating, or other
moisture-permeable membrane attachment procedures may be omitted
for both the first and second release layers 110, 120. In such an
embodiment, the moisture-permeable membrane 130 is simply placed or
situated between the first and second release layers 110, 120,
after which electrodes 150 are placed or positioned upon the first
and second release layers 110, 120. In the areas defined by the
first and second release layers' openings 112, 122, the adhesion
between the electrodes' hydrogel layers and the moisture-permeable
membrane 130 may be sufficient to appropriately maintain the
position of each release layer 110, 120 relative to the
moisture-permeable membrane 130. Such an embodiment can simplify
manufacturing processes and reduce production costs.
FIG. 1C is a perspective view of a release liner 170 according to
another embodiment of the invention, and a manner of mounting
electrodes 150 thereupon. Relative to FIG. 1A, like reference
numbers indicate like elements to aid understanding. In one
embodiment, the release liner 170 comprises a single release layer
180 having an opening 182 therein, and a moisture-permeable and/or
moisture-absorbent membrane 130 covering the opening 182. The
moisture permeable membrane 130 may be bonded, adhered, stitched,
and/or otherwise attached to the release layer 180. In an exemplary
embodiment, the moisture-permeable membrane may be heat bonded or
ultrasonically bonded to the release liner 170.
One electrode 150 may be placed or positioned upon the release
layer 180 such that the electrode's hydrogel layer covers the
release layer's opening 182. Another electrode 150 may be placed or
positioned upon the release layer 180 in an analogous manner.
Placement of electrodes 150 upon the release layer 180 allows the
electrodes' hydrogel layers to contact the moisture-permeable
membrane 130 via the release layer's opening 182. In the event that
the moisture-permeable membrane 130 is dry or essentially moisture
free prior to placement of electrodes upon the release layer 180,
moisture transfer from each electrode's hydrogel layer may occur.
After a period of time, such moisture transfer results in a low
impedance electrical pathway between each electrode's hydrogel
layer and the moisture-permeable membrane 130. The moisture
permeable membrane 130 may be premoistened or prewetted as
described above to minimize moisture loss from electrodes' hydrogel
layers.
When the electrodes 150 are coupled to a medical or measuring
device (not shown), the medical device may measure and/or
characterize the electrical pathways between the electrodes'
hydrogel layers and the moisture-permeable membrane 130 in a manner
analogous to that described above.
FIG. 2A is a perspective view of a release liner 200 according to
another embodiment of the invention. Relative to FIG. 1A, like
reference numbers indicate like elements to aid understanding. In
one embodiment, the release liner 200 comprises a foldable release
layer or sheet 210 and a moisture-permeable membrane 130. The
foldable release layer 210 comprises a first mounting or release
portion, region, or segment 220 having at least one opening 222
therein; a second mounting or release portion, region, or segment
230 having at least one opening 232 therein; and a fold region 240.
In one embodiment, the openings 222, 232 in the first and second
mounting portions 220, 230 are formed in corresponding positions
relative to the fold region 240, such that when the foldable
release layer 210 is folded, bent, or doubled about the fold region
240, the openings 222, 232 are essentially coincident.
The foldable release layer 210 may comprise a nonconductive sheet
having non-stick properties, and may be formed using silicon-coated
paper, polyester, polypropylene, polyethylene, and/or other
non-stick materials, in a manner well understood by those skilled
in the art. The openings 222, 232 in the first and second mounting
sections 220, 230 may be cut, stamped, or punched out using
conventional techniques.
The moisture-permeable membrane 130 may comprise a nonconductive,
moisture-permeable and/or moisture-absorbent material, in a manner
analogous to that described above with reference to FIG. 1A. The
moisture-permeable membrane 130 may cover an area less than that of
the first and/or second mounting portions 220, 230, subject to the
requirement that it cover or span openings 222, 232 in each
mounting portion 220, 230 when the foldable release layer 210 is
folded. Depending upon embodiment and/or implementation details,
the moisture-permeable membrane 130 may be adhered, bonded,
laminated, and/or otherwise attached to one, both, or neither of
the first and second mounting sections 220, 230.
The foldable release layer 210 may be folded, bent, or doubled
about the fold region 240 in either direction to surround or encase
one or more portions of the moisture-permeable membrane 130. When
folded in such a manner, the moisture-permeable membrane 130 is
exposed in the regions defined by the openings 222, 232 in the
first and second mounting portions 220, 230.
FIG. 2B is a perspective view of electrodes 150 mounted upon the
release liner 200 of FIG. 2A. One electrode 150 may be positioned
or situated upon an outer surface of the first mounting portion
220, while another electrode 150 may be positioned upon an outer
surface of the second mounting portion 230. The outer surfaces of
the first and second mounting portions 220, 230 together form a
single outer surface of the foldable release layer 210. Thus, both
electrodes 150 are mounted upon the same side or surface of the
foldable release liner 210.
In the description herein, release liner mounting portions 220,
230, such as those described in relation to the release liner 200
of FIGS. 2A and 2B, provide regions or areas upon which electrodes
150 may reside. Electrodes 150 may be readily removed or peeled off
of the mounting portions 220, 230, as the mounting portions 220,
230 comprise non-stick or generally non-stick portions of the
release liner 200.
As with the release liner 100 of FIG. 1A, the moisture-permeable
membrane 139 may remain dry or essentially moisture free during
release liner manufacture or assembly. In such a situation, a low
impedance electrical path may form after electrodes 150 are placed
upon the foldable release layer 210 and the electrodes' hydrogel
layers transfer moisture into the moisture-permeable membrane 130
in the regions defined by the openings 222, 232 in the first and
second mounting portions 220, 230. Alternatively, the
moisture-permeable membrane 130 may be prewetted or premoistened in
the manners described above to help minimize hydrogel moisture
loss.
Once electrodes 150 are mounted or positioned upon the release
liner 200 of FIG. 2A, a medical device to which the electrodes are
coupled may test or characterize the electrical path through one
electrode's hydrogel layer, the moisture-permeable membrane 130,
and the other electrode's hydrogel layer. As a hydrogel layer loses
moisture over time, the medical device may correspondingly measure
increasing impedance levels. An impedance value exceeding a given
threshold may indicate that the electrodes 150 are not optimally
fit for use, or that the electrodes 150 are unsuitable for use and
should be replaced. The medical device may provide an indication of
electrode status and/or remaining electrode life, and/or recommend
electrode replacement, in manners described in detail below.
FIG. 3A is a layered perspective view of a release liner 300
according to another embodiment of the invention. Relative to FIG.
1A, like reference elements indicate like elements to aid
understanding. The release liner 300 may comprise a first release
layer or sheet 310; a second release layer or sheet 320; and a
moisture-permeable membrane 130. In contrast to the release liner
100 of FIG. 1A, openings 112, 122 may not be present in the release
layers 310, 320 of the release liner 300 of FIG. 3A.
Each release layer 310, 320 may comprise a nonconductive sheet
having non-stick properties, and may be implemented using
silicon-coated paper, polyester, polypropylene, polyethylene,
and/or other non-stick materials, in a manner well understood by
those skilled in the art. The moisture-permeable membrane 130 may
comprise a non-conductive, moisture-permeable material in the
manner described above, which resides between the first and second
release layers 310, 320.
Portions of the moisture-permeable membrane reside between the
release layers 310, 320. In one embodiment, the moisture-permeable
membrane 130 overlaps or extends beyond at least one release layer
edge or border. Depending upon embodiment and/or implementation
details, the moisture-permeable membrane 130 may be adhered,
bonded, laminated, and/or otherwise attached to one, both, or
neither release layer 310, 320, in a manner analogous to that
described above with reference to FIG. 1A.
FIG. 3B is a perspective view showing electrodes 150 mounted upon
the release liner 300 of FIG. 3A. In the embodiment shown, the
electrodes' hydrogel layers 150 contact one or more portions of the
moisture-permeable membrane 130 in areas in which the
moisture-permeable membrane 130 overlaps or extends beyond release
layer boundaries. Thus, portions of the electrodes 150 extend
beyond or overlap one or more release layer edges, boundaries,
and/or borders. Therefore, the release layers 310, 320 in such an
embodiment may be appropriately sized or scaled relative to the
size of the electrodes 150 to facilitate such contact.
As shown in FIG. 3B, portions of the electrodes' hydrogel layers
contact the moisture-permeable membrane 130. A low impedance
electrical pathway through the thickness of each electrode's
hydrogel layer and the moisture-permeable membrane 130 may arise
following moisture transfer from hydrogel layers to the
moisture-permeable membrane 130. Alternatively, the
moisture-permeable membrane 130 may be prewetted or premoistened to
facilitate a low impedance pathway while minimizing hydrogel
moisture loss. As with the release liners 100, 200 described above,
when electrodes 150 mounted upon the release liner 300 of FIG. 3A
are coupled to a medical device, the medical device may measure
increasing impedance levels over time as the electrodes' hydrogel
layers lose moisture. Impedance levels greater than a given
threshold or beyond a given range may indicate one or more
electrodes 150 are non-optimal or unfit for use. A medical device
may provide an indication of electrode condition in a variety of
manners described in detail below.
In a manner analogous to that for the embodiments shown in FIG. 2A
and FIG. 3A, a foldable release layer that lacks openings (not
shown) may partially enclose or envelop a moisture-permeable
membrane 130, such that the moisture-permeable membrane 130 extends
beyond one or more edges of the foldable release layer when so
enclosed. When an inner surface of such a foldable release layer
surrounds or encases portions of a moisture-permeable membrane 130,
electrodes 150 may be positioned on a common outer surface of the
foldable release layer such that the electrodes' hydrogel layers
contact exposed portions of the moisture-permeable membrane 130.
This hydrogel to moisture-permeable membrane to hydrogel contact
facilitates transfer of electrical signals between electrodes 150.
As in embodiments described above, the moisture-permeable membrane
130 in such an embodiment may or may not be adhered, laminated, or
otherwise attached to one or more segments or regions of the
foldable release layer. Additionally, the moisture-permeable
membrane 130 may be prewetted or premoistened to minimize moisture
loss from each electrode's hydrogel layer.
FIG. 4 is a perspective view of a release liner and electrode
package 400 according to an embodiment of the invention. The
release liner and electrode package 400 may comprise a release
liner 404, electrodes 150 mounted thereupon, and a rigid cartridge
408 in which a release liner 410 and mounted electrodes 150 may be
stored prior to use. The release liner 404 may comprise a release
layer 410 having an opening 422 therein. The release layer 410 may
comprise a nonconductive, non-stick material such as those
described above, and the opening 422 may be cut, stamped, or
punched out of the release layer 410 via conventional techniques.
One electrode 150 may be mounted or positioned upon one side of the
release layer 410, while another electrode 150 may be mounted
another side of the release layer 410, such that each electrode's
hydrogel layer covers the release layer's opening 422. Such
electrode mounting may result in hydrogel layer to hydrogel layer
contact, thereby facilitating electrical communication between
electrodes 150. In an alternate embodiment, the release layer 410
may include multiple openings 422, where mounted electrodes 150 may
cover some or all of such openings 422.
The rigid cartridge 408 may comprise a housing or tray 450, a
removable lid 452, and an electrical interface 460. The tray 450
and removable lid 452 may comprise plastic or another conventional
material, and may store the mounted electrodes 150. The electrical
interface 460 may comprise a connector that facilitates electrical
coupling of the electrodes 150 to a medical device. In one
embodiment, the rigid cartridge 408 may be implemented in a manner
described in U.S. patent application Ser. No. 09/746,123, entitled
CARTRIDGE FOR STORING AN ELECTRODE PAD AND METHODS FOR USING AND
MAKING THE CARTRIDGE, filed on Dec. 22, 2000, which is incorporated
by reference.
The rigid cartridge 408 facilitates high-reliability sealing of
mounted electrodes 150 within an environment that may be
characterized by well-defined conditions. In particular, via a
conventional technique such as injection molding, the electrical
interface 460 may be molded into the tray 450 such that when the
lid 452 is sealed upon the tray 450, moisture transfer into or out
of the rigid cartridge 408 is minimized, eliminated, or essentially
eliminated. Storage of unused electrodes 150 within the rigid
cartridge 408 may therefore extend electrode shelf life by slowing
and/or minimizing moisture loss from the electrodes' hydrogel
layers. The rigid cartridge 408 may additionally protect the
electrodes 150 contained therein. Such protection may be necessary
in the event that the medical device comprises an AED that is
deployed or transported in real-world conditions, such as within
law enforcement or rescue vehicles.
When electrodes 150 that have been mounted upon the release liner
404 and sealed within the rigid cartridge 408 are coupled to a
medical device, the medical device may test and/or characterize the
electrical path between the electrical interface 460, a given
electrode's lead wire, the given electrode's conductive foil layer,
the given electrode's hydrogel layer, through the release layer's
opening 422, and through the other electrode's hydrogel layer,
conductive foil layer, and lead wire back to the electrical
interface 460. In the event that a short or open circuit condition
exists, the electrical interface 460, a lead wire, and/or possibly
one or both electrodes 150 may be damaged or defective. In the
event that the medical device measures an impedance level or value
that exceeds a predetermined threshold or range, the electrodes 150
may be non-optimal or unfit for use. The medical device may provide
one or more indications of the condition of the aforementioned
electrical path in a variety of manners, as described in detail
below.
FIG. 5A is a perspective view of a release liner 500 according to
another embodiment of the invention. The release liner 500 may
comprise a single release layer or sheet 510; and a conductive
strip 550 positioned, mounted, and/or affixed thereupon. In one
embodiment, the release layer 510 may be characterized by a
mounting surface 512, a length 514, and a width 516. The release
layer 510 comprises a nonconductive sheet having non-stick
properties, and may be implemented or fabricated using materials
such as those described above with respect to other release liner
embodiments. The conductive strip 550 may be characterized by a
length 554 and a width 556, and comprises an electrically
conductive material such as a metal foil (e.g., Aluminum or Tin),
or an impregnated or sprayed-on metal layer.
In one embodiment, the conductive strip 550 resides upon the
release layer's mounting surface 512. The conductive strip 550 may
exhibit a wide range of lengths 554 and/or widths 556. In the
embodiment shown, the conductive strip's length 554 is
approximately equal to the length 514 of the release layer 510,
while the conductive strip's width 556 spans a portion of the
release layer's width 516. In general, the conductive strip 550
should be dimensioned to ensure 1) a reliable electrical pathway
from one electrode 150 to another exists when the electrodes 150
are placed or mounted in a side-by-side manner upon the release
layer 510; and 2) a sufficient portion of any given electrode's
hydrogel layer resides upon the non-stick release layer 510,
thereby facilitating easy removal of electrodes 150 from the
release layer 510. Those skilled in the art will understand that
the conductive strip's dimensions 554, 556 may be impacted by cost
and/or manufacturability considerations. Those skilled in the art
will further understand that the release layer 510 and/or the
conductive strip 550 need not be strictly rectangular, and/or may
include one or more non-rectangular portions.
FIG. 5B is a perspective view of electrodes 150 mounted upon the
release liner 500 of FIG. 5A. Electrodes 150 may be positioned or
mounted upon the mounting surface 512 in a side-by-side manner,
such that a portion of each electrode's hydrogel layer electrically
contacts the conductive strip 550. Thus, the conductive strip 550
facilitates current flow between electrodes 150 mounted upon the
release liner 500. When electrodes 150 mounted upon the release
liner 500 are coupled to a medical device, the medical device may
electrically test or characterize the electrical path from one
electrode 150 to the conductive strip 550 to another electrode 150.
A short or open circuit condition may imply a problem with a lead
wire, a connector, one or more electrodes 150, and/or the
conductive strip 550. As electrodes' hydrogel layers lose moisture,
the impedance that a medical device may measure along the
aforementioned electrical path may increase, indicating that one or
more electrodes 150 are non-optimal or unfit for use. As described
in detail below, the medical device may perform various operations
and/or provide indications of electrode fitness following
measurement of an impedance associated with electrodes 150 mounted
upon a release liner 500.
FIG. 6A is a perspective view of another embodiment of a release
liner 600 according to an embodiment of the invention. The release
liner 600 comprises a foldable release layer or sheet 610 and a
conductive strip 650. The foldable release layer 610 may be
characterized by an outer or mounting surface 612; a length 614; a
width 616; a first mounting or release portion, region, or segment
620; a second mounting or release portion, region, or segment 630;
and a fold region 640. The foldable release layer 610 may be
fabricated using a nonconductive, non-stick material in manners
previously described. The conductive strip 650 be characterized by
a length 654 and a width 656, and may comprise a material such as
Aluminum or Tin. The conductive strip 650 may be positioned,
mounted, and/or affixed upon the release layer's mounting surface
612.
FIG. 6B is a perspective view of electrodes 150 mounted upon the
release liner 600 of FIG. 6A. The foldable release layer 610 may be
bent, folded, or doubled about the fold region 640 in either
direction (i.e., such that the conductive strip 650 is exposed, or
such that the conductive strip 650 is enclosed by the release layer
610 and is therefore unexposed), thereby reducing or minimizing the
amount of space the release liner 610 and mounted electrodes 150
occupy. Electrodes 150 may be mounted in a side-by-side manner upon
the foldable release layer's mounting surface 612, such that one
electrode 150 resides upon the first mounting portion 620 and
another electrode resides upon the second mounting portion 630.
When mounted in such a manner, a portion of each electrode's
hydrogel layer electrically contacts the conductive strip 650.
Thus, electrical current may flow from one electrode 150 to another
via the conductive strip 650. As with the release liner of FIGS. 5A
and 5B, a medical device to which the mounted electrodes 150 are
coupled may test or characterize the electrical path between one
electrode 150, the conductive strip 650, and another electrode 150.
The medical device may provide an indication of electrode fitness
based upon such electrical path characterization in manners
described below. Those skilled in the art will recognize that the
release layer 610 and/or the conductive strip 650 may exhibit a
variety of dimensional characteristics, in a manner analogous to
that described above with respect to FIG. 5A.
FIG. 7 is a perspective view of a release liner 700 according to
another embodiment of the invention, and a manner of mounting
electrodes 150 thereupon. In the embodiment shown, the release
liner 700 comprises a conductive strip or band 750 mounted upon a
single release layer or sheet 710 having a first and a second
indented portion or region 712, 714. The release layer 710
comprises a nonconductive, non-stick material constructed in a
manner analogous to release layers described above. The indented
portions 712,714 may be cut, stamped, or punched out of the release
layer 710 during manufacture. The conductive band 750 comprises an
electrically conductive material such as a metal.
The conductive band 750 may be positioned, mounted, and/or affixed
upon or around the release layer 710 within boundaries defined by
the release layer's first and second indented portions 712, 714.
Thus, the conductive band 750 may wrap around the release layer,
held in position by borders or edges defined by the release liner's
indented portions 712, 714. In an alternate embodiment, the
conductive band 750 may comprise a first and a second conductive
band, which may overlap.
One electrode 150 may be mounted or positioned upon a first side of
the release layer 710, while another electrode 150 may be mounted
or positioned upon a second side of the release layer 710. The
conductive band 750 facilitates electrical contact between the
electrodes' hydrogel layers. Thus, a medical device to which the
mounted electrodes 150 are coupled may test or characterize the
electrical path through one electrode 150, the conductive band 750,
and the other electrode 150. Those skilled in the art will
understand that in alternate embodiments, the release layer may
have one or no indented portion 712, 714, and/or the conductive
band 750 may only partially wrap around the release layer 710. In
such an embodiment, the conductive band 750 may be affixed or
adhered to the release layer 710 via conventional techniques. Those
skilled in the art will further understand that in an alternate
embodiment, the indented portions 712, 714 may be replaced with
protruding portions.
FIG. 8A is a layered perspective view of a release liner 800
according to another embodiment of the invention. The release liner
800 comprises a release layer or sheet 810 and a backing layer 860.
The release layer 810 may comprise a nonconductive, non-stick sheet
having a front or electrode mounting surface 812; a rear or backing
surface 814; a first opening 822; and a second opening 832. The
release layer 810 may be manufactured using materials such as those
described above, and the openings 822, 832 therein may be cut,
punched, and/or stamped out of such materials via conventional
techniques.
The backing layer 860 may comprise an electrically conductive layer
positioned, mounted, or affixed upon the release layer's rear
surface 814. When the backing layer 860 is mounted or positioned
upon the release layer's rear surface 814, the nonconductive
release layer 810 covers the backing layer 860 except in areas
defined by the release layer's openings 822, 832. Those skilled in
the art will understand that the backing layer 860 need not be the
same size as the release layer 810, as long as the backing layer
860 covers the release layer's openings 822, 832. The backing layer
860 may comprise, for example, a metal or foil. The foil may itself
be mounted upon or affixed to a substrate or carrier material, such
as paper. Alternatively, the backing layer 860 may comprise a
conductive adhesive layer, such as a layer of hydrogel, which may
reside upon a substrate or carrier material such as paper or
plastic.
FIG. 8B is a perspective view of electrodes 150 mounted upon the
release liner 800 of FIG. 8A. Electrodes 150 may be mounted upon
the release layer's mounting surface 812 in a side-by-side manner,
such that one electrode 150 covers the release layer's first
opening 822, and another electrode 150 covers the release layer's
second opening 832. When an electrode 150 covers an opening in the
release layer 810, the electrode's hydrogel layer contacts the
conductive backing layer 860 through the opening 822, 832. Thus,
the openings 822, 832 facilitate current flow between the
electrode's hydrogel layer and the backing layer 860. Hence, when
electrodes 150 reside upon the release liner 800, electrical
current may flow from an electrode 150 covering the first opening
822 into the backing layer 860, and into an electrode 150 covering
the second opening 832.
In an alternate embodiment, the release layer 810 may comprise two
or more separate sheets or electrode mounting or release portions
rather than a single sheet. Each mounting portion may include an
opening. Mounting portions upon which electrodes 150 may reside may
be positioned upon the conductive backing layer 860 in a variety of
manners (electrodes 150 may be positioned upon mounting portions
either before or after such mounting portions are situated upon the
conductive backing layer 860). In conjunction with the conductive
backing layer 860, the openings in the mounting portions facilitate
electrical communication or signal exchange between electrodes
150.
In release liner embodiments previously described with reference to
FIGS. 1 through 7, electrical pathways are defined relative to the
thickness of hydrogel layers. Impedance values measured through the
thickness of one or more hydrogel layers, however, may coincide
with or fall within the same range as impedance values associated
with a patient, for example, 50 to 250 Ohms. As a result, a medical
device may be unable to determine whether electrodes 150 are
attached to a patient's body or residing upon a release liner 100,
200, 300, 400. Although impedance values measured through hydrogel
layer thickness increase as hydrogel layers dry out, even such
increased impedance values are likely to overlap the patient
impedance range.
Relative to the release liner of FIGS. 8A and 8B, when the backing
layer's conductive medium comprises a layer of hydrogel, electrical
current may flow through a length of hydrogel defined by a distance
between the release layer's first and second openings 822, 832. The
average impedance through the length of a hydrogel layer is much
larger than that through the hydrogel layer's thickness. For
example, at 70% relative humidity, the average impedance per square
through a hydrogel layer's length may be approximately 2 kOhm. This
impedance is greater than the patient impedance range by an amount
sufficient to ensure that a measured impedance value indicates that
electrodes 150 are mounted upon the release liner 800 rather than a
patient's body. In addition to the release liner 800 embodiments
shown in FIGS. 8A and 8B, other release liner structures that
advantageously establish current paths through a length of an
electrode's hydrogel layer are described in detail below with
reference to FIGS. 10A, 10B, 11, and 12.
A medical device to which electrodes 150 mounted upon as the
release liner 800 of FIG. BA are coupled may test or characterize
the electrical pathway defined by one electrode 150, the backing
layer's conductive medium exposed within and extending between the
release layer's first and second openings 822, 832, and another
electrode 150. A short or open circuit condition may imply a
problem with one or more electrodes 150. As electrodes' hydrogel
layers lose moisture, the impedance of the aforementioned
electrical path will increase. The impedance of this electrical
path will also increase as hydrogel used in the backing layer 860
loses moisture. Upon measuring an impedance level that exceeds a
given threshold, the medical device may indicate that the
electrodes 150 are non-optimal or no longer fit for use, as further
detailed below.
Different hydrogel formulations, as well as identically formulated
hydrogels originating from different manufacturing hatches, may
exhibit different moisture absorption and loss characteristics.
