WO2011039329A1

WO2011039329A1 - An adhesive patch for monitoring acoustic signals

Info

Publication number: WO2011039329A1
Application number: PCT/EP2010/064600
Authority: WO
Inventors: Claus Bo Vöge CHRISTENSEN; Weimin Rong; Carsten Thirstrup
Original assignee: Acarix A/S
Priority date: 2009-09-30
Filing date: 2010-09-30
Publication date: 2011-04-07

Abstract

An adhesive patch for monitoring acoustic signals from a human or animal body, comprising an acoustic sensor for detecting body sounds and skin contact surface adapted to cover a part of a skin surface of a human or animal body. The skin contact surface comprises an adhesive element for attaching the patch to the skin surface and at least one release liner, wherein the release liner is adapted to be removed from the skin contact surface while at least a part of the skin contact surface covers the skin surface and the patch maintains its position on the skin surface.

Description

An Adhesive Patch for Monitoring Acoustic Signals

Cross-reference to Related Applications

The present application claims the benefit of Danish patent application No.

2009/70136, filed 30 September 2009, which is incorporated herein by reference.

Technical Field

The present invention relates to the field of adhesive patches, which can detect and record acoustic signals from the body.

Background Art

Coronary artery disease (CAD) is a continuously increasing threat to the public health globally, where tobacco smoking, increased stress, lack of exercise, fat saturated diets, obesity, and so on, are reported to be significant direct or indirect risk factors for the development of blockages in the coronary arteries, resulting in coronary artery disease. Currently, the present methods for assisting in the diagnostics and/or diagnosis of CAD are expensive and require complicated equipment, such as an electrocardiogram, nuclear scanning, CAT scans and MRI scans or invasive methods like angiography or coronary angiography.

Furthermore, these methods require that the subject spend a considerable amount of time in hospital laboratories.

The execution of the previously mentioned methods may be very expensive, which means that the methods are rarely used for preventive diagnostics and subjects are usually subjected to CAD diagnostics subsequent to physical problems indicating the presence of CAD, such as chest pains, and so on.

Therefore, there is a need for an improvement in monitoring the physical signs of CAD, using acoustic signals from the human or animal body, where the acoustic signals are selectively or continuously recorded and/or transmitted to a peripheral device. It has been shown during testing of acoustic patches that if the acoustic recordings are obtained while the converting means are held in position by the user or a healthcare professional, which often is done using an analog or digital stethoscope, the converting means collect a mechanical noise which is caused by minute vibrations originating from the hand or the human extremity which holds it in place. Although it appears that some people have a very steady hand, it is physically impossible to remove all vibrations as skeletal muscles are stimulated using periodical nerve signals, which cause very small vibration in the muscle as each muscle fiber contracts.

The vibration caused by the hand becomes a significant noise factor when the converting means are held in position using the arm and/or the hand for recording the acoustic signals from the body and the converting means are very sensitive and capable of recording extremely vague signals. This type of noise can be reduced drastically using an embodiment where the converting means are adhered to the skin surface using an adhesive patch, such that the converting means are not affected by vibrations in the hand of the medical professional.

It should be understood that the term 'acoustic' should be interpreted broadly as a difference, typically a change, in pressure, which for example is conveyed through the air and/or the human or animal body from a target area, for example a coronary artery, to a detecting unit, for example the human ear or the converting means. For example the above described mechanical noise caused by minute vibration originating from the hand is not audible to the human ear without being processed, for example by amplification and/or frequency manipulation.

Another advantage of adhering the converting means to the skin surface is that the user can wear the adhesive patch for a longer period of time, such that acoustic signals may be recorded over a longer time period, if deemed necessary for diagnostic purposes. An example of a device for monitoring an acoustic signal is disclosed in WO 2009/080040, comprising an adhesive patch containing an acoustic patch. The adhesive patch is provided with an adhesive layer on the skin contact surface, where the adhesive layer ensures that the patch stays in place after it has been placed onto the skin surface of a user.

Another acoustic patch is disclosed in WO 08/068695. The patch is a handheld, repositionable ECG detector. A release liner covers and protects a hydrogel prior to use and can be removed to expose the hydrogel. A second release liner is removed to expose a pressure sensitive adhesive by means of which the device is attached to a subject. The first and second release liners may be parts of a single release liner layer. Prior to attachment to the patient, the monitoring device may be pressed against the patient to locate a good site for ECG measurements or to quickly monitor the ECG. The monitoring device may be repositioned at this time until a good measuring site is found. Once an appropriate location is found for attachment of the patch, a location on the body where a clear ECG signal is received, the release liner is peeled away and the patch is attached in place by the pressure sensitive adhesive. An acoustic patch is used to pick up body sounds and convert it to the electronic signals. The CAD system records acoustic signals. Good electrical contact (as in electrically conducting adhesive) is not a prerequisite for signal transmission. However patients may be shaved to avoid hair removal by adhesive removal and to reduce friction noise.

The positioning of the acoustic patch can be visualised on an appropriate screen by the ratio of S1/S2 heart signals, but in lack of proper display equipment also heard by the trained physician. A good acoustic contact is therefore needed, free from background and friction noises. Hair may in this case contribute to friction noise. Since the recording is very sensitive to placement, the optimal placement has to be pursued in every case. As a general rule the Intercostal area 4 region is the area of interest, however, fine tuning of the placement within the Intercostal area 4 region is important, with respect to whether placement should be closer to the sternum or further away from the sternum. To determine this in the absence of a display device, a good sound quality is important. A good sound quality can be obtained by reducing noise from friction, using for example gel or other sound conducting media, while investigating the optimal placement. Summary

One object of the present invention is to be able to position and apply an acoustic patch accurately to a skin surface.

Brief Description of the Drawings

The invention is disclosed more in detail with reference to the drawings in which

Figure 1 a shows a patch seen from the skin facing side,

Figure 1 b shows a cross-section of the patch of Figure 1 a,

Figure 1 c shows a cross-section of another embodiment of a patch,

Figure 2 shows positioning and application of a patch,

Figures 3-5 show different embodiments of a patch, and

Figure 6 shows a method of applying an acoustic patch.

Detailed Description

The invention relates to an adhesive patch for monitoring acoustic signals from a human or animal body, comprising

a) An acoustic sensor for detecting body sounds,

b) a skin contact surface adapted to cover a part of a skin surface of a

human or animal body comprising

• an adhesive element for attaching the patch to the skin surface, · at least one release liner,

• wherein the release liner is adapted to be removed from the skin contacting surface while at least a part of the skin contact surface covers the skin surface and the patch maintains its position on the skin surface.

The acoustic sensors of the patch may be covered by a sliding film, the film providing a low friction surface between the sensors and the skin during positioning of the patch, thus facilitating easy sliding of the patch over the skin. The sliding film covering the skin-facing surface of the acoustic sensors allows the user to easily move the patch on the skin for optimization of the detection location where the acoustic patch may pick up the maximum response signal.

The skin contact surface may be provided with an acoustic window over the acoustic sensor. An acoustic film, made from an impedance matched polymer film such as a polyurethane polymer may be covering the acoustic window in the patch, allowing for precision placement relative to the desired sound source.

The release liner may be provided with an aperture for accommodating the acoustic window, thereby leaving the acoustic window uncovered by the release liner and allowing the sound conducting media to remain in contact with the skin while positioning the patch. Thus, the release liner may not contribute to noise and thereby blur the acoustic signal.

The skin contacting surface of the patch may be provided with a low friction surface. This may ease the sliding of the patch over the skin as well as it may reduce noise of the sliding action. Such noise may disturb the detection of acoustic signal.

The acoustic window may be provided with an adhesive layer. In this case, the release liner may cover the acoustic window. The acoustic patch comprises an acoustic sensor and an adhesive element for attaching the patch to a skin surface. The acoustic sensor is located on top of the adhesive element and the skin facing surface of the adhesive element is covered by at least one release liner. Once the release liners are removed and the adhesive is applied to the skin, the acoustic patch cannot be moved anymore.

After optimization of the patch's detection location, the release liners covering the adhesive surface can be peeled off without removing the patch from the skin and thereby avoiding the risk of dislocation of the patch. At least part of the skin contact surface may be in physical contact with the skin while the release liner is removed. Acoustic patches known in the art may be provided with one release liner covering the entire adhesive surface of the patch. When the optimal position of the patch is detected, the location is marked, and the patch lifted away from the skin in order to be able to remove the release liner. Then the patch is applied at the location according to the marking. However, applying to the correct position after having been removed may be difficult. The correct position may be marked with a pen, which is laborious and comprises an additional step in the process, or the position may be marked by for example holding a finger at the spot, leaving a hand less for removal of the release liner. Alternatively, the release liner is removed before positioning the patch, but this will make positioning difficult, due to the friction and tackiness of the adhesive surface.

The release liner of the patch is adapted to be removed from the skin contacting surface while at least a part of the skin contact surface covers the skin surface and the patch maintains its position on the skin surface. Thereby it is easier to apply the patch accurately at the desired location, avoiding the risk of dislocating the patch during removal of the release liner.

The release liner of the patch of the invention is intended to remain at the adhesive surface of the patch during detection of the optimal location for picking up an acoustic signal. When the location is found, the release liners are peeled off, one by one, still holding the patch towards the skin and in the correct position. In this way, the patch will remain in correct location from the moment the position is detected until the patch is fastened by the adhesive.

The patch may comprise one release liner. The release liner may be cut in helix shape which can be removed by unwinding or it may be folded to produce a rolling movement during detachment from the adhesive surface.

The patch and the acoustic recording device may be assembled prior to use, thereby activating the device to sound recording during placement.

The skin contact surface may comprise two or more release liners. The release liners each cover a section of the adhesive surface. The release liners are arranged so as to enable removal of them while having at least a part of the skin contact surface held towards the skin surface. Pressing the patch against the desired location of the skin surface and at the same time removing the release liners, render it possible to apply the patch exactly at the correct location, without moving the patch in proportion to the skin surface for detaching of the release liners. In order to ease grabbing of the release liner, the liner may be provided with one or more tab members extending over the edge of the patch. Such tab members may be easy to grab and pull when the release liner is to be separated from the adhesive surface. Two release liners may cover each half of the adhesive surface of the patch. Thereby half of the adhesive surface of the patch is exposed when the first release liner is removed. The exposed adhesive surface can be attached to the skin when the recording position has been identified. Then the second release liner covering the other half of the adhesive surface is removed, and the acoustic patch is fully applied to the skin at the desired location. The release liner may be folded. The first part of the liner may be attached to the adhesive, and a second part may be superimposed over the first part. Thereby the release liner may be detached from the adhesive surface by pulling the superimposed part in a substantially parallel direction away from the fold line.

In an embodiment of the invention, the patch comprises at least two release liners, a first liner exposing a small area of the adhesive layer when removed, and a second liner covering the residual surface of the adhesive layer. The first liner may be removed first, thereby securing the position of the patch to the skin. Subsequently, the second liner is removed and the patch is adhered to the skin at the correct location.

The invention also relates to a method of applying an acoustic patch to the skin for detection of body sounds comprising the following steps:

a) obtaining an adhesive patch for monitoring acoustic signals from a human or animal body, the patch comprising an acoustic sensor for detecting body sounds, and a skin contact surface adapted to cover part of the skin surface of a human or animal body, said surface comprising an adhesive element for attaching the patch to the skin surface and at least one release liner,

b) locating an optimal detection location of the acoustic patch on the skin surface in order to obtain a maximum response signal by sliding the patch over the skin surface until an optimal signal is achieved,

c) maintaining the acoustic patch at the optimal detection location at the skin surface,

d) removing the release liner, thereby attaching the patch adhesively to the skin, and

e) detecting body sounds by the acoustic patch. Description of Embodiments

The invention is now explained more in detail with reference to the drawings showing preferred embodiments of the invention. In Figure 1 a and 1 b is shown an embodiment of an acoustic patch 1 , where Figure 1 b is a cross sectional view along line A of Figure 1 . The acoustic patch 1 comprises a microphone 2 for detecting body sounds, an adhesive (adhesive element) 3 for attaching the patch 1 , and a small release liner 4a and a large release liner 4b covering an adhesive surface 8 of the patch 1. Over the microphone 2 is an acoustic window 5 having a low friction surface. A tab member 7 extending further than a border of the acoustic patch 1 may be present in order to facilitate easy handling. The tab member 7 is non-adherent.

Specifically, the microphone 2 forms an acoustic sensor that can detect sound from a human or animal body. For proper detection the acoustic window 5 is provided over the microphone 2 and contact elements 6 provide connection points to a signal processing equipment 102 that can receive and use signals from the microphone 2. An acoustic window 5 defines, as is known, a section or element where sound shall be received for subsequent detection by the microphone 2. The microphone 2 and the acoustic window 5 may per se be implemented according to known techniques within the field of medical signal processing.

The microphone 2 is embedded in a main body 31 of the acoustic patch 1 . The main body 31 has a surface 8 that forms an underside of the main body 31 , and the surface 8 is covered with the adhesive such that the surface form an adhesive surface and the acoustic patch 1 may be attached to a skin surface 101 of a human or animal body. Preferably but not necessarily the microphone 2 protrudes from the main body 31 in a direction towards the skin surface 101 . In detail, the microphone 2 may protrude a distance D1 towards the skin surface 101 as compared with a section 34 of the main body 31 that is close to the microphone 2. This also means that the microphone protrudes from at least a part of the surface 8. The main body 31 and hence its underside surface 8 has a circumference, or border, that is defined by a peripheral edge which is illustrated by peripheral sections 81 and 82. The "small" and "large" release liners 4a and 4b can be seen as a first release liner 4a and a second release liner 4b, and can have different, relative sizes but also equal sizes. The release liners 4a, 4b form in combination a liner 4 that covers the underside surface 8 and protects the adhesive 3.

The second liner 4b is in this embodiment larger than the first liner 4a and thus covers a relatively larger section of the underside surface 8. An aperture 93 is provided in the second liner 4b at a position of the acoustic window 5, such that the acoustic window 5 can be accommodated, i.e. the acoustic window 5 is in this embodiment not covered by the liner 4. The second liner 4b comprises a first section 91 that abuts to the underside surface 8 and a second section 92 that in this embodiment is folded over the first section 91 . Thus, the liner 4 which comprises the second liner 4b is folded, and it can be said that the first section 91 forms a first folded part of the liner 4 that is attached to the adhesive element 3, while the second section 92 forms a second folded part that is superimposed over the first folded part 91 .

The second section 92 is provided with a tab member 7 that extends over peripheral section 81 by a predetermined distance D2. The tab member 7 may be seen as an integral part of the second liner 4b. The peripheral section 81 can here be seen as an edge of the acoustic patch 1 .

The first liner 4a comprises a first section 41 that abuts to the underside surface 8 and a second section 42 that is folded over the first section 41 . Thus, the first liner 4a is folded in manner similar with the second liner 4b, and the first section 41 forms a first folded part of the first liner 4a and is attached to the adhesive element 3, while the second section 42 forms a second folded part that is superimposed over the first folded part 41. Additionally, the first liner 4a comprises a section 43 that coves a part of the second liner 4b, as can be seen in Fig 1 b. Alternatively, the second liner 4b may comprise a corresponding section that covers a part of the first liner 4a. The first section 41 of the first liner 4a is provided with a tab member 71 that extends over peripheral section 82 by a predetermined distance, in a manner corresponding to the tab 7 of the second liner 4b. The peripheral section 82 can also be seen as an edge of the acoustic patch acoustic patch 1 , and the tab member 71 may be seen as an integral part of the second liner 4b.

With reference to Figure 1 c another embodiment of an acoustic patch 1 is illustrated where the liners 4a, 4b have equal sizes. In this case the liners 4a, 4b are folded symmetrically over the surface 8. Figure 2 shows positioning of the acoustic patch 1 for optimized acoustic response, by sliding (a) the patch over the body part until optimal signal is received, which may be transmitted wirelessly; and then the release liner 4 is removed (b) without changing the position of the patch. This illustrates a major difference from known acoustic patches, which are unable to facilitate removal of a liner while the patch is still securely positioned on a skin surface. In detail, the present acoustic patch 1 may be firmly positioned with the underside surface 8 arranged at the skin surface 101 while the liner 4 still is in place, i.e. with the liner 4 is in-between the underside surface 8 and the skin surface 101 . Since the tabs 7, 71 protrude at the edges 81 , 82 of the acoustic patch 1 it is possible to remove a liner by pulling its tab, while still holding the acoustic patch 1 firmly against the skin surface 101 . When the tab is pulled, the corresponding liner "rolls of" the adhesive on the underside surface 8. The adhesive covered by the removed liner then comes into contact with the skin surface 101 and attaches the acoustic patch 1 to the skin surface 101 . A remaining tab can then be removed, while still pressing the acoustic patch 1 against the skin surface 101 . After removal of the remaining tab the whole underside surface 8 is attached to the skin surface 101 by virtue of the adhesive 3. This solves the problem of how to provide more efficient and/or accurate positioning of an acoustic patch. Any of the liners 4a, 4b can be removed first, but it is often advantageous to remove a smaller liner before removing a relatively larger liner. From above follows that the release liner 4 may be configured to be removed from the patch when the patch is located on the skin surface 101 , which is one major difference from known acoustic patches. The method of positioning and/or applying the acoustic patch 1 has been further elucidated in Figure 6, where a first step 601 comprises obtaining the acoustic patch 1 , for the purpose of monitoring acoustic signals from a human or animal body. The acoustic patch 1 may be configured as described above, i.e. may comprise i) the acoustic sensor 2 for detecting body sounds, ii) the skin contact surface 8 adapted to cover a part of the skin surface 101 of a human or animal body, where the surface 8, or in more general terms the acoustic patch 1 , comprises an adhesive element 3 for attaching the patch 1 to the skin surface 101 , and iii) the at least one release liner 4. In a next step 602 an optimal detection location of the acoustic patch 1 is located on the skin surface 101 in order to obtain a maximum response signal. This is done by sliding the acoustic patch 1 over the skin surface 101 until an optimal signal is achieved. In a next step 603 the acoustic patch 1 is maintained at the optimal detection location at the skin surface 101 , in a following step 604 the release liner 4 is removed which thereby attaches the acoustic patch 1 adhesively to the skin surface 101 , and in a final step 605 body sounds are detected by means of the acoustic patch 1 . Steps 602 and 605 employs the processing equipment 102 for obtaining a maximum response signal and detecting body sounds, and may per se be performed according to known principles and methods.

Figure 3 disclose an embodiment of an acoustic patch 1 wherein the release liners 4a, 4b are folded leaving one part of the liner attached to the adhesive surface and a second part superimposed over the first part. The fold line of the release liner is located centrally of the patch (corresponding to Figure 1 c) and abut the fold line of the other release liner (a). The second part may be elongated further than the first part in order to provide a tab member, serving as an easy grip handle. Pulling (b) the tab member away from the centre of the patch, while holding the patch in position against the skin, the release lines will roll off the adhesive, and the patch is applied (c).

Figure 4 discloses another embodiment of the invention wherein a handle 201 is attached to or is a part of the edge of one release liner 4a adjoining the other release liner 4b. The handle 201 extends over the edge of the acoustic patch 1 . When the handle 201 is pulled away from the adjoining line, the release liner is rolled off.

In Figure 5 is disclosed a patch with four release liners 4a, 4b, 4c, 4d (a), where the release liners may be folded as described in connection with previous figures. Two small release liners 4c and 4d are located on each side of the acoustic window. Two large release liners 4a and 4b, respectively cover the remaining of the adhesive.

The release liners described above have a low friction sliding surface towards the skin of the human being or animal, and the acoustic patch can readily be positioned for optimized body signal detection. After the positioning of the acoustic patch, the release liners 4a and 4b are removed (b), essentially without changing the position of the acoustic patch, and the exposed adhesive parts are then attached to the skin of the human being or animal, and the patch has been positioned at an optimized position.

For the embodiment of Figure acoustic window 5, as the last step in the attachment of the patch, the remaining two release liners 4c and 4d can now be removed (b) without changing the position of the patch, and the rest of the adhesive can be attached to the skin. Note that during the last step in the positioning, the adhesive may be bended without affecting the position of the patch in relation to the skin area, from where the acoustic patch detects body signals.

Claims

1 . An adhesive patch for monitoring acoustic signals from a human or animal body, the adhesive patch comprising

an acoustic sensor (2) for detecting body sounds;

a skin contact surface (8) adapted to cover a part of a skin surface (101 ) of a human or animal body,

an adhesive element (3) for attaching the patch to the skin surface (101 ), at least one release liner (4), wherein the release liner (4) is adapted to be removed from the skin contact surface (8) while at least a part of the skin contact surface (8) covers the skin surface (101 ) and the patch maintains its position on the skin surface (101 ).

2. The patch according to any of the preceding claims, wherein the release liner (4) comprises a first release liner (4a) and a second release liner (4b).

3. The patch according to any of the preceding claims, wherein the release liner (4a) is folded and a first folded part (41 ) of the liner (4a) is attached to the adhesive element (3) and a second folded part (42) is superimposed over the first folded part (41 ).

4. The patch according to any of the preceding claims, wherein the release liner (4) is provided with a tab member (7) extending over an edge (81 ) of the patch.

5. The patch according to claim 4, wherein the tab member (7) extends over the edge (81 ) of the patch by a predetermined distance (D2).

6. The patch according to claim 5, wherein the predetermined distance (D2) is at least 10 mm.

7. The patch according to any of the preceding claims, wherein the release liner (4) is configured to be removed from the skin contact surface (8) when the release liner (4) abuts against the skin surface (101 ).

8. The patch according to claim 2, wherein the first release liner (4a) is configured to be removed from the skin contact surface (8) when both the first release liner (4a) and the second release liner (4b) abut against the skin surface (101 ).

9. The patch according to any of the preceding claims, wherein

the acoustic sensor (2) is configured to transmit a signal representing a proper position of the patch, and

the release liner (4) is configured to be removed from the patch when a signal representing a proper position of the patch is transmitted from the acoustic sensor (2).

10. The patch according to any of the preceding claims, wherein the acoustic sensor (2) protrudes from the skin contact surface (8).

1 1 . The patch according to any of the preceding claims, wherein the release liner (4) is provided with an aperture (93) for accommodating an acoustic window (5).

12. A method for applying an acoustic patch (1 ) for detection of body sounds, the method comprising:

- obtaining (601 ) the acoustic patch (1 ) for monitoring acoustic signals from a human or animal body, the acoustic patch (1 ) comprising an acoustic sensor (2) for detecting body sounds, and a skin contact surface (8) adapted to cover a part of the skin surface (101 ) of a human or animal body, said surface (8) comprising an adhesive element (3) for attaching the acoustic patch (1 ) to the skin surface (101 ) and at least one release liner (4),

- locating (602) an optimal detection location of the acoustic patch (1 ) on the skin surface (101 ) in order to obtain a maximum response signal by sliding the acoustic patch over the skin surface (101 ) until an optimal signal is achieved,

- maintaining (603) the acoustic patch (1 ) at the optimal detection location at the skin surface (101 ),

- removing (604) the release liner (4), thereby attaching the acoustic patch (1 ) adhesively to the skin surface (101 ), and

- detecting (605) body sounds by means of the acoustic patch (1 ).