Wearable defibrillator patch

Abstract

A long term WCD patch for continuous wearing by a patient including: an adhesive ring configured to be adhered to skin of the subject; and a conductive portion including a conductive hydrogel interface, wherein the adhesive ring has an inner diameter smaller than an outer diameter of the conductive hydrogel interface.

Description

[0001] WEARABLE DEFIBRILLATOR PATCH

[0002] CROSS REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority from US provisional patent application No. 63 / 745,335 filed January 15, 2025, which is expressly incorporated herein by reference in its entirety.

[0004] FIELD

[0005] Embodiments disclosed herein relate to long term medical patches for use with wearable defibrillation devices.

[0006] BACKGROUND

[0007] Medical patches may be used for various applications and in conjunction with appropriate devices. Examples of medical patches include electrocardiogram (ECG) patches, glucose monitoring patches, and patches used with cardiac monitoring devices and automated cardiac defibrillators. Such patches may in many cases include an inner active area and an outer adhesive zone. Most patches may be used for a limited time period, and have a limited surface area.

[0008] Reference is made herein to two examples of such patches: patches used in automated electrical defibrillators (AED) where such patches are used for both detecting the ECG of a patient as well as for delivering high energy (high voltage and high current) shock to such a patient when the patient suffers from sudden cardiac arrest or ventricular fibrillation (VF); and for wearable cardioverter defibrillators (WCD) using disposable patches and used to provide protection for patients at high risk of sudden cardiac arrest. Unlike the use in an AED, when the usage of the patches is temporary, in the case of a WCD, patches are used for a longer period when patients are active (generally go about daily activities).

[0009] As above, in AED usage, short-term disposable patches may be connected to a patient's chest for both detecting / sensing the ECG signal of the patient as well as for delivering a high energy shock if a life-threatening arrhythmia was detected by the AED. The usage of the shortterm patches is temporary and since the patient may be unconscious and / or supine, the adhesive area of the patches is used only to keep the patches in place for the relatively short period ofdetection and shock, in most cases for few minutes or at most for several hours (such as when used with ICU patients).

[0010] Patches for WCDs, herein referred to as “long-term patches”, or “wearable patches” may be required to remain on the patient’s skin for much longer periods (usually for days or even weeks), and require a degree of flexibility as the patient is not supine but rather is moving and performing daily activities. Further, the long-term patches may also be exposed to liquids such as skin fluids, and liquids from showering or bathing. During the period when adhered to the patient, wearable patches should not lose their functionality, level of performance and the capabilities for sensing ECG and / or delivering a shock when required.

[0011] A typical structure of a wearable patch 100 known in the art that may be used for ECG detection / delivery of defibrillation shock is shown in FIG. 1. A conductive surface 102 in the middle of the patch may be fully or partially surrounded by a skin adhesive layer 104. Conductive surface 102 may include a conductive hydrogel material positioned between the skin of the patient and the active conductor section of the patch. A conducting wire 106 may connect the conductive surface to the WCD electrical system. Skin adhesive layer 104 may include laminated layers or any other skin adhesive material that bonds with the skin in order to hold the wearable patch in place and prevent the conductive surface 102 from peeling. Defibrillator patches are generally required by standards to be not less than a minimum size of a defibrillation area, which currently is 50cm2.

[0012] The conductive surface must be in full contact with the skin of the patient (via the conductive hydrogel layer) to verify the efficiency and efficacy of the delivered shock. However, the conductive hydrogel may absorb bodily fluids (such as sweat) while the patch is adhered to a patient which may cause the hydrogel to expand in volume and / or to migrate on the skin due to body movement, which may then cause the hydrogel materials together with skin fluids to weaken the contact of the skin layer adhesive around the edges of the inner side of the patch, a process that, over time, will peel the adhesive away from the skin such that the patch is no longer efficient.

[0013] In a typical wearable patch, the adhesive layer is required to be flexible and stretchable. By contrast, the conductive layer may be semi-rigid (somewhat flexible but not stretchable) and skin movement may eventually cause the difference in flexibility of the adhesive and conductive parts to result in peeling away of the adhesive layer from the skin of the patient resulting in detachment of the conductive area from the skin. Alternatively or additionally, the difference in movement of the adhesive and conductive layers relative to the skin may cause discomfort to thepatient such that the patient peels away, moves, or removes the wearable patch. In either case the patch may be rendered less shock-efficient, or (if removed) completely ineffective.