Referring again to FIGS. 8A and 8B, in the event that the backing
layer 860 comprises a layer of hydrogel originating from a
different formulation or manufacturing batch than that of the
electrodes 150 mounted upon the release liner 800, the electrodes'
hydrogel layers may donate moisture to or receive moisture from the
backing layer's hydrogel. This, in turn, may cause the electrodes'
hydrogel layers to undesirably swell or prematurely dry out.
If the backing layer's hydrogel arises from the same manufacturing
batch as that of the electrodes 150, the backing layer's hydrogel
will neither donate moisture to or receive moisture from the
electrodes' hydrogel layers. Rather, the backing layer's hydrogel
may lose moisture to the inside of a package at a rate that is
identical or essentially identical to that at which the electrodes
150 lose moisture. The backing layer 860 may therefore provide a
moisture reservoir to a package, advantageously enhancing the
lifetime of electrodes 150 within the package.
FIG. 9A is a perspective view of a release liner 900 according to
another embodiment of the invention. The release liner 900
comprises a foldable release layer or sheet 910 and a conductive
backing layer 960. The foldable release layer 910 comprises a
nonconductive, non-stick sheet that includes an electrode mounting
surface 912; a backing surface 914; a first mounting or release
portion 920 having a first opening 922; a second mounting or
release portion 930 having a second opening 932; and a fold region
940. The foldable release layer 910 may be manufactured from
conventional nonconductive, non-stick materials such as those
previously described, where the first and second openings 922, 932
may be cut, punched, or stamped out of such materials in
conventional manners.
The backing layer 960 may comprise a conductive material such as a
layer of metal or hydrogel. The foldable release layer 910 may be
folded, bent, or doubled in either direction about its fold region
940 such that its backing surface 914 surrounds or encases portions
of the backing layer 960, thereby forming a release layer-backing
layer-release layer assembly in which the backing layer 960 is
exposed in regions defined by the release layer's first and second
openings 922, 932.
FIG. 9B is a perspective view showing electrodes 150 mounted upon
the release liner 900 of FIG. 9A. One electrode 150 may be mounted
upon the release layer's first mounting portion 920, while another
electrode 150 may be mounted upon the release layer's second
mounting portion 930. Thus, the electrodes 150 both reside upon the
release layer's mounting surface 912.
A medical device to which the electrodes 150 are coupled may
electrically test or characterize the electrical path through one
electrode's hydrogel layer, the release layer's first opening 922,
the conductive medium of the backing layer 960, the release layer's
second opening 932, and the other electrode's hydrogel layer. A
short or open circuit condition may imply a problem with one or
more electrodes 150. As electrodes' hydrogel layers, as well as a
hydrogel layer within the conductive backing layer 960 lose
moisture, the impedance of the aforementioned electrical path will
increase. Upon measuring an impedance level that exceeds a given
threshold, the medical device may indicate that the electrodes 150
are non-optimal or no longer fit for use, as further described in
detail below.
As described above, release liner structures facilitating electrode
characterization via electrical current flow through a given length
of hydrogel may enable a medical device to accurately and/or
consistently determine whether electrodes 150 are mounted upon the
release liner structure or a patient's body. Additional release
liner structures that facilitate electrical characterization of
electrodes 150 in this manner are described in detail
hereafter.
FIG. 10A is a layered plan view of a release liner 1000 according
to another embodiment of the invention. In one embodiment, the
release liner 1000 comprises a first release layer or sheet 1020, a
second release layer or sheet 1030, and an intervening conductive
adhesive layer or hydrogel layer 1070. Each release layer 1020,
1030 comprises a nonconductive, non-stick material that may be
implemented or fabricated using a variety of conventional
materials, such as those described above. The first release layer
1020 includes an opening 1022 that is offset or shifted relative to
a center point 1024. Similarly, the second release layer 1030
includes an opening 1032 that is offset or shifted relative to a
center point 1034.
The first and second release layers 1020, 1030 may be positioned to
cover or encase portions of the hydrogel layer 1070, such that the
first and second openings 1022, 1032 are non-coincident. In such an
alignment, the first and second openings 1022, 1032 are offset with
respect to each other relative to any given release layer's center
point 1024, 1034. When covering or encasing the hydrogel layer
1070, the first and second release layers 1020, 1030 may be
adhered, laminated, or attached together. Alternatively, adhesion
between the release liner's hydrogel layer 1070 and electrodes'
hydrogel layers may be sufficient to hold the release liner 1000
together.
FIG. 10B is a perspective view of electrodes 150 mounted upon the
release liner of FIG. 10A. One electrode 150 resides upon the first
release layer 1020, while another electrode 150 resides upon the
second release layer 1030. A medical device to which the electrodes
150 are coupled may test or characterize an electrical path through
the thickness of one electrode's hydrogel layer in the area spanned
by the first opening 1022; the length of the release liner's
hydrogel layer 1070 spanning a distance between the first and
second openings 1022, 1032; and the thickness of another
electrode's hydrogel layer in the area spanned by the second
opening 1032. Since current flows through an electrical path that
includes a length of hydrogel significantly larger than the
thickness of the electrodes' hydrogel layers or the release liner's
hydrogel layer 1070, the impedance associated with this electrical
path will be significantly greater than typical patient impedance
ranges.
The medical device may measure a short or open circuit condition,
which may imply dysfunctional or nonoperational electrodes 150. As
the electrodes' hydrogel layers lose moisture, or as the release
liner's hydrogel layer 1070 loses moisture, the impedance
associated with the electrical path in this embodiment will
increase. The medical device may subsequently determine that the
electrodes 150 are non-optimal or unfit for use, and provide an
indication of such in manners detailed below.
FIG. 11A is a perspective view of a release liner 1100 according to
another embodiment of the invention. In one embodiment, the release
liner 1100 comprises a foldable release layer or sheet 1110 and a
hydrogel layer 1170. The foldable release layer 1110 may comprise a
nonconductive, non-stick sheet that includes an electrode mounting
surface 1112; a rear surface 1114; a first mounting or release
portion 1120 having a first opening 1122 offset relative to a
midpoint 1124 within the first mounting portion 1120; a second
mounting or release portion 1130 having a second opening 1132
offset relative to a midpoint within the second mounting portion
1130; and a fold region 1140. The foldable release layer 1110 may
be fabricated from conventional materials such as those described
above, where the first and second openings 1122, 1132 may be cut,
punched, and/or stamped out in conventional manners. In an
alternate embodiment, the first and/or second openings 1122, 1132
may respectively comprise a first and/or a second set of
openings.
The foldable release layer 1110 may be folded, bent, or doubled
about its fold region 1140 such that its rear surface 1114
surrounds or encases portions of the hydrogel layer 1170. The
hydrogel layer 1170 may be exposed via the first and second
openings 1122, 1132 within the first and second mounting portions
1120, 1130, respectively. When the release layer 1110 is folded and
encases the hydrogel layer 1170, the first and second openings
1122, 1132 are non-coincident or offset relative to each other,
such that they are separated by a predetermined or as-manufactured
length or distance. This separation distance ensures that when
electrodes 150 are mounted upon the release liner 1100 and coupled
to a medical device, electrical current may travel through a given
length of the hydrogel layer 1170, where this length is
significantly greater than the hydrogel layer's thickness. As a
result, the electrical path provided by the release liner of FIG.
11A may exhibit an impedance level significantly greater than
typical patient transthoracic impedance levels.
FIG. 11B is a perspective view of electrodes 150 mounted upon the
release liner 1100 of FIG. 11A. Electrodes 150 mounted upon this
release liner 1100 may be tested and/or characterized in manners
analogous to those described above for other release liner
embodiments.
Electrodes themselves may be designed such that current flow within
the electrode may occur through a given length of the electrode's
hydrogel layer when the electrodes are mounted upon a release
liner. Various electrode embodiments that may be characterized by
current flow through portions of a hydrogel layer's length are
described in detail hereafter.
FIG. 12A is a cross sectional view of an electrode 1200 according
to an embodiment of the invention. FIG. 12B is a plan view of the
electrode 1200 of FIG. 12A. In the embodiment shown, the electrode
1200 comprises a conductive adhesive material, gel layer, or
hydrogel layer 1210; a conductive or foil layer 1220 having at
least one opening or void 1222 therein; an insulating or dielectric
layer 1230; and a lead wire 1240. Each element 1210, 1220, 1230,
1240 within the electrode 1200 may be implemented using
conventional materials. The hydrogel layer 1210 interfaces the
electrode 1200 to a patient's body or a release liner. The foil
layer 1220 resides upon the hydrogel layer 1210, and the insulating
layer 1230 resides upon the foil layer 1220. Finally, the lead wire
1240 is coupled to the foil layer 1220, and may be covered with an
insulating material in a manner well understood by those skilled in
the art.
Each void 1222 may be cut, stamped, or punched out of the
conductive foil layer 1220 in a conventional manner. Furthermore,
each void 1222 may be positioned at a given location that
corresponds to an area in which electrical contact with a
conductive region, area, section, and/or element of an appropriate
type of release liner is desired. The presence of a void 1222 in
the foil layer 1220 may affect the manner in which electrical
current may flow through or within the electrode 1200 when the
electrode 1200 is mounted upon a patient's body.
FIG. 13A is a graph of exemplary current density relative to
lateral position for a conventional electrode mounted upon a
patient's body. Those skilled in the art will understand that
current flows more easily between an electrode and a patient's body
near the electrode's edges. As one moves from an interior region
toward an outer edge or border of the electrode's foil layer,
current density increases and peaks.
FIG. 13B is a graph showing exemplary shock current density
relative to lateral position beneath elements of an electrode 1200
of FIG. 12A when the electrode 1200 is mounted upon a patient's
body. Within a region defined by a void 1222, current density drops
to a minimum value relative to its value beneath the foil layer
1220. At a foil layer edge or boundary, current density exhibits a
peak. The presence of a void 1222 provides an additional foil layer
edge or boundary at which a current density peak may occur. Those
skilled in the art will understand that as a result of such current
density peaks, the presence of one or more properly positioned
voids 1222 in the foil layer 1220 need not increase, and may
decrease, the effective shock impedance of the electrode 1200.
Those skilled in the art will thus understand that the areas under
the curves shown in FIGS. 13A and 13B may be identical or
essentially identical. Alternatively, the area under the curve
shown in FIG. 13B may be greater than that under the curve shown in
FIG. 13A.
The presence of a void 1222 in an electrode's foil layer 1220 may
also affect the manner in which electrical current may flow through
or within the electrode 1200 when the electrode 1200 is mounted
upon a release liner. FIG. 14A is a perspective view of two voided
electrodes 1200 of FIG. 12A mounted upon a release liner 1400
according to another embodiment of the invention. FIG. 14B is a
cross sectional view of the voided electrodes 1200 mounted upon the
release liner 1400 of FIG. 14A. The release liner 1400 may comprise
a nonconductive, nonstick release layer 1410 having an opening 1422
therein. The release layer 1410 may be implemented using
conventional materials such as those previously described, and the
opening 1422 may be cut, stamped, or punched out of the release
layer 1410 via conventional techniques.
The release layer's opening 1422 may be smaller than the voids 1222
in the electrodes' conductive foil layers 1220. One voided
electrode 1200 may be mounted upon one side of the release layer
1410, while another electrode 1200 may be mounted upon the release
layer's opposite side, such that the void 1222 in each electrode's
conductive foil layer 1220 surrounds the release layer's opening
1422. The release layer's opening 1422 facilitates hydrogel layer
1210 to hydrogel layer 1210 contact within areas defined by each
electrode's void 1222.
The presence of a void 1222 may ensure that electrical current flow
involves a hydrogel layer's length and/or width in addition to the
hydrogel layer's thickness. That is, current flow may include or be
decomposed into lateral or transverse components that are parallel
or essentially parallel to a plane defined by the interface between
the electrode's hydrogel layer 1210 and the conductive foil layer
1220. When voided electrodes 1200 mounted upon a release liner 1400
are coupled to a medical or measuring device, electrical current
may flow from an edge of a given electrode's conductive foil layer
1220 that defines a void's boundary or border, through the given
electrode's hydrogel layer 1210 and to the release liner opening
1422 along a path that includes transverse or lateral components,
and into and through the other electrode 1200 in a corresponding
manner. In other words, electrical current may flow from one
electrode 1200 to another along a current path that includes
transverse or lateral components through each electrode's hydrogel
layer 1210. Exemplary current paths that include transverse or
lateral components are indicated in FIG. 14B via curved arrows.
Electrical current may travel a greater distance along a current
path that involves transverse components than along a current path
defined solely by a hydrogel layer's thickness. Also, bulk
impedance values may be larger and/or more readily measured over a
longer current path than a shorter current path. As a result, an
electrical path that includes or involves transverse components or
a length of an electrode's hydrogel layer 1210 between a foil
layer/void boundary and a release liner opening 1422 may be
characterized by a higher impedance than an electrical path defined
by a hydrogel layer's thickness. This, in turn, may ensure that the
impedance level corresponding to electrodes 1200 appropriately
mounted or positioned upon a release liner 1400 is greater than
typical patient impedance levels. Additionally, electrodes 1200
that may be characterized via measurements involving transverse
current components (e.g., electrodes 1200 that incorporate one or
more voids 1222) may exhibit enhanced response to impedance changes
resulting from hydrogel layer moisture loss.
As a result of the foregoing, electrodes 1200 having one or more
voids 1222 incorporated therein and which are mounted upon a
release liner 1400 may exhibit a packaged or mounted impedance
level that is greater or significantly greater than typical patient
impedance levels, even for electrodes 1200 that are new,
essentially new, and/or in excellent, good, and/or acceptable
operating condition. As the condition of one or more such
electrodes 1200 deteriorates over time, a packaged impedance
measurement may provide a particularly sensitive indication of
deterioration, as a corresponding measured impedance may exhibit a
large increase over time in response to such deterioration.
The size or area associated with an electrode's void 1222 relative
to 1) the size, area, and/or position of a release liner's opening
1422; and/or 2) the thickness of the electrode's hydrogel layer
1210 may affect or determine an extent to which transverse
components contribute to electrical current flow. Larger transverse
contributions to electrical current flow result in larger measured
impedance values. A hydrogel layer 1210 may be characterized by a
thickness H. A boundary or edge separation distance between a void
1222 and a release liner opening 1422 may be characterized by a
distance L, as shown in FIG. 14B. In one embodiment, to ensure
sufficient transverse or lateral contributions to electrical
current flow between electrodes 1200 mounted upon a release liner
1400, the ratio L/H should be significantly greater than 1.
The area associated with a given void 1222 may be larger than that
associated with a release liner opening 1422 over which the void
1222 is positioned. In an exemplary embodiment, a void 1222 may
have an area approximately 300% greater than a release liner
opening 1422. Such an area relationship may aid manufacturability
by providing a positional tolerance during electrode mounting
procedures. Those skilled in the art will understand that the
voided electrodes 1200 may have differently sized and/or
differently shaped voids, which may further influence the manner in
which electrical current may laterally flow through portions of a
hydrogel layer. In addition, one or more voids may be present in
one electrode 1200, while another electrode lacks voids.
A medical device to which voided electrodes 1200 mounted to a
release liner 1400 are coupled may reliably determine whether the
voided electrodes 1200 are mounted upon the release liner 1400 or a
patient's body. A medical or measuring device may determine that a
short or open circuit condition exists along or within the
aforementioned electrical path, in which case the electrical path
and/or one or more electrodes 1200 may be damaged or defective. The
medical or measuring device may also determine an electrode
condition or fitness level based upon an impedance measurement. As
indicated above, impedance measurements involving transverse or
lateral current paths may be particularly sensitive to changes in
hydrogel layer moisture content. In the event that an impedance
measurement result exceeds a given threshold or range, the medical
or measuring device may provide an indication that the electrodes
1200 may be non-optimal or unfit for use, in manners described in
detail below.
FIG. 15 is a plan view of the electrode 1200 of FIG. 12A and a
conventional electrode 150 mounted upon the release liner of FIG.
8A. The voided electrode 1200 is mounted or oriented such that a
void 1222 therein surrounds the release liner's first opening 822,
while the conventional electrode 150 is positioned such that it
covers or overlaps the release liner's second opening 832. Those
skilled in the art will understand that the conventional electrode
150 may be replaced with a voided electrode 1200, 1250 in an
alternate embodiment. In an embodiment having an electrode 1250
with multiple voids 1222, 1224, the release liner 800 may include
an appropriate set of openings corresponding to each such void
1222, 1224.
A medical device to which the electrodes 1200, 150 are coupled may
test or characterize the electrical path laterally through a length
of the voided electrode's hydrogel layer 1210, through the release
liner's conductive backing layer 860, and through the hydrogel
thickness within the conventional electrode 150. A measured
impedance level that exceeds a given threshold and/or falls outside
a particular range may indicate that one or more electrodes 1200,
150 mounted upon the release liner 800 are non-optimal or unfit for
use. The medical device may provide one or more indications of
electrode condition or fitness in manners described in detail
below.
As described above, any given void 1222, 1224 may affect the manner
in which current flow occurs through and/or within an electrode
1200, 1250. The presence of a void 1222, 1224 may result in
transverse or lateral current flow through a portion of an
electrode's hydrogel layer 1210. For example, when an electrode
1200 is mounted upon a nonconductive release layer such that a void
1222, 1224 surrounds a release layer opening that facilitates
access to a conductive medium, a direct electrical path from a foil
layer 1220 through the thickness of the hydrogel layer 1210 to the
conductive medium may not exist. As a result, transverse current
flow may occur. As previously indicated, an electrode 1200 may
include multiple voids 1222, which may be shaped and/or positioned
in a variety of manners relative to each other.
FIG. 12C is a plan view of an electrode 1250 according to another
embodiment of the invention. Relative to FIGS. 12A and 12B, like
reference numbers indicate like elements for ease of understanding.
In the embodiment shown, the electrode 1250 comprises a hydrogel
layer 1210; a conductive or foil layer 1220 having a void 1222 and
a recess 1224; a dielectric layer 1230; and a lead wire 1240. Each
of the hydrogel layer 1210, the foil layer 1220, the dielectric
layer 1230, and the lead wire 1240 may be implemented using
conventional materials.
The void 1222 may comprise a generally circular, elliptical, or
otherwise shaped opening that is generally disposed or positioned
within a central region or area of the foil layer 1220. The recess
1224 may comprise an opening and/or open region that extends to an
outer edge or boundary of the foil layer 1220. Each void and/or
recess 1222, 1224 may be positioned over a corresponding opening in
a release liner. In accordance with various embodiments, the voids
1222 and/or recesses 1224 detailed above may be shaped and/or
positioned differently. Additionally, any given electrode
embodiment may have additional or fewer voids 1222 and/or recesses
1224.
The presence of an insulating material may affect electrical
current flow between electrodes mounted upon a release liner in a
manner that is identical or essentially identical to that described
above relative to voids 1222, as described in detail hereafter.
FIG. 12D is a cross sectional view of an electrode 1260 according
to another embodiment of the invention. FIG. 12E is a plan view of
the electrode 1260 of FIG. 12D. Relative to FIGS. 12A, 12B, and
12C, like reference numbers indicate like elements. The electrode
1260 may comprise a hydrogel layer 1210; a conductive or foil layer
1220; an insulating or dielectric layer 1230; and a lead wire 1240,
each of which may be implemented using conventional materials. The
electrode 1260 further comprises a set of insulating or
nonconductive internal patches or swatches 1226. While FIGS. 12D
and 12E show an embodiment that includes a single internal swatch
1226, additional internal swatches 1226 may be present in alternate
embodiments. Those skilled in the art will also understand that in
alternate embodiments, an electrode may include one or more voids
1222, 1224 instead of or in addition to one or more internal
swatches 1226.
Any given internal swatch 1226 may comprise an insulating material
such as polyethylene. Each internal swatch 1226 may reside between
the hydrogel layer 1210 and the conductive foil layer 1220. An
internal swatch 1226 may be positioned at a given location that
corresponds to an area in which electrical contact with a
conductive region, area, section, and/or element of a release liner
or another electrode is desired. Because the internal swatch 1226
is nonconductive, its presence affects the manner in which current
may flow through and/or within the electrode 1260, in a manner
analogous to that described above for voids 1222.
FIG. 16 is a plan view showing electrodes 1260 of FIG. 12D mounted
upon the release liner 800 of FIG. 8A. One electrode 1260 may be
positioned or oriented such that its internal swatch 1226 overlaps
or surrounds the release liner's first opening 822, while another
electrode 1260 may be positioned or mounted such that its internal
swatch 1226 overlaps the release liner's second opening 832. A
direct electrical path from any given electrode's foil layer 1220
through the thickness of the electrode's hydrogel layer 1210 and
into the release liner's conductive backing layer 860 via the first
or second opening 822, 832 may not exist due to the presence of the
internal swatches 1226. Thus, the presence of an internal swatch
1226 may result in lateral or transverse current flow through a
length of an electrode's hydrogel layer 1210. Such current flow
originates from a foil layer 1220 along a boundary or interface
defined by an intersection of the foil layer's area and the area of
the internal swatch 1226, and laterally extends to or past a
boundary or interface defined by the area of an appropriate release
liner opening 822, 832. Those skilled in the art will understand
that electrodes 1260 incorporating one or more internal swatches
1226 therein may be mounted upon other release liner types, such as
the release liner 1400 of FIG. 14A.
A medical device to which the electrodes 1260 are coupled may test
or characterize the electrical path through a length of each
electrode's hydrogel layer 1210 and through the release liner's
conductive backing layer 860 via the first and second release liner
openings 822, 832. A measured impedance level that exceeds a given
threshold and/or falls outside a particular range may indicate that
one or more electrodes 1260 mounted upon the release liner 800 are
non-optimal or unfit for use. The medical device may provide one or
more indications of electrode condition or fitness in manners
described in detail below.
Those skilled in the art will understand that in alternate
embodiments, essentially any of the electrodes 1200, 1250, 1260 of
FIGS. 12A, 12B, 12C, 12D, and 12E may be mounted upon various types
of release liners in conjunction with identical, similar, and/or
conventional electrodes 150. Use of voided electrodes 1200, 1250
and/or electrodes 1260 that include an internal swatch 1226 may
require release liner embodiments that ensure no overlap between
portions of such electrodes' foil layers and a conductive region or
medium associated with the release liner exists (i.e., release
liner embodiments that ensure a significant amount of transverse
current flow through a length of an electrode's hydrogel layer
1210).
Other electrode designs may facilitate electrical path
characterization while mounted upon a release liner, in conjunction
with determination of whether electrodes are mounted upon the
release liner or a patient's body. FIG. 17 is a cross sectional
view of an electrode 1700 according to another embodiment of the
invention. The electrode 1700 may comprise a conductive adhesive
material, conductive gel layer or hydrogel layer 1710, a foil layer
1720, an insulating layer 1730, and a first lead wire 1740, each of
which may be implemented using conventional materials. The
electrode 1700 further comprises a sonomicrometer 1770 coupled to a
second lead wire 1780.
The sonomicrometer 1770 comprises a piezoelectric transducer
capable of transmitting and/or receiving ultrasonic signals (i.e.,
sound signals having frequencies greater than or equal to 1 MHz).
The sonomicrometer 1770 is positioned upon or partially embedded
within the hydrogel layer 1710. A sonomicrometer 1770 may serve as
an ultrasonic transmitter and/or an ultrasonic receiver. A
sonomicrometer 1770 suitable for incorporation into an electrode
1700 may comprise a piezoelectric transducer available from
Sonometrics Corporation (www.sonometrics.com). As described in
detail hereafter, sonomicrometers 1770 incorporated into a group of
electrodes 1700 may facilitate measurement of a separation distance
between electrodes 1700, thereby determining or indicating whether
electrodes 1700 are mounted upon a release liner or a patient's
body.
FIG. 18 is a perspective view of electrodes 1700 of FIG. 17 mounted
upon the release liner 1400 of FIG. 14A in accordance with an
embodiment of the invention. Relative to FIGS. 14A and 17, like
reference numbers indicate like elements. One electrode 1700 may be
mounted upon one side of the release layer 1410, while another
electrode 1700 may be mounted upon the release layer's opposite
side. The release layer's opening 1422 facilitates hydrogel layer
1710 to hydrogel layer 1710 contact, thereby providing for direct
electrical communication between electrodes 1700.
