Source: https://patents.google.com/patent/CA2709637C/en
Timestamp: 2019-06-27 11:26:24
Document Index: 171467098

Matched Legal Cases: ['art 31', 'art 32', 'art 31', 'art 31', 'art 32', 'art 32', 'art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art 31', 'art.\n4']

CA2709637C - An adhesive patch for monitoring acoustic signals - Google Patents
An adhesive patch for monitoring acoustic signals Download PDF
CA2709637C
CA2709637C CA2709637A CA2709637A CA2709637C CA 2709637 C CA2709637 C CA 2709637C CA 2709637 A CA2709637 A CA 2709637A CA 2709637 A CA2709637 A CA 2709637A CA 2709637 C CA2709637 C CA 2709637C
CA2709637A
CA2709637A1 (en
2007-12-20 Priority to DKPA200701831 priority Critical
2009-07-02 Publication of CA2709637A1 publication Critical patent/CA2709637A1/en
2016-10-04 Publication of CA2709637C publication Critical patent/CA2709637C/en
An adhesive patch for monitoring acoustic signals from a human or animal body, comprising a skin contact surface, converting means for recording the acoustic signals and converting it to a first electric output signal, and an adhesive element for attaching the converting means to the skinsurface, the patch further comprises transmitting means for transmitting the output signal to a peripheral device.
An Adhesive Patch for Monitoring Acoustic Signals FIELD OF THE INVENTION
Coronary artery disease (CAD) is a continuously increasing threat to the public health in western society, where tobacco smoking, increased stress, lack of exercise, fat saturated diets, obesity, etc. 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, angiography or coronary angiography, CAT scans and MRI scans.
Furthermore, these methods require that the subject spend a considerable amount of time in hospital laboratories.
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. The selective
2 transmission means that normal signals would not be transmitted while abnormal signals could trigger a transmission.
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. It has been shown during testing of one embodiment 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.
3 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, e.g. 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, e.g. by amplification and/or frequency manipulation.
The acoustic signals are recorded by placing the converting means, or the microphone, in direct contact with the skin surface of the user or by positioning an acoustic conducting layer between the converting means and the skin surface, the acoustic conducting layer functioning as a means for sound propagation. It has been discovered that any change in pressure between the converting means and the skin surface, may influence and/or reduce the transmission of the sound between the skin surface and the converting means.The acoustic conductivity, transmission and/or contact between the conducting means and the skin surface is optimized by maintaining the pressure between the converting means and the skin surface as stable as possible, i.e. that the pressure does not vary significantly during
4 the use time of the adhesive patch or that the pressure applied is significantly higher than any variation in pressure.
When the skin contacting surface of the adhesive patch is placed on the skin, the protrusions apply an increased pressure onto the areas of the skin which are in contact with the protrusions and inside the area that is defined by the protrusions. This means that while the skin contacting surface of the adhesive patch maintains its contact with the adhesive patch, the skin surface inside the area defined by the protrusions maintains an increased tension. The tension of the skin surface does not vary significantly when the user moves or changes his/her posture as the compression structure maintains the tension of the skin inside the area defined by the protrusions. Within the skin contacting area defined by the area in a inwards radial direction from the protrusions, an acoustic medium can be applied to increase the the tension at the skin surface further.
5 Another means for managing the pressure between the converting means and the skin surface may be to position the converting means inside a pressure cavity arranged in the adhesive patch. The skin contacting surface of the adhesive patch operates as the gas and/or liquid impermeable barrier between the adhesive patch and the skin surface. The pressure cavity may comprise an external wall which creates a gas- and/or liquid impermeable barrier to the atmosphere, which ensures that any gas or liquid contained or introduced into the cavity may be sealed inside the cavity. The adhesive patch may be provided with a one and/or two way valve which may be used to introduce or remove gas and/or liquids into the cavity to manage the pressure inside the cavity. The converting means may be placed inside the pressure cavity providing a direct or indirect contact with the skin surface of the user, where the pressure inside the cavity would ensure that any movement or change in the user's posture would not alter the pressure between the converting means and the skin surface. In one embodiment of the present invention the patch may further comprise processing means for processing the first electric output signal and converting it to at least a second electric output signal. For this purpose, the patch may be provided with processing means in the form of a microprocessor, microcontroller, A/D
converter, digital signal processor and/or the necessary electrical circuitry such that the acoustic recording may be partly processed within the adhesive patch into a second electric output signal.
The term fully processed acoustic signal means in the context of the present application an acoustic signal that has been fully processed within the adhesive patch, such that all signal-processing steps, which are deemed necessary to provide an indication of an abnormal signal, are taken. The signal processing steps are similar to the abovementioned steps defined in context of the partly processed acoustic signal. Additionally, the fully processed
6 signal has been processed into values or a mathematical representation, which may be compared to standard values or fed into a mathematical model such that the processing means can be instructed to indicate if there are some unusual elements in the recorded acoustic signal.
In one embodiment of the present invention the converting means may include at least one microphone, where the microphone is used to record the acoustic signals from the body.
The microphone produces the first electrical output signal which may be stored within the adhesive patch, transmitted to a peripheral device, processed and/or analysed within the adhesive patch. In another embodiment of the present invention the converting means may include at least two microphones, where the first microphone is used to record the acoustic signals from the body and the at least second microphone is used to record environmental noise signals. By using two microphones, which are recording acoustic signals synchronously, the noise signal acquired from the second microphone can be used to remove the environmental noise recorded by the first microphone, which ideally reduces the noise level significantly and the remaining acoustic signal is the primary acoustic signal from the body, which is interesting for the diagnostic procedure.
A number of different types of microphones may be used for the purpose of recording acoustic signals from the body, where in one embodiment the at least one microphone may
7 be a silicon microphone and in another embodiment the at least one microphone may be a pressure sensitive contact microphone. In alternative embodiments of the present invention where the adhesive patch includes more than one microphone, the microphones may be of different types. This might be advantageous as one type of microphone might be better suited for noise recording and another type might be better suited for the recording of acoustic signals from the body. It is obvious to the skilled person based on the teachings of the present invention that any type of microphone suited for recording noise, acoustic signals from the body or similar might be used in the adhesive patch of the present invention.
8 In one embodiment of the present invention the acoustic absorbing layer may comprise a high-density material, such as a hydrocolloid material, where the hydrocolloid material may be a layer of the adhesive patch or an integral part of the adhesive patch.
The isolating capabilities of the hydrocolloid material are dependent on the thickness and the chemical composition of the material, where a thicker material isolates more than a thin material and material containing high-density particles might dampen the noise and provide increased isolation. The hydrocolloid material is permeable to water vapor, which means that any water vapor introduced into the adhesive patch from the skin surface may escape the patch through the hydrocolloid layer. The water vapor permeability of the hydrocolloid material may protect the electrical circuitry within the patch such that the risk of moist damage to the electrical compounds is reduced.
In one embodiment of the present invention, the acoustic conducting layer may be formed of an acoustic conducting material that may be provided as a coating that envelopes at least a part of an external surface of the converting means. The acoustic conducting material may be in the form of a solid layer enveloping a part of the external surface of the converting means or the entire external surface of the converting means. Advantageously, the acoustic
9 conducting material covers at least the external area of the converting means that is suitable for acquiring the acoustic signal from the body.
The acoustic conducting material may envelope the entire external surface of the converting means, where the acoustic conducting material provides an increased acoustic conductivity between the converting means, the skin surface and the acoustic conducting material.
Furthermore it may be used to protect or shield the converting means from any harmful contaminants that may reduce the lifespan of the converting means or may reduce the converting means capability to record acoustic signals from the body, such as particles, moisture and other contaminants that may be considered as harmful.
In one embodiment of the present invention the adhesive patch may further comprise visual means for indicating placement of the adhesive patch according to anatomic landmarks on the human or animal body. The visual means may be used to facilitate the positioning of the adhesive patch according to predetermined anatomic landmarks, where the anatomical landmarks are dependent on what acoustic monitoring task is being performed.
This means that the physical positioning of the patch may facilitate for a specific type of acoustic monitoring task. This might also be important in the case were the acoustic patch has more than one converting means for recording acoustic signals from the body, for example an 1 D, 2D or 3D array of converting means and the exact placement and the spatial positioning of the array is important or even vital for the outcome of the acoustic recording, depending on the application of the adhesive patch.
The present invention further describes a method for monitoring acoustic signals from the human body using an adhesive patch comprising converting means, processing means and transmission means. The adhesive patch is positioned on the skin surface of a user, such that the converting means are in direct or indirect communication with the skin surface. The converting means convert the recorded acoustic signals into an analog electrical signal, which in turn is converted into digital form using an A/D converter. In order to be able to reduce the size of the analog or digital signal, the signals are filtered using a bandpass filter having a predefined upper and lower frequency limit. The predefined upper and lower frequency limits are chosen based on what acoustic signals in the body are being monitored.
In one embodiment of the present invention where the converting means comprise two microphones and the first microphone records acoustic signals from the body and the second records noise, the two resulting signals may be fed into a differential amplifier. The differential amplifier compares the input signals and reduces the magnitude of the first microphone signal by the magnitude of the synchronous second microphone signal. This results in the reduction of noise in the first microphone signal, which means that the underlying acoustic signal from the body becomes clearer in the output signal of the differential amplifier.
At any point in time, from the acquisition of the acoustic signals using the converting means, may the resulting signals be stored in a memory bank, such as flash memory or be transmitted to a peripheral device. The choice of at which point in time storage or transmission is performed may be taken by a technician or a medical professional.
Furthermore, the transmitting means may be used to program the adhesive patch and provide the patch with appropriate instructions for each monitoring task.
The invention will now be described in further detail below with reference to the schematic drawings in which, Fig. 1 is an exploded view of an adhesive patch for monitoring acoustic signals from the body according to the present invention, and Fig. 2 is a sectional view of the same taken along line II-II in Fig. 1 Fig. 3 is a sectional view of an adhesive patch comprising a adhesive part and a separate converting part, Fig. 4a and 4b are sectional views of adhesive parts having compression structures, and Fig. 5 is a sectional view of an adhesive patch according to the present invention applied on the skin surface of a user.
A microphone 5 is positioned on the inner surface, i.e. the surface that is adjacent to the adhesive layer 4, of the projection area 3. This microphone 5 has, in this embodiment, direct access to the skin surface of the subject, where none of the patch layers separate the microphone and the skin surface when the adhesive patch 1 is adhered to the skin surface.
This can be seen as the adhesive layer has an opening in the central area, which corresponds in size to the projection area 3. Furthermore, on the inner surface of the projection area 3, between the protective layer 2 and the microphone 5 a pad 6 or block of resilient material is placed, which provides support to the microphone 5. The resilient pad 6 ensures that the microphone is optimally pressed to the skin surface when the patch adhered on the skin surface of the user. The choice of resilient material for the pad 6 may be varied, such that the contact between the skin surface and the microphone is always at an optimal pressure in different situations.
Fig. 2 shows a sectional view of the adhesive patch 1 taken along line II-II
in Fig. 1, where the different parts of the adhesive patch are assembled. It can be seen in this assembled state that the first microphone 5, protrudes from a plane defined by the adhesive layer 4, such that when the patch is adhered to the skin surface, the microphone becomes depressed into the skin surface and the resilient pad 6 and the pad 6 provides optimal pressure between the first microphone 5 and the skin surface.
Fig. 3 shows a schematical view of one embodiment of an adhesive patch 30 according to the present invention where the adhesive part 31 and the converting part 32 may be releasably connected to each other via a first connecting means 33 and a second connecting means 34. The adhesive part 31 is provided with an adhesive surface providing the skin contacting surface and a non-adhesive outer surface 36 which faces away from the skin contacting surface 35. The adhesive part has a through-going opening 37 which provides communication from the outer surface 36 of the adhesive part 31 to the skin contacting surface 35.
The converting part 32 comprises a housing 38 having a cylindrical wall 39 and a back wall 40 where the walls define an inner cavity 41 housing a pressure management element 42, in the form of resilient foam or similar material, and converting means 43 in the form of a microphone or a sound transducer. The converting part 32 may be connected to the first connecting means 33, which is in the form of a coupling ring, encircling the opening 37, where the ring 33 is permanently attached to the outer surface 36 of the adhesive part 31.
The free end of the housing 38 is provided with a second connecting means 34 in the form of a first radial protrusion 44 that is capable of snap locking into a second protrusion that is provided as a protrusion 45 or a rim on the free end of the coupling ring 33.
As the converting part is attached to the adhesive part, the skin contacting surface 46 of the converting means 43 is substantially parallel to the skin contacting surface of the adhesive part 31, which means that in converting part comes into contact with the skin surface as the adhesive patch 40 is attached to the skin surface of the user. Any modifications to the size, shape, material choice are obvious to the skilled person based on the teachings of the present invention.
Fig. 4a shows a schematical view of an adhesive part 31 having a compression structure 47 on the skin contacting surface 35 of the adhesive part 31. The compression structure 47 is formed as a tapered surface area 48 of the skin contacting surface 35 which protrudes in a direction away from the adhesive part 31. The tapered surface may be seen as an increase in thickness of the adhesive part 31 where the adhesive part is thinner in the area in a radial direction away from the opening 37 and increases in thickness the closer the area 49 is to the opening 37.
Fig. 4b shows a schematical view of an adhesive part 31 having a compression structure 50 in the form of a circular protrusion 51 on the skin contacting surface 35 of the adhesive part 31.
Fig. 5 shows an adhesive patch 60 according to the present invention applied on the skin surface 61 of a user, having a compression structure 62 as shown in Fig. 4a, where the compression structure 62 encircles the opening 63 and the tapered surface 64 or the protrusion shown in Fig. 4b increases the surface tension and/or stretches the skin surface 65 inside the opening 63 of the user upon application of the adhesive patch 60 and maintain the tension on the skin surface 63 during the continued application of the adhesive patch 60.
In this embodiment, it may be seen that even if the skin surface 66 surrounding the adhesive patch 60 is stretched, deformed or moved in any way, the surface tension of the skin surface 65 inside the opening 63 is maintained, and thus the pressure between the converting means 67 and the skin surface 65 is managed. In this embodiment, a layer of acoustic conducting layer 68 is applied between the skin surface 64 and the converting means 67.
The acoustic conducting layer 68, may in some embodiments stretch throughout the entire opening 63 or just a part of the opening. The layer 68 may be a layer having an adhesive skin contacting surface and have an adhesive layer on the opposite surface.
The layer 68 may be a gel like layer or in some embodiments it may be a layer of a gas, such as air. Any suitable acoustic conducting material known in the art may be used to facilitate acousting transmission or transfer between the skin surface and the converting means.
The embodiments shown in Fig. 4 and 5 are shown as being a part of a two-part device, where the converting part can be releasably connected to the adhesive part. In other embodiments having the same or similar compression structure, the adhesive part may be permanently connected to the converting part, such as shown in the embodiment of Fig. 2.
Any modification made in the shape, form, size and structure of the compression structure shown in Fig. 4 and 5 to obtain similar or the same functionality is obvious to the skilled person based on the present disclosure.
1. An adhesive patch for monitoring acoustic signals from a human or animal body comprising an adhesive part and a converting part, - the adhesive part is provided with an adhesive surface providing a skin contacting surface and a non-adhesive outer surface which faces away from the skin contacting surface, and the adhesive part has a through-going opening which provides communication from the outer surface of the adhesive part to the skin contacting surface, and - the converting part comprises a housing having a cylindrical wall and a back wall where the walls define an inner cavity housing a pressure management element, in the form of resilient foam or similar material, and a converting means for recording the acoustic signals and converting it to a first electric output signal, the adhesive patch further comprises transmitting means for transmitting the output signal to a peripheral device, characterized in that when the converting part is connected to the adhesive part, the skin contacting surface of the converting means, where the converting means being arranged in said opening, is substantially parallel to the skin contacting surface of the adhesive part, resulting in that the converting part comes into contact with the skin surface as the adhesive patch is attached to a skin surface of the user, and that the adhesive part is provided with a compression structure at the skin contacting surface, wherein the compression structure is in the form of one or more protrusions that project out from the skin contacting surface and positioned close to and/or around the converting means and in that the adhesive part and the converting part being releasably connectable to each other via a first connecting means and a second connecting means, and in that the converting means are provided with a skin contacting surface .
2. The adhesive patch according to claim 1, wherein the compression structure is formed as a tampered surface area providing an increase in thickness of the adhesive part where the adhesive part is thinner in the area in a radial direction away from the opening and increases in thickness the closer the area is to the opening.
3. The adhesive patch according to claim 1, wherein the compression structure is in the form of a circular protrusion on the skin contacting surface of the adhesive part.
4. An adhesive patch according to claim 1 or 2, wherein the compression structure is constructed to increase surface tension of the skin of the user.
5. An adhesive patch according to claim 1, wherein the adhesive part comprises an acoustic conducting layer formed of an acoustic conducting material that is provided as a coating that envelopes at least a part of an external surface of the converting means.
6. An adhesive patch according to any of the preceding claims, wherein the converting means includes at least one microphone.
7. An adhesive patch according to claim 6, wherein the at least one microphone is a silicon microphone or a pressure sensitive contact microphone.
8. An adhesive patch according to claim 1, wherein the patch further comprises processing means for processing the first electric output signal and converting it to at least a second electric output signal.
9. An adhesive patch according to claim 1, wherein the adhesive part is a disposable part and the converting part is a reusable part.
CA2709637A 2007-12-20 2008-12-16 An adhesive patch for monitoring acoustic signals Active CA2709637C (en)
CA2709637A1 CA2709637A1 (en) 2009-07-02
CA2709637C true CA2709637C (en) 2016-10-04
CA2709637A Active CA2709637C (en) 2007-12-20 2008-12-16 An adhesive patch for monitoring acoustic signals
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