[0014] There is therefore a need for, and it would be advantageous to have a WCD patch which may adhere to the body for a period of up to 30 days while enabling the patient to comfortably continue with a regular daily routine including moving, bathing, sitting, lying down, and so forth, while preventing the hydrogel layer from peeling away or migrating or otherwise damaging the adhesive layer.

[0015] SUMMARY

[0016] Exemplary embodiments disclosed herein relate to long term WCD patches that include a flexible portion covering an air gap that provides separation between, and enables relatively independent movement of, an adhesive layer adhered to the skin of the patient and a conductive layer that remains in conductive contact with the skin of the patient. The combined flexible portion and air gap thus may compensate for body movements (functioning as a “moment absorber”) while keeping the patch effectively conductive. Further, in some embodiments, an inner diameter of an adhesive ring of the patch may extend underneath a hydrogel conductive interface in order to protect the inner diameter of the adhesive ring from being in contact with the edges of the hydrogel conductive interface that may shift and / or expand due to absorption of skin fluids by the hydrogel during patch usage, to thus prevent peeling off of the adhesive ring from the skin caused by such hydrogel shifting / expansion. Further, the patches described herein are connected via cables to the WCD such that the WCD itself does not need to be part of the patches (such as by being mounted onto one of the patches) and the WCD does not need to be adhered to the patient’s skin (directly or mounted onto one of the patches).

[0017] Consistent with disclosed embodiments, a WCD patch for wearing by a subject may include: a flexible outer ring that is configured to be adhered to skin of the subject and a rigid or semi-rigid conductive portion that may be partially separated from the outer ring by an air gap, wherein the flexible outer ring includes an adhesive ring, wherein the conductive portion includes a conductive hydrogel interface, and wherein the adhesive ring has an inner diameter smaller than an outer diameter of the conductive hydrogel interface.In some embodiments, the patch further includes a flexible portion that extends over the air gap, at least partially over the outer ring of the conductive portion, and into or over the conductive portion.

[0018] In some embodiments, the flexible outer ring further includes a barrier ring, the conductive portion further includes a conductive layer, and an inner diameter of the barrier ring is larger than an outer diameter of the conductive interface and conductive layer thereby forming the air gap.

[0019] In some embodiments, a shape cover layer extends at least partially over the outer ring, over the air gap, and over the conductive portion and is adhered to the barrier ring and to the conductive layer. In some embodiments, a patch cover layer extends over the shape cover layer such that the shape cover layer and patch cover layer both extend over the air gap to form the flexible portion.

[0020] In some embodiments, the patch and shape cover layers have substantially the same diameter. In some embodiments, a semi-rigid isolated stiffener layer is positioned between the patch cover layer and shape cover layer over the conductive layer and has substantially the same diameter as the conductive layer or smaller.

[0021] In some embodiments, the conductive layer is printed onto a substrate layer positioned between the conductive layer and the shape cover layer, and wherein the substrate layer has substantially the same diameter as the conductive layer. In some embodiments, the conductive layer is printed onto the shape cover layer.

[0022] In some embodiments, the WCD patch further includes an electrical wire positioned between the shape and patch cover layers and connected to an electrical crimp washer that extends through the shape cover layer and conductive layer before terminating in a conductive eyelet that is in electrical contact with the conductive layer, wherein the electrical wire extends out of the wearable patch and is configured to be connected to an WCD to thereby provide electrical energy flow between the WCD and the conductive layer.

[0023] In some embodiments, the adhesive ring has adhesive configured to adhere to human skin. In some embodiments, the air gap has a width of between 0.1mm-20mm.

[0024] In some embodiments, the wearable patch has a defibrillation area of at least 50cm2or the minimum area according to applicable standards.

[0025] In some embodiments, the flexible portion and air gap enable the rigid or semi-rigid conductive portion to remain in conductive contact with the skin while the flexible outer ring aswell as the flexible portion flex and stretch as needed due to body movements and related skin movements of the subject.

[0026] As used herein, the term “patch” may describe an WCD patch incorporating one or both of a sensing electrode and a defibrillation electrode. The terms “patient” and “subject” may be used herein interchangeably.

[0027] As used herein, in some embodiments, flexible materials may have a Young’s modulus of between 0.01-1.5 GPa, semi-rigid materials may have a Young’s modulus of between 1.5-3 and rigid materials may have a Young’s modulus greater than 3. “Long-term” as used herein refers to a period of 1-30 days.

[0028] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Aspects, embodiments and features disclosed herein will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. Like elements may be marked with like numerals in different figures, where:

[0031] FIG. 1 is a drawing of a known medical patch;

[0032] FIG. 2A is a drawing showing a plan view of a wearable patch according to some implementations ;

[0033] FIG. 2B is a drawing showing a perspective exploded view of a wearable patch according to some implementations;

[0034] FIG. 2C is a drawing showing a cross-sectional view of a wearable patch according to some implementations ;

[0035] FIG. 2D is a drawing showing a plan view of a wearable patch according to some implementations ;

[0036] FIG. 3A is a drawing showing a cross-sectional view of a wearable patch in a noncontracted state according to some implementations;

[0037] FIG. 3B is a drawing showing a cross-sectional view of a wearable patch in a contracted state according to some implementations.DETAILED DESCRIPTION

[0038] Exemplary embodiments disclosed herein relate to a wearable patch for use with an WCD. FIGS.2A-2D and 3A-3B are illustrations of a WCD patch 200 according to some implementations. FIG. 2A is a drawing showing a plan view of wearable patch 200. FIG. 2B is a drawing showing a perspective exploded view of wearable patch 200. FIG. 2C is a drawing showing a cross-sectional view of wearable patch 200. FIG. 2D is a drawing showing a plan view of wearable patch 200’ that does not include an air gap. FIG. 3A is a drawing showing a cross-sectional view of wearable patch 200 in a non-contracted state and FIG. 3B is a drawing showing a cross-sectional view of wearable patch 200 in a contracted state.

[0039] Patch 200 is depicted as having a round shape, but it should be appreciated that patch 200 may have other shapes such as a rectangular shape, depending on the use case. In some embodiments, wearable patch 200 may have a defibrillation area of at least 50cm2as currently mandated in the applicable standard. In some embodiments, wearable patch 200 may have a minimum defibrillation area according to applicable standards.

[0040] As shown, wearable patch 200 (or simply “patch 200” herein) may include a flexible, stretchable adhesive ring 203 that is also part of a flexible, stretchable outer ring 207, a flexible portion 205 that covers an air gap 202, and a portion of rigid or semi-rigid conductive portion 209. As used herein the term flexible may be understood to include stretchable as well. In some embodiments, flexible portion 205 may cover or may not cover air gap 202.

[0041] As shown, an inner diameter 240 of adhesive ring 203 of the patch may extend underneath a hydrogel conductive interface 201 in order to protect the inner diameter 240 of of adhesive ring 203 from being in contact with the edges of the hydrogel conductive interface 201 that may shift and / or expand due to absorption of skin fluids by the hydrogel during patch usage, to thus prevent peeling off of the adhesive ring 203 from the skin caused by such hydrogel shifting / expansion. Thus, inner diameter 240 is smaller than an outer diameter 242 of hydrogel conductive interface 201.

[0042] Advantageously, flexible portion 205 and air gap 202 enable the rigid or semi-rigid conductive portion 209 to remain in conductive contact with the skin while the flexible, stretchable adhesive ring 203 and outer ring 207 as well as flexible portion 205 flex and stretch as needed due to body movements and related skin movements. As shown in the figures, wearable patch 200may include layers and components as described below, some of which extend between stretchable outer ring 207 and / or flexible portion 205 and / or conductive portion 209.

[0043] A conductive interface 201 may include a conductive hydrogel material and is positioned between the skin of the patient and an electrical conductive layer 204 of patch 200. As above, a portion of adhesive ring 203 extends underneath conductive interface 201 between conductive interface 201 and the skin. Voltages applied or sensed at conductive layer 204 may be conducted through conductive interface 201 to the skin.

[0044] Electrical conductive layer 204 (or simply “conductive layer” herein) may be formed of a conductive material or substrate including but not limited to Ag, Ag-Ag / Cl, stainless steel, aluminum, a semi-rigid printed circuit board (PCB), a flexible PCB, or any other conductive material. In some embodiments, electrical conductive layer 204 may have substantially the same dimensions (such as diameter) as conductive interface 201. In some embodiments, electrical conductive layer 204 may be flexible or semi-rigid.

[0045] Adhesive ring 203 may be configured to adhere to the human body (i.e. to “skin”, as shown in the figures). In some embodiments, adhesive ring 203 may be formed from laminated layers or any other skin adhesive material. In some embodiments, adhesive ring 203 may create a bond with the skin in order to hold the patch in place and prevent adhesive ring 203 from peeling. In some embodiments, as shown, adhesive ring 203 may have a larger outer diameter than outer ring 207. As above, inner diameter 240 of adhesive ring 203 is smaller than an outer diameter 242 of hydrogel conductive interface 201.

[0046] A barrier ring 206 may be positioned and adhered between adhesive layer 203 and a shape cover layer 208. In some embodiments, barrier ring 206 may be formed from foam or another suitably flexible material. Barrier ring 206 may thus add height to outer ring 207.

[0047] In some embodiments, the size of the inner diameter of barrier ring 206 is 0.1 -40mm wider than an outer diameter of conductive interface 201 and electrical conductive layer 204. This difference in diameter creates air gap 202 between the outer diameter of conductive interface 201 / electrical conductive layer 204 and the inner diameter of barrier ring 206. In some embodiments the air gap 202 has a width of between 0. lmm-40mm between the inner diameter of barrier ring 206 and the outer diameter of conductive interface 201 and electrical conductive layer 204. In use, air gap 202 along with flexible portion 205 may compensate for the stretch and contractions of the subject’s skin during a daily routine of patch wearing while ensuring that conductive portion 209 remains in effective contact with the skin.In some embodiments, shape cover layer 208 may be formed from flexible or semi flexible or stretchable material. In some embodiments, shape cover layer 208 may be laminated to barrier ring 206 creating a structure in the shape of the wearable patch. In some embodiments, shape cover layer 208 may have a thickness dictated by the patch design. In some embodiments, an outer diameter of shape cover layer 208 may be substantially the same as an outer diameter of barrier ring 206.

[0048] Conductive layer 204 may be printed onto a substrate layer 210. In some embodiments, substrate layer 210 may have substantially the same dimensions as conductive layer 204. In some embodiments, substrate layer 210 may be flexible or semi-flexible to accommodate the shape of a human body part to which wearable patch 200 is adhered. In some embodiments, shape cover layer 208 may be laminated to substrate layer 210 so as to hold substrate layer 210 in position. In some embodiments, conductive layer 204 may be printed directly onto shape cover layer 208, and substrate layer 210 may not be required.

[0049] In some embodiments, an isolated stiffener layer 212 may be formed of a semi-rigid material such as PET or vinyl. In some embodiments, isolated stiffener layer 212, together with substrate layer 210, ensures sufficient contact of conductive interface 201 to the human body (skin). In some embodiments, the combined thickness of substrate layer 210 and an isolated stiffener layer 212 (described further below) may be 50pm- 1000pm. It should be appreciated that conductive layer 204 (with or without substrate layer 210) may not be sufficiently rigid and isolated stiffener layer 212 provides added stiffness / rigidity to conductive portion 209 to press conductive layer 204 and thus conductive interface 201 onto the skin.

[0050] Patch 200 may be electrically connected to a WCD (not shown) using electrical connection components. The WCD is separate from and may be connected to one or more patches 200 via, for example, an electrical wire 222. The WCD is not mounted on and is not a part of the patch aside from the electrical wire connection thereto. Thus, the WCD is not adhered to the patient, either directly or as part of a patch.

[0051] Electrical wire 222 may be connected to an electrical crimp washer 220 that extends through a metal washer 218, shape cover layer 208, substrate layer 210, and conductive layer 204, before terminating in a conductive eyelet 216 that is in electrical contact with conductive layer 204. In some embodiments, metal washer 218 may prevent conductive layer 204 from bending during the crimping process when crimp washer 220 is crimped into position.In some embodiments, a patch cover layer 214 may seal patch 200 by being adhered to shape cover layer 208 and isolated stiffener layer 212 over conductive portion 209, and to extend over shape cover layer 208 and over air gap 202 to create flexible portion 205. In some embodiments, an outer diameter of patch cover layer 214 may be substantially the same as an outer diameter of barrier ring 206. In some embodiments, patch cover layer 214 may be water resistant or water proof, or non-water resistant according to the required design. In some embodiments, patch cover layer 214 may be made of a flexible material such as thermoplastic polyurethane (TPU). Patch cover layer 214 may include adhesive to be adhered to and hold in position within patch 200 isolated stiffener layer 212 as well as electrical connection components 216, 218, 220, and 222.

[0052] As shown, flexible portion 205 may include layers / components 208+214, outer ring 207 may include layers / components 203+206+208+214, and conductive portion 209 may include layers / components 201+204+210+208+212+214.

[0053] As shown in FIG. 2D, wearable patch 200’ may include a flexible, stretchable adhesive ring 203, and a rigid or semi-rigid conductive portion 209. Patch 200’ is similar to patch 200 but does not include an air gap.

[0054] As shown, an inner diameter 240 of adhesive ring 203 of the patch may extend underneath a hydrogel conductive interface that is part of conductive portion 209 in order to protect the inner diameter 240 of of adhesive ring 203 from being in contact with the edges of the hydrogel conductive interface that may shift and / or expand due to absorption of skin fluids by the hydrogel during patch usage, to thus prevent peeling off of the adhesive ring 203 from the skin caused by such hydrogel shifting / expansion. Thus, inner diameter 240 is smaller than an outer diameter 242 of hydrogel conductive interface 201.

[0055] FIG. 3A shows WCD patch 200 with flexible portion 205 in a stretched state (and air gap 202 uncompressed) such as when the skin and adhered adhesive ring 203 move in a direction shown by arrow “A” while conductive interface 201 remains in contact with the skin. FIG. 3B shows WCD patch 200 with flexible portion 205 in a contracted state (and air gap 202 compressed) such as when the skin and adhered adhesive ring 203 move in a direction shown by arrow “B” while conductive interface 201 remains in contact with the skin. It should be appreciated that skin movement results in contraction and expansion of flexible portion 205 over air gap 202 while conductive interface 201 remains in contact with the skin.Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0056] In the claims or specification of the present application, unless otherwise stated, adjectives such as “substantially” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended.

[0057] It should be understood that where the claims or specification refer to "a" or "an" element, such reference is not to be construed as there being only one of that element.

[0058] In the description and claims of the present application, each of the verbs, "comprise" "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb.

[0059] While this disclosure describes a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of such embodiments may be made. The disclosure is to be understood as not limited by the specific embodiments described herein, but only by the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A wearable cardioverter defibrillator (WCD) patch, comprising:an adhesive ring configured to be adhered to skin of the subject; anda conductive portion including a conductive hydrogel interface,wherein the adhesive ring has an inner diameter smaller than an outer diameter of the conductive hydrogel interface, and wherein the WCD is a long-term WCD for continuous wearing by a patient.

2. The WCD patch of claim 1 , configured such that conductive portion remains in conductive contact with the skin while the adhesive ring flexes and stretches as needed due to body movements and related skin movements of the patient.

3. The WCD patch of claim 1, configured for adhesion to the patient for at least one day.

4. The WCD patch of claim 1, wherein the adhesive ring has adhesive configured to adhere to human skin.

5. The WCD patch of claim 1, wherein the wearable patch has a defibrillation area of at least 50cm2or the minimum area according to applicable standards.

6. The WCD patch of claim 1, wherein a WCD is separate from and connected to the WCD patch via an electrical wire.

7. The WCD patch of claim 1, wherein a WCD is not mounted on and is not a part of the WCD patch aside from an electrical wire connection thereto.

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