The first and second lead wires 1740, 1780 of each electrode 1700
may be coupled to a medical device. The medical device may
electrically test or characterize the electrical path through one
electrode's hydrogel layer 1710, through the release layer's
opening 1422, and into the other electrode's hydrogel layer 1710.
In the event that the medical device measures a short or open
circuit condition, one or more electrodes 1700, lead wires 1740,
and/or connectors that couple the electrodes 1700 to the medical
device may be defective.
As the electrodes' hydrogel layers 1710 lose moisture over time, an
impedance level or value associated therewith may increase. If the
medical device measures an impedance value that exceeds a
particular threshold or range, one or both electrodes 1700 may be
non-optimal or unfit for use. The medical device may perform one or
more operations and/or provide one or more indications of electrode
condition in manners described in detail below.
The medical device may issue a separation measurement signal to one
electrode's sonomicrometer 1770 via a second lead wire 1780. In
response, the sonomicrometer 1770 may issue or generate an
ultrasonic pulse, which may travel 1) through the signal generating
electrode's hydrogel layer 1710; 2) through the release layer 1410
and/or the release layer's opening 1422; 3) and into the other
electrode's hydrogel layer 1710, whereupon it may be detected
and/or received by a receiving sonomicrometer 1770. The receiving
sonomicrometer 1770 may issue a reception signal to the medical
device in response to detection of the ultrasonic pulse.
The medical device may calculate or determine a separation distance
between sonomicrometers 1770 based upon the time delay between
issuance of the separation measurement signal and receipt of the
reception signal, in a manner readily understood by those skilled
in the art. Based upon the separation distance, the medical device
may determine whether the electrodes 1700 are mounted upon the
release liner 1400. A separation distance smaller than a given
threshold distance, for example, one inch, provides an indication
that the electrodes 1700 are mounted upon the release liner 1400
rather than a patient's body. In an alternate embodiment, a release
liner 1400 itself may include a sonomicrometer 1770.
In the event that the medical device determines, calculates, or
measures a separation distance significantly greater than that
associated with electrodes 1700 mounted or packaged upon a release
liner 1400, the medical device may determine that the electrodes
1700 are mounted upon a patient's body. Based upon a measured or
determined separation distance, the medical device may further
determine whether the electrodes 1700 are properly positioned upon
the patient's body. For example, the medical device may determine
that the electrodes 1700 are positioned too close together, and
provide a message to a medical device operator indicating such
and/or requesting electrode repositioning. The medical device may
further adjust, modify, or tailor a signal exchange sequence with
the patient based upon a measured or determined electrode
separation distance. For example, a medical device such as an AED
may determine that a measured electrode separation distance
indicates that the electrodes 1700 are mounted upon a large
patient, and increase one or more shock energies accordingly.
In an alternate electrode embodiment, an electrode's foil layer
1720 may include an opening therein (not shown), in a manner
analogous to that described above with reference to FIGS. 12A
through 12C. The sonomicrometer 1770 may be situated or positioned
within such an opening, in which case an ultrasonic signal may
travel directly through one electrode's hydrogel layer 1710 into
another electrode's hydrogel layer 1710 via the opening without
experiencing significant signal attenuation due to the release
layer 1410.
A wide variety of electrode/release liner configurations in
addition those disclosed above may exist. FIG. 19 is a perspective
view of voided electrodes 1250 of FIG. 12C and a conventional
electrode 150 mounted upon a release liner 1900 in accordance with
another embodiment of the invention. The release liner 1900 may
comprise a foldable release layer 1910 and a conductive backing
layer 1960. The foldable release layer 1910 may comprise a
nonconductive, non-stick material having a first mounting or
release portion 1920, a second mounting or release portion 1930,
and a third mounting or release portion 1936. The first, second,
and third mounting portions 1920, 1930, 1936 may respectively
include first a set of openings 1922, a second set of openings
1932, and a third set of openings 1938 therein. The first and
second mounting portions 1920, 1930 may be separated by a first
fold region 1940, while the second and third mounting portions
1930, 1936 may be separated by a second fold region 1942. The
foldable release layer 1910 may be implemented using conventional
materials, such as those described above, and the first, second,
and/or third sets of openings 1922, 1932, 1938 may be cut, stamped,
and/or punched out of such materials in conventional manners.
The conductive backing layer 1960 may comprise a foldable or
bendable sheet or layer of conductive material, such as an Aluminum
or Tin foil layer. Depending upon embodiment and/or implementation
details, the conductive backing layer 1960 may be adhered,
laminated, and/or otherwise attached to the release layer 1910.
Additionally or alternatively, the conductive backing layer 1960
may be held in position via adhesion to hydrogel in regions in
which the first, second and/or third sets of release layer openings
1922, 1932, 1938 expose the backing layer 1960 to electrodes 1250,
150 mounted upon the release layer 1910.
Electrodes 1250, 150 may be mounted upon each of the foldable
release layer's mounting portions 1920, 1930, 1936, for example, in
the manner shown in FIG. 19. Electrodes 1250, 150 mounted in such a
manner reside upon a single side of the foldable release layer
1910; that is, electrodes 1250, 150 so mounted reside upon the same
surface of the foldable release layer 1910. The foldable release
layer 1910 may be folded, bent, or doubled about one or more fold
regions 1940, 1942.
A medical device to which the electrodes 1250 are coupled may test
and/or characterize the electrical path between any pair of
electrodes 1250, 150 and/or all electrodes 1250, 150 in a manner
analogous to that described above. The medical device may provide
one or more indications of electrical path and/or electrode
condition in manners described in detail below.
Those skilled in the art will understand that other
electrode/release liner configurations may include conventional
electrodes 150; voided electrodes 1200, 1250 in accordance with
FIGS. 12A, 12B, and 12C; electrodes 1260 having one or more
swatches 1226 incorporated therein in a manner analogous to that
described above with reference to FIGS. 12D and 12E; sonomicrometer
electrodes 1700; and/or other electrodes. Release liners upon which
such electrodes may be mounted may include can appropriate set of
openings to facilitate electrical communication between electrodes
in manners analogous to those described above.
The release liner and/or electrode embodiments described above
facilitate electrical characterization of packaged electrodes via
electrical contact between electrodes. Release liner and/or
electrode embodiments that facilitate such characterization via
measurements that may not rely upon electrode to electrode contact
are considered in detail hereafter.
FIG. 20 is a perspective view of electrodes 150 mounted upon a
release liner 2000 in accordance with an embodiment of the
invention. The release liner 2000 may comprise a release layer 2010
having two sides and characterized by nonconductive and non-stick
properties. The release layer 2010 may be characterized by a known
thickness and dielectric constant, may be implemented using a
variety of conventional materials including those described
above.
One electrode 150 may be positioned or mounted upon one side of the
release layer 2010, while another electrode may be analogously
positioned upon the release layer's other side. For a given
electrode 150, the effective electrical contact area to the release
layer 2010 may correspond to the area spanned by the electrode's
hydrogel layer. Alternatively, the effective electrical contact
area to the release layer 2010 may be a function of the area of the
electrode's hydrogel layer relative to that of the electrode's foil
layer.
The electrical contact area associated with each electrode 150, as
separated by a release layer having a known thickness and
dielectric constant, forms a type of parallel plate capacitor. A
medical device coupled to electrodes 150 mounted upon a release
liner 2000 in the manner shown in FIG. 20 may therefore measure,
determine, or calculate a corresponding capacitance value. In one
embodiment, the thickness and capacitance associated with the
release liner are approximately 5 mils and 1 nF, respectively. The
effective electrical contact area may be approximately 100 square
centimeters.
If the capacitance value is above or below a predetermined or
expected range, a short or open circuit condition may exist,
possibly indicating a damaged or defective electrical path,
possibly arising from a problem with an electrode 150, wiring,
and/or a connector. In such a situation, the medical device may
provide an indication that the packaged electrodes 150 are unfit
for use, possibly in manners described in detail below.
A medical or measuring device may alternatively or additionally
perform a complex impedance measurement upon electrodes 150 mounted
upon a release liner 2000 as shown in FIG. 20. A complex impedance
may be characterized by a real impedance R (i.e., a resistance);
and an imaginary impedance X (i.e., a reactance in the context of
the present invention). When electrodes 150 are mounted upon a
release liner 2000, a real impedance may correspond to hydrogel
layer moisture content, and an imaginary impedance may correspond
to a capacitance within the electrode/release liner configuration.
As the electrodes' hydrogel layers lose moisture over time, the
medical or measuring device may measure a corresponding increase in
a real impedance R. The medical or measuring device may include
temperature measurement and/or compensation circuitry or elements
to account for manners in which measured impedance levels may vary
as a function of temperature. If the medical or measuring device
determines that a temperature compensated real impedance value
exceeds a given threshold value and/or falls outside an acceptable
range, one or more electrode's hydrogel layers may have dried out
to an extent that such electrodes 150 are no longer optimal or fit
for use. The medical or measuring device may provide an indication
of such, possibly in manners described in detail below.
The magnitude of a real impedance R relative to that of an
imaginary impedance X may determine an extent to which a medical
device can detect or determine a hydrogel layer's condition. In the
embodiment shown in FIG. 20, an imaginary impedance X may dominate
complex impedance measurements. Thus, small changes in a real
impedance R may be difficult to detect, making accurate and/or
detailed characterization of electrode hydrogel layer condition
correspondingly difficult.
Electrode and/or release liner structure may have a significant
impact upon the magnitude of a real impedance R relative to that of
an associated imaginary impedance X. In particular, release liner
and/or electrode structures that minimize an imaginary impedance X
and/or maximize a real impedance R may facilitate determination of
more detailed information about hydrogel layer condition. Release
liner and/or electrode embodiments directed toward maximizing
detectability of changing hydrogel layer conditions are described
in detail hereafter.
FIG. 21A is a plan view of a release liner 2100 according to an
embodiment of the invention. In the embodiment shown, the release
liner 2100 comprises a two-sided release layer 2110 having an
opening 2122 therein; and an insulating swatch or patch 2126 that
covers or fills the opening 2122. The release layer 2110 may
comprise a conventional nonconductive, non-stick material, in a
manner described above. The insulating swatch 2126 may comprise a
thin layer of nonconductive material characterized by a high
dielectric constant. The swatch 2126 may be implemented, for
example, using Polyvinyl Chloride (PVC), which typically exhibits a
dielectric constant ranging between 4.8 and 8; Polyvinlidene
fluoride (PVDF), which may exhibit a dielectric constant ranging
between 8 and 10; a ceramic material such as BaTiO.sub.3, which may
exhibit a dielectric constant ranging between 350 and 6500; and/or
other materials. The thickness of the swatch 2126 in any given
implemented may depend upon manufacturing and/or material handling
considerations. Polymeric swatches 2126 may comprise one or more
film-based layers, and may have a thickness of 1 mil or less.
Ceramic-based swatches 2126 may exhibit a thickness range, for
example, between 2 and 10 mils.
FIG. 21B is a perspective view of electrodes 150 mounted upon the
release liner 2100 of FIG. 21A. One electrode 150 may be positioned
upon one side of the release layer 2110, while the other electrode
150 may be positioned upon the release layer's other side, forming
an electrode 150 to release liner 2100 to electrode 150 assembly
2102. A medical or measurement device to which the electrodes 150
are coupled may perform a complex impedance measurement upon the
assembly 2102.
FIG. 21C is a cross sectional view of the electrode to release
liner to electrode assembly 2102 of FIG. 21B. FIG. 21D is an
equivalent circuit 2190 corresponding to or modeling the assembly
2102 of FIG. 21B. The equivalent circuit 2190 may be characterized
by a first circuit branch 2192 in parallel with a second circuit
branch 2194. The first circuit branch 2192 includes a first
resistance R1 and a first capacitance C1, and may be characterized
by a first impedance Z1. Impedance Z1 may be decomposed or
represented as R1+X1, where X1 is a reactance associated with
capacitance C1, equal to 1/(j.omega.C1). The second circuit branch
2194 includes a second resistance R2 and a second capacitance C2,
and may be characterized by a second impedance Z2. Impedance Z2 may
be represented as R2+X2, where X2 is a reactance associated with
capacitance C2, equal to 1/(j.omega.C2).
The first circuit branch 2192 may correspond to a displacement
current path that excludes an area in which the swatch 2126 covers,
fills, overlaps, and/or blocks the release layer's opening 2122.
That is, the first circuit branch 2192 may correspond to a
displacement current path outside a boundary defined by an area in
which the swatch 2126 covers the opening 2122. This displacement
current path may exist through one electrode's conductive foil and
hydrogel layers, the release layer 2110 (and possibly portions of
the swatch 2126 that extend beyond a boundary defined by the
opening 2122), and the other electrode's conductive foil and
hydrogel layers. Thus, within the first circuit branch 2192,
resistance R1 may correspond to an effective conductive and
hydrogel layer resistance within the electrodes 150 in areas
excluding those in which the swatch 2126 covers the opening 2122.
Similarly, capacitance C1 may correspond to an effective
capacitance of the release layer 2110 in areas excluding those in
which the swatch 2126 covers the opening 2122.
The second circuit branch 2194 may correspond to a displacement
current path through areas or portions of the swatch 2126 that
cover or fill the opening 2122. That is, the second circuit branch
2194 may correspond to the displacement current path from one
electrode's conductive foil and hydrogel layers in an area in which
the swatch 2126 covers the opening 2122; through the swatch 2126
where it covers or fills the opening 2122; and into the other
electrode's conductive and hydrogel layers in this area. Thus,
within the second circuit branch 2194, resistance R2 may correspond
to an effective conductive and hydrogel layer resistance associated
with the electrodes 150 in an area of the swatch 2126 where it
covers the opening 2122, while capacitance C2 may correspond to an
effective capacitance associated with the swatch 2126 in or over an
area defined by the opening 2122.
An effective impedance Z.sub.eff may be defined as
((1/Z1)+(1/Z2).sup.-1, in a manner readily understood by those
skilled in the art. Those skilled in the art will also understand
that an effective current I.sub.eff may thus vary in accordance
with ((1/Z1)+(1/Z2)), or (1/(R1+X1)+1/(R2+X2)). For electrodes 150
in good condition, the values of resistances R1 and R2 may
generally be small. Capacitance C2 may be significantly larger than
capacitance C1, and hence reactance X2 is correspondingly smaller
than reactance X1. Additionally, reactance X2 may be sufficiently
small that it does not overwhelm or dominate the term 1/(R2+X2).
Neither X1 nor X2 generally experience significant changes over
time. Hence, changes in resistance R2 over time, which may
correspond to changes in hydrogel layer moisture content, may
noticeably affect the complex impedance of the assembly 2102. Other
electrode/release liner configurations or embodiments in which
changes in hydrogel layer properties may significantly affect
complex impedance measurements are described in detail
hereafter.
FIG. 22A is a perspective view of a voided electrode 1200 of FIG.
12A and a conventional electrode 150 mounted upon the release liner
2100 of FIG. 21A. Relative to FIGS. 12A and 21A, like reference
numbers indicate like elements. The voided electrode 1200 may be
mounted upon one side of the release layer 2110, while the
conventional electrode 150 may be mounted upon the release layer's
other side, forming a voided electrode 1200 to release liner 2100
to conventional electrode 150 assembly 2102. The voided electrode
1200 may be mounted or positioned such that its void 1222 surrounds
or encompasses at least a portion of the release liner's swatch
2126, namely, that portion of the swatch 2126 that covers, fills,
and/or overlaps the release layer's opening 2122. Those skilled in
the art will understand that the area occupied by the void 1222 may
be larger or smaller than that occupied by the swatch 1226. The
conventional electrode 150 may be positioned such that its hydrogel
layer covers the release layer's opening 2122. Those skilled in the
art will also understand that either of the voided or conventional
electrodes 1200, 150 may be mounted upon the side of the release
liner 2100 upon which the swatch 2126 resides.
FIG. 22B is a cross sectional view of the voided electrode 2100 to
release liner 2100 to conventional electrode 150 assembly 2202, and
FIG. 22C is an equivalent circuit 2290 corresponding to or modeling
the assembly 2202 of FIG. 22A. In the equivalent circuit 2290, a
first circuit branch 2292 may correspond to a displacement current
path outside a boundary defined by the release liner's swatch 2126
where it covers, fills, and/or blocks opening 2122, in a manner
analogous to that described above. Similarly, a second circuit
branch 2294 may correspond to a displacement current path through
an area or region in which the swatch 2126 covers, fills, and/or
blocks the opening 2122, in a manner analogous to that described
above.
The first circuit branch 2292 may include a resistance R1a, a
capacitance C1, and a resistance R1b, and may be characterized by
an impedance Z1. Resistance R1a may correspond to an effective
resistance of the voided electrode's conductive foil areas and
hydrogel layers 1220, 1210 exclusive of areas in which the swatch
2126 covers, fills, and/or blocks the opening 2122. Resistance R1b
may correspond to an effective resistance of the conventional
electrode's conductive foil and hydrogel layers exclusive of areas
in which the swatch 2126 covers the opening 2122. Capacitance C1
may correspond to an effective capacitance of the release layer
2110 in areas excluding those in which the swatch 2126 covers the
opening 2122, and may be accounted for as a reactance X1. Impedance
Z1 may be decomposed or represented as R1a+X1+R1b, in a manner
analogous to that described above.
The second circuit branch 2294 may include a resistance R2a, a
capacitance C2, and a resistance R2b, and may be characterized by
an impedance Z2. Resistance R2a may correspond to an effective
resistance of the voided electrode's hydrogel layer 1210 in areas
associated with the release liner's swatch 2126 where it covers,
fills, and/or blocks the opening 2122 (i.e., an effective
resistance of the voided electrode's hydrogel layer 1210 in an area
in which the void 1222, the hydrogel layer 1210, the swatch 2126,
and the opening 2122 may be coincident). Resistance R2b may
correspond to an effective resistance of the conventional
electrode's conductive foil and hydrogel layers in areas in which
swatch 2126 covers the opening 2122. Capacitance C2 may correspond
to an effective capacitance of the swatch 2126 in an area or region
in which the swatch 2126 covers, fills, overlaps, and/or blocks the
opening 2122, and may be accounted for as a reactance X2. Impedance
Z2 may be decomposed or represented as R2a+X2+R2b, in a manner
analogous to that described above.
In a manner analogous to that describe above, an effective
impedance Z.sub.eff may be defined as ((1/Z1)+(1/Z2)).sup.-1.
Capacitance C2 may be significantly larger than capacitance C1
(i.e., C2>>C1); hence, reactance X2 is correspondingly much
smaller than reactance X1. As a result, the second circuit branch
2294 provides a dominant current path relative to the first circuit
branch 2292. Furthermore, reactance X2 may be sufficiently small
that it does not overwhelm or dominate the term 1/(R2a+X2+R2b).
Neither X1 nor X2 generally experience significant changes over
time.
R2a may correspond to a lateral or transverse current path through
the voided electrode's hydrogel layer 1210. As a result, R2a may be
significantly larger than R2b. Moreover, R2a may exhibit a
magnitude that is approximately equal to or in the same range as
that of X2. As a result, changes in R2a over time, which may
correspond to changes in the condition of the voided electrode's
hydrogel layer 1210 over time, may significantly impact the
effective impedance of the voided electrode 1200 to release layer
2100 to conventional electrode 150 assembly 2202. Via measuring
complex impedance measurement results over time, a medical device
may determine an extent to which a voided electrode 1200 and/or a
conventional electrode 150 mounted upon the release liner 2100 of
FIG. 21A are optimal and/or fit for use. The medical device may
provide an indication of electrode condition in manners described
in detail below.
FIG. 23A is a perspective view of a pair of voided electrodes 1200
of FIG. 12A mounted upon the release liner 2100 of FIG. 21A.
Relative to FIGS. 12A and 21A, like reference numbers indicate like
elements. The voided electrodes 1200 may be mounted upon each side
of the release layer 2110, thereby forming a voided electrode 1200
to release liner 2100 to voided electrode 1200 assembly 2302. One
voided electrode 1200 may be mounted or positioned such that its
void 1222 surrounds or encompasses the release liner's swatch 2126
in an area or region in which the swatch 2126 covers or fills the
release layer's opening 2122. Another voided electrode 1200 may be
positioned on another side of the release layer 2110, such that its
void 1222 surrounds the release layer's opening 2122.
FIG. 23B is a cross sectional view of the voided electrode 1200 to
release liner 2100 to voided electrode 1200 assembly 2302 of FIG.
23A, and FIG. 23C is an equivalent circuit 2390 corresponding to or
modeling the assembly 2302 of FIG. 23A. In the equivalent circuit
2390, a first circuit branch 2392 may correspond to a displacement
current path outside a boundary defined by the release liner's
swatch 2126 where it covers, fills, and/or blocks opening 2122, in
a manner analogous to that described above. Similarly, a second
circuit branch 2394 may correspond to a displacement current path
through an area or region in which the swatch 2126 covers, fills,
and/or blocks the opening 2122, in a manner analogous to that
described above.
The first circuit branch 2392 may include a resistance R1a, a
capacitance C1, and a resistance R1b, and may be characterized by
an impedance Z1. Resistances R1a and R1b may correspond to an
effective resistance of a given voided electrode's conductive foil
and hydrogel layers 1220, 1210 exclusive of areas in which the
swatch 2126 covers, fills, and/or blocks the opening 2122.
Capacitance C1 may correspond to an effective capacitance of the
release layer 2110 in areas excluding those in which the swatch
2126 covers the opening 2122, and may be accounted for as a
reactance X1. Impedance Z1 may be decomposed or represented as
R1a+X1+R1b, in a manner analogous to that described above.
The second circuit branch 2394 may include a resistance R2a, a
capacitance C2, and a resistance R2b, and may be characterized by
an impedance Z2. Resistances R2a and R2b may correspond to an
effective resistance of a given voided electrode's hydrogel layer
1210 in areas associated with the release liner's swatch 2126 where
it covers, fills, and/or blocks the opening 2122, in a manner
analogous to that previously described. Capacitance C2 may
correspond to an effective capacitance of the swatch 2126 in an
area or region in which it covers, fills, overlaps, and/or blocks
the opening 2122, and may be accounted for as a reactance X2.
Impedance Z2 may be decomposed or represented as R2a+X2+R2b, in a
manner analogous to that described above.
In a manner analogous to that describe above, an effective
impedance Z.sub.eff may be defined as ((1/Z1)+(1/Z2)).sup.-1, and
an effective current I.sub.eff may thus vary in accordance with
((1/Z1)+(1/Z2)), or (1/(R1a+X1+R1b)+1/(R2a+X2+R2b)). Capacitance C2
may be significantly larger than capacitance C1, and hence
reactance X2 is correspondingly smaller than reactance X1.
Additionally, reactance X2 may be sufficiently small that it does
not overwhelm or dominate the term 1/(R2a+X2+R2b). Neither X1 nor
X2 generally experience significant changes over time.
In the assembly 2302 of FIGS. 23A and 23B, resistances R2a and R2b
may correspond to lateral current paths through a hydrogel layer
1210. Moreover, R2a and R2b may each exhibit a magnitude that is
approximately equal to or in the same range as that of X2. As a
result, changes in R2a and R2b over time, which may correspond to
changes in the condition of the voided electrodes' hydrogel layers
1210 over time, may significantly impact the effective impedance of
the voided electrode 1200 to release layer 2100 to voided electrode
1200 assembly 2302. Via measuring and/or recording complex
impedance over time, a medical or measurement device may determine
an extent to which a voided electrode 1200 and/or a conventional
electrode 150 mounted upon the release liner 2100 of FIG. 21A are
optimal and/or fit for use. The medical device may provide an
indication of electrode condition in manners described in detail
below.
FIG. 24A is a layered plan view of a release liner 2400 according
to another embodiment of the invention. The release liner 2400
comprises a nonconductive, non-stick release layer 2410 and a
conductive backing layer 2460. The release layer 2410 includes a
first opening 2422, a second opening 2432, and a nonconductive
swatch 2426 that covers, fills, overlaps, and/or blocks one of the
openings 2422, 2432. The release layer 2410 and/or the conductive
backing layer 2460 may be implemented using materials previously
described. The first and second openings 2422, 2432 may be cut,
stamped, or punched out of the release layer 2410 in a conventional
manner. In an alternate embodiment, one or both of the first and
second openings 2422, 2432 may comprise sets of openings. Finally,
the swatch 2426 may comprise a thin material characterized by a
high or generally high dielectric constant, such as a polymeric
and/or ceramic material described above.
The conductive backing layer 2460 may be adhered, laminated, and/or
otherwise attached to the release layer 2410, thereby maintaining
or holding the backing layer 2460 in a given position. Additionally
or alternatively, the conductive backing layer 2460 may be held in
position by adhesion between the conductive backing layer 2460 and
electrodes' hydrogel layers in regions defined by the release
layer's openings 2422, 2432.
FIG. 24B is a plan view of a conventional electrode 150 and a
voided electrode 1200 of FIG. 12 mounted upon the release liner
2400 of FIG. 24A. Relative to FIGS. 12 and 24A, like reference
numbers indicate like elements. The voided electrode 1200 may be
mounted upon the release layer 2410 such that its void 1222
surrounds the release layer's first opening 2422, thereby
surrounding at least a portion of the swatch 2426. The conventional
electrode 150 may be mounted upon the release layer 2410 such that
its hydrogel layer covers the second opening 2422.
A medical or measurement device to which the voided and
conventional electrodes 1200, 150 are coupled may perform a complex
impedance measurement in a manner analogous to that describe above
with respect to FIGS. 22A and 22B. Based upon the result of the
impedance measurement, the medical or measurement device may
provide an indication of electrical path condition and/or electrode
condition or fitness for use, in manners described in detail
below.
FIG. 25A is a plan view of a release liner 2500 according to
another embodiment of the invention. The release liner 2500
comprises a foldable release layer 2510 and a conductive backing
layer 2560. The foldable release layer 2510 may comprise a
nonconductive, non-stick material such as those previously
described. The foldable release layer 2510 includes a first
mounting portion 2520 having a first opening 2522; a second
mounting portion 2530 having a second opening 2532; a nonconductive
swatch 2526 that covers, fills, overlaps, and/or blocks the first
openings 2522; and a fold or midline region 2540. The first and
second openings 2522, 2532 may be cut, stamped, or punched out of
the release layer 2510 in a conventional manner. In an alternate
embodiment, one or both of the first and second openings 2522, 2532
may comprise sets of openings. The conductive backing layer 2560
may be implemented using conventional materials in a manner
analogous to that described above. Finally, the swatch 2526 may
comprise a thin material characterized by a high or generally high
dielectric constant, such as a polymeric and/or ceramic material
described above.
The foldable release layer 2510 may be folded, bent, or doubled in
either direction about its fold or midline region 2540 to surround
or encase portions of the conductive backing layer 2560. The
backing layer 2560 may be adhered, laminated, and/or otherwise
attached to the foldable release layer 2510, thereby maintaining
the conductive backing layer 2560 in a given position. Additionally
or alternatively, in regions defined by the foldable release
layer's openings 2522, 2532, adhesion between the conductive
backing layer 2560 and electrodes' hydrogel layers may hold the
backing layer 2560 in position.
FIG. 25B is a perspective view of a pair of voided electrodes 1200
of FIG. 12A mounted upon the release liner 2500 of FIG. 25A.
Relative to FIGS. 12A and 25A, like reference numbers indicate like
elements. One voided electrode 1200 may be mounted such that its
void 1222 surrounds the first opening 2522 within the first
mounting portion 2520, thereby surrounding at least a portion of
the swatch 2526. Another voided electrode may be mounted such that
its void 1222 surrounds the second opening 2532 within the second
mounting portion 2530. Voided electrodes 1200 mounted in the manner
shown in FIG. 25B reside upon an identical side of the release
layer 2510, while the conductive backing layer 2560 may maintain
contact with portions of another side of the release layer
2510.
A medical or measurement device coupled to voided electrodes 1200
mounted as shown in FIG. 25B may perform a complex impedance
measurement in a manner analogous to that describe above with
respect to FIGS. 23A and 23B. Based upon the result of the
impedance measurement, the medical or measurement device may
provide an indication of electrical path condition and/or electrode
condition or fitness for use, in manners described in detail
below.
FIG. 26 is a perspective view of a release liner 2600 according to
another embodiment of the invention, and a pair of voided
electrodes 1200 of FIG. 12A mounted thereupon. Relative to FIG.
12A, like reference numbers indicate like elements. In the
embodiment shown, the release liner 2600 comprises a first release
layer or sheet 2620, a second release layer or sheet 2630, and a
conductive layer or medium 2660 disposed or residing therebetween.
The first release layer 2610 includes a first opening 2622 and a
swatch 2626 that covers, fills, overlaps, and/or blocks the first
opening 2622. The second release layer 2630 includes a second
opening 2632 therein. The first and second release layers 2620 may
comprise nonconductive, non-stick materials such as those
previously described, and first and second openings 2622, 2632 may
be formed in conventional manners as previously described. The
swatch 2626 may comprise a thin material characterized by a high
dielectric constant, and may be formed or fabricated using
polymeric and/or ceramic materials such as those described
above.
The conductive layer 2660 may comprise a sheet or layer of
conductive material, such as an Aluminum or Tin foil layer, or a
hydrogel layer. The conductive layer 2660 may be adhered,
laminated, and/or otherwise attached one or both release layers
2620, 2630. Additionally or alternatively, the conductive layer
2660 may be held in position by hydrogel adhesion in regions in
which the first and second release layers' openings 2622, 2632
expose the conductive backing layer 2660 to the electrodes
1200.
One voided electrode 1200 may be mounted or positioned such that
its void 1222 surrounds the first release layer's opening 2622,
thereby surrounding at least a portion of the swatch 2622. Another
voided electrode 1200 may be mounted such that its void 1222
surrounds the second release layer's opening 2632. A medical device
coupled to the voided electrodes 1200 mounted as shown in FIG. 26
may perform a complex impedance measurement in a manner analogous
to that describe above with respect to FIGS. 23A and 23B. Based
upon the result of the impedance measurement, the medical device
may provide an indication of electrical path condition and/or
electrode condition or fitness for use, in manners described in
detail below.
In essentially any of the embodiments shown in FIGS. 21A, 21B, 21C,
22A, 22B, 23A, 23B, 24A, 24B, 25A, 25B, and/or 26, a swatch 2126,
2226, 2326, 2426, 2526, 2626 may be adhered, bonded, laminated,
and/or otherwise attached to a release liner 2100, 2400, 2500,
2600. Alternatively, direct attachment of a swatch 2126, 2226,
2326, 2426, 2526, 2626 to a release liner 2100, 2400, 2500, 2600
may be omitted. In such a situation, a swatch 2126, 2226, 2326,
2426, 2526, 2626 may be placed or positioned upon a release liner
2100, 2400, 2500, 2600 prior to placement or positioning of
electrodes thereupon; or, a swatch 2126, 2226, 2326, 2426, 2526,
2626 may simply be appropriately positioned upon an electrode's
hydrogel layer 1210 prior to placement or positioning of the
electrode upon the release liner. Adhesion to an electrode's
hydrogel layer 1210 may be sufficient to hold or maintain a swatch
2126, 2226, 2326, 2426, 2526, 2626 in a desired position. Upon
removal from the release liner 2100, 2400, 2500, 2600, the
performance or behavior of the electrode 150, 1200 may be
essentially unaffected provided that the swatch 2126, 2226, 2326,
2426, 2526, 2626 is sufficiently small.
Variations upon the electrode/release liner embodiments above, such
as those shown in FIGS. 24B, 25B, and 26, may exist. Such
variations may involve other electrode embodiments, additional
numbers of electrodes, and/or other release liner embodiments, in a
manner consistent with the scope of the invention.
As indicated above, a medical or measurement device coupled to
electrodes mounted upon a release liner may test and/or
characterize an electrical path associated with the mounted or
packaged electrodes in a variety of manners. Furthermore, the
medical or measurement device may provide various indications of
electrode condition and/or fitness for use, as described in detail
hereafter. In the context of the present invention, a medical
device may comprise essentially any device capable of exchanging
electrical signals and/or electrical energy with a patient's body
via a set of electrodes, and may be, for example, an AED.
Similarly, a measurement device may comprise essentially any type
of device capable of performing electrical measurements upon a set
of electrodes mounted upon a release liner in accordance with the
present invention.
FIG. 27 is a block diagram of an AED 2700 coupled to electrodes
2794 mounted upon a release liner 2798 in accordance with an
embodiment of the invention. The AED 2700 may comprise a power
source or battery 2712; a power management unit 2714; an electrode
signal management unit 2716; an electrode interface 2718; a first
and a second gate array 2720, 2722; a memory 2730; a processing
unit 2732; a communication interface or port 2734 that may be
coupled to a data card 2736; an operator interface 2740 that
includes a power or on/off switch 2742, a status indicator 2744, a
display 2746, a contrast control 2748, a speaker 2750, a microphone
2752, a set of Light Emitting Diodes (LEDs) 2754, a shock button
2756, and an input interface 2758; a status measurement unit 2760;
and a temperature sensor 2770.
The electrode interface 2718 may be coupled via a connector 2710 to
a plurality of electrodes 2794 mounted upon a release liner 2798.
The release liner 2798 may be any type of structure that provides a
non-stick surface upon which electrodes may be mounted, and which
facilitates electrical characterization of electrical current path
condition and/or electrode condition or fitness for use. The
release liner 2798 may comprise any type of release liner
embodiment described or disclosed herein. The electrodes 2794 may
be of any type disclosed herein, and/or another type. Each
electrode 2794 may include a corresponding lead wire 2796 that
facilitates coupling to the connector 2710. The electrodes 2794 are
operable to sense a patient's ECG (not shown) and deliver an
electrical waveform, pulse, or shock when mounted upon a patient's
body (not shown). The electrode signal management unit 2716 may
manage signal and/or energy exchange between the electrodes 2794
and other AED elements via the electrode interface 2718. The
electrode signal management unit 2716 may include impedance
compensation circuitry, such as that referenced above.
The status measurement unit 2760 may perform and/or direct periodic
monitoring of various AED elements, systems, and/or subsystems,
either automatically or in response to an AED operator's request.
Operator requests may be received via the input interface 2758,
which may include one or more buttons and/or a keypad. The status
measurement unit 2760 may also direct the status indicator 2744
and/or the display 2746 to generate and/or present information or
data to an AED operator corresponding to an operational condition
of such AED elements, systems, and/or subsystems.
The status measurement unit 2760 and/or the electrode signal
management unit 2716 may include electrical measurement circuitry
or elements that facilitate electrical path and/or electrode
characterization in accordance with the present invention. The
status measurement unit 2760, possibly in conjunction with the
memory 2730, the data card 2736, the processing unit 2732, the
first gate array 2720, the second gate array 2722, and/or the
temperature sensor 2770 may periodically or continually initiate,
manage, direct, and/or perform electrical path characterization
operations to determine the status and/or operating condition of
one or more portions of an electrical path defined by the connector
2710, the lead wires 2796, the electrodes 2794, and the release
liner 2798. Based upon one or more temperature measurements
received via the temperature sensor 2770, the status measurement
unit 2760 may adjust electrical measurement or test parameters to
facilitate temperature compensated electrical characterization
operations. The temperature sensor 2770 may comprise, for example,
a thermocouple. One or more portions of the temperature sensor may
be external to the AED 2700.
In one embodiment, one or more formulas or equations and/or data
tables derived from and/or based upon empirical impedance versus
temperature data may reside within the memory 2730. Via insertion
of a current or most-recent temperature measurement and a
corresponding current or most-recent impedance measurement into an
appropriate equation, the status measurement unit 2760 and/or the
processing unit 2732 may determine an actual, corrected, or
adjusted impedance value corresponding to mounted electrodes
currently under consideration. An equation that provides corrected
or adjusted impedance values in accordance with temperature and
measured impedance values may be determined, for example, by
standard curve-fitting techniques following empirical data
acquisition. The status measurement unit 2760 and/or the processing
unit 2732 may alternatively or additionally rely upon one or more
data tables to look up a corrected or adjusted impedance value
corresponding to mounted electrodes currently under consideration.
Those skilled in the art will recognize that a data table lookup
procedure may return a closest or an interpolated value depending
upon implementation details.
The status measurement unit 2760 may also periodically or
continually initiate, perform, manage, and/or direct determination
or calculation of one or more estimated or expected time intervals
during which electrodes 2794 are likely to exhibit a given
operating condition. Such determinations or calculations may be
performed in conjunction with the memory 2730, the data card 2736,
the processing unit 2732 and/or one or both gate arrays 2720, 2722.
The memory 2730 and/or the data card 2736 may store program
instruction sequences for initiating, performing, and/or directing
electrical path characterization operations. Finally, the status
measurement unit 2760 may initiate or perform the aforementioned
operations automatically or in response to an AED operator's
request.
Electrical path characterization operations may include or involve
temperature compensated impedance measurements such as those
described herein, as well as generation, presentation, and/or
provision of one or more indications of electrical path and/or
electrode condition. Electrical path characterization operations
may involve stored data, such as electrical measurement results
obtained or determined at one or more earlier times. Such stored
data may be used, for example, to determine a present rate of
change in electrode fitness, or an estimate thereof. Stored data
may reside within the memory 2730, and/or upon the data card
2736.
Based upon measurement results obtained and/or calculations or
determinations made during the electrical path characterization
operations, the status measurement unit 2760 may direct the status
indicator 2744, the display 2746, the speaker 2750, and/or the LEDs
2754 to generate and/or present status information and/or a set of
messages to an AED operator. The status information and/or messages
may be in audible, textual, symbolic, and/or graphical formats.
The status information and/or the messages may indicate that the
electrical path is in adequate, acceptable, or good condition, or
that one or more portions of the electrical path may be damaged or
defective. Alternatively or additionally, the status information
and/or the message may provide an indication of electrode condition
or fitness for use. An AED operator may subsequently take
appropriate action if required, such as replacement of packaged
electrodes.
In the event that an electrical path characterization operation
and/or impedance measurement corresponds to a short or open circuit
condition, a connector 2710, a lead wire 2796, an electrode 2794,
and/or one or more portions of the release liner 2798 may be
damaged and/or defective. In such a case, the status measurement
unit 2760 may direct the status indicator 2744, the display 2746,
and/or the speaker 2750 to present a corresponding message or
indication to an AED operator. Such a message may be, for example,
"REPLACE ELECTRODES IMMEDIATELY."
In the event that an electrical path characterization operation
and/or impedance measurement results in a measured impedance value
exceeding a given value or falling outside a given range, the
status measurement unit 2760 may direct the status indicator 2744,
the display 2746, and/or the speaker 2750 to generate and/or
present a corresponding message, for example, "REPLACE ELECTRODES
SOON." The status measurement unit 2760 or other element may
additionally or alternatively generate a beep or other sound until
electrode replacement has occurred.
The status indicator 2744 may alternatively or additionally
incorporate, generate, present and/or maintain one or more
graphical or other type of visual metaphors that provide an
indication of electrode condition and/or an expected amount of
electrode lifetime remaining. Various types of indicators and/or
interfaces for indicating electrode condition and/or an expected
amount of electrode lifetime remaining are described in detail
hereafter.
FIG. 28A is an illustration of an electrode condition indicator
2800 in accordance with an embodiment of the invention. The
electrode condition indicator 2800 may comprise a panel 2810 and an
indicating element 2830. The panel 2810 may include a set of
quality markings and/or regions 2812, 2814, 2816, where each such
region 2812, 2814, 2816 corresponds to an electrode operating
condition or operating condition range. For example, the electrode
condition indicator 2800 may include a first quality region 2812
corresponding to good or optimal electrode condition; a second
quality region 2814 corresponding to acceptable or fair electrode
condition; and a third quality region 2816 corresponding to poor or
unacceptable electrode condition. Other embodiments may incorporate
additional or fewer quality regions. For example, in an alternate
embodiment, an electrode condition indicator 2800 may include
quality regions corresponding to an excellent quality or condition
rating, a good quality or condition rating, an acceptable quality
or condition rating, a poor quality or condition rating, and an
unusable quality or condition rating. Any given quality region
2812, 2814, 2816 may include one or more color codings; and/or one
or more quality regions 2812, 2814, 2816 may include text and/or
symbols corresponding to an electrode operating condition.
The indicating element 2830 may comprise an arrow, needle, bar, or
other type of element that may be positioned within any given
quality region 2812, 2814, 2816. Based upon electrical path
characterization and/or impedance measurement results, the status
measurement unit 2760 of FIG. 27 may issue signals to the electrode
condition indicator 2800 to set or establish a given position for
the indicating element 2830 relative to the quality regions 2812,
2814, 2816, The indicating element's relative position may provide
a fuel gauge metaphor for electrode condition and/or fitness for
use. As electrode condition deteriorates over time, the indicating
element 2830 may move into and/or through quality regions that
correspond to poorer electrode fitness for use.
The indicating element 2830 may additionally or alternatively
comprise or include a device or interface that changes color in
response to changes in a surrounding environment, such as
variations in relative humidity. The indicating element 2830 may
incorporate one or more color references to convey a degree of
reliability and/or an estimated usable electrode lifetime.
The electrode condition indicator 2800 may be implemented in a
graphical manner upon an electrical interface such as a status
indicator 2744 or display 2746 of FIG. 27. Alternatively, the
electrode condition indicator 2800 may be implemented as a physical
interface that may comprise conventional electrical, mechanical,
electromechanical, chemical, and/or electrochemical elements. Such
a physical interface may form a portion, subsystem, or element of
the status indicator 2744. For example, the panel 2810 may be
implemented as a physical element within a corresponding housing
(not shown), and the indicating element 2830 may be a piece of
plastic and/or metal coupled to a shaft (not shown). The shaft may
be coupled to a positioning device or actuator (not shown) that is
responsive to signals received from the status measurement unit
2760 of FIG. 27.
FIG. 28B is an illustration of an electrode condition indicator
2850 according to another embodiment of the invention. Relative to
FIG. 28A, the electrode condition indicator 2850 of FIG. 28B may
comprise corresponding, identical and/or essentially identical
types of elements; hence, like reference numbers indicate like or
corresponding elements. In the embodiment of FIG. 28B, the
indicating element 2830 may comprise a bar that obscures, blocks,
or covers one or more quality regions 2812, 2814, 2816 and/or
portions thereof, successively exposing or blocking regions 2812,
2814, 2816 corresponding to poorer electrode condition or fitness
for use over time in response to signals received via the status
measurement unit 2760 of FIG. 27. The indicating element 2830 in
such an embodiment may exhibit generally continuous or successive
movement through one or more quality regions 2812, 2814, 2816 over
time.
FIG. 29A is an illustration of a remaining time indicator 2900 in
accordance with an embodiment of the invention. The remaining time
indicator 2900 may comprise a panel 2910 and an indicating element
2930, in a manner analogous to that described above for the
electrode condition indicator 2800 of FIG. 28A. The panel 2910 may
include a set of regions and/or markings 2912, 2914, 2916. Such
markings may correspond to an estimated amount of time that an
electrode may be likely to remain at a given performance or
condition level, or an estimated amount of time remaining before
electrode replacement is likely to be required.
For example, a first marking 2912 may correspond to a duration of
twelve months, while a second and a third marking 2914, 2916 may
correspond to a duration of twenty four and thirty six months,
respectively. Those skilled in the art will recognize that the
first, second, and/or third markings 2912, 2914, 2916 may
correspond to time periods other than those recited herein. Each
region or marking 2912, 2914, 2916 may include associated text that
indicates a time interval and/or a condition to which the region or
marking 2912, 2914, 2916 corresponds. Each region or marking may
also be color coded, in a manner analogous to that described above
with reference to FIG. 28A.
The indicating element 2930 may comprise an arrow, needle, bar, or
other type of element that may be positioned upon, within, or
between any given region or marking 2912, 2914, 2916. Based upon 1)
current and/or most-recent electrical path characterization and/or
impedance measurement results; 2) prior electrical path
characterization and/or impedance measurement results; and/or 3)
empirical data characterizing hydrogel moisture loss, impedance
measurement rates of change, and/or other factors that may affect
electrode condition over time, the status measurement unit 2760 may
issue signals to the remaining time indicator 2900 to set or
establish a given position for the indicating element 2930 relative
to the regions or markings 2912, 2914, 2916.
The position of the indicating element 2930 relative to the
markings 2912, 2914, 2916 may convey, for example, that the
electrodes have approximately X months left in an optimal
performance zone, or Y months remaining until replacement is
recommended or required, where determination of X and/or Y may be
based upon a rate of change in current, prior, and/or empirical
electrical properties. Electrical path property, characterization,
and/or impedance measurement results, as well as the aforementioned
empirical properties or data, may be stored within the memory of
the AED 2700 of FIG. 27. The memory may include various types of
nonvolatile and/or Read Only Memory (ROM) to facilitate efficient
storage of such information.
In a manner analogous to that for the electrode condition indicator
of FIG. 28A, the position of the indicating element 2930 within the
remaining time indicator 2900 relative to the regions or markings
2912, 2914, 2916 may provide a fuel gauge metaphor for an expected
remaining electrode lifetime. As electrode condition deteriorates
over time, the indicating element 2930 may move through or past
regions and/or markings 2912, 2914, 2916 that correspond to shorter
or decreased expected electrode lifetime.
The remaining time indicator 2900 may be implemented in a graphical
manner upon an electrical interface such as a status indicator 2744
or display 2746 of FIG. 27. Alternatively, the remaining time
indicator 2900 may be implemented as a physical interface that may
comprise conventional electrical, mechanical, and/or
electromechanical elements. Such a physical interface may form a
portion, subsystem, or element of the status indicator 2744. For
example, the panel 2910 may be implemented as a physical element
within a corresponding housing (not shown), and the indicating
element 2930 may be a piece of plastic and/or metal coupled to a
shaft (not shown). The shaft may be coupled to a positioning device
or actuator (not shown) that is responsive to signals received from
the status measurement unit 2760 of FIG. 27.
FIG. 29B is an illustration of a remaining time indicator 2950 in
accordance with another embodiment of the invention. Relative to
FIG. 29A, the remaining time indicator 2950 of FIG. 29B may
comprise corresponding, identical and/or essentially identical
types of elements; hence, like reference numbers indicate like
elements. In the embodiment of FIG. 29B, the indicating element
2930 may comprise a bar that obscures, blocks, or covers one or
more regions or markings 2912, 2914, 2916 and/or portions thereof,
successively exposing or blocking such markings 2912, 2914, 2916 to
indicate diminishing expected electrode lifetime in response to
signals received over time via the status measurement unit 2760 of
FIG. 27.
Any given electrode condition indicator 2800, 2850 and/or remaining
time indicator 2900, 2950 may additionally or alternatively be
incorporated into a packaged electrode structure. FIG. 30 is a
perspective view of a package 3000 in which an indicator 3080 and
electrodes 3094 mounted upon a release liner 3098 reside. The
electrodes 3094 and/or the release liner 3098 may be of a variety
of types, including those described herein. Relative to FIGS. 28A
and 29A, like reference indicate like elements.
The package 3000 may comprise a housing 3050 having a removable lid
3052 and an electrical interface 3060, in a manner analogous to
that described above in relation to FIG. 4. Electrodes 3094 mounted
upon the release liner 3098 may be sealed within the package 3000.
The electrical interface 3060 may comprise a connector that
facilitates electrical coupling of the electrodes 3094, and
possibly the indicator 3080, to a medical device. The indicator
3080 may comprise an electrode condition indicator 2800, 2850
and/or a time remaining indicator 2900, 2950 such as those
previously described. The indicator 3080 may reside within or upon
the package 3000.
In one embodiment, the indicator 3080 may be coupled to a medical
or measurement device, and thus the medical or measurement device
may provide electrical power as well as measurement and/or
computational capabilities required to indicate electrode fitness
for use and/or an estimated duration associated with an electrode
condition via the indicator 3080. In an alternate embodiment, the
indicator 3080 may comprise an electrode condition and/or time
remaining indicator 2800, 2850, 2900, 2950, plus a control circuit
3082 and an independent power source 3084 such as a battery. The
control circuit 3082 may include measurement, calculation, and/or
processing elements necessary for determining an electrode
condition and/or an estimated duration corresponding to electrode
condition.
A medical or measurement device may itself include an electrode
condition and/or a time remaining indicator 3080 therein or
thereupon. FIG. 31 is a block diagram of an AED 3100 that includes
an indicator 3080. Relative to FIGS. 27 and 30, like reference
numbers indicate like elements. The indicator 3080 may comprise an
electrode condition and/or a time remaining indicator, which may be
identical, essentially identical, and/or analogous to those
described above with respect to FIGS, 28A, 28B, 29A, and/or
29B.
* * * * *