WO2005053530A1

WO2005053530A1 - Holder for affixing signal pick-up devices to a body surface

Info

Publication number: WO2005053530A1
Application number: PCT/IL2004/001100
Authority: WO
Inventors: Igal Kushnir; Meir Botbol
Original assignee: Deepbreeze Ltd.
Priority date: 2003-12-02
Filing date: 2004-12-02
Publication date: 2005-06-16

Abstract

A holder for affixing two or more signal pick-up devices to a body surface. The signal pick-up devices may be, for example, microphones, electrodes, thermometers, or plethysmographs. The holder comprises a retaining surface formed from an air impervious material. The retaining surface has two or more attachment sites, each attachment site being configured to retain a signal pick-up device. A sealing ring formed from an air impervious material projects from a face of the retaining surface around an edge of the face. A vacuum port is used to connect the holder to a source of negative pressure for evacuating a chamber defined by the holder and the body surface when the sealing ring is applied to the body surface. The holder may be used in a system for recording and analyzing body signals.

Description

HOLDER FOR AFFIXING SIGNAL PICK-UP DEVICES TO A BODY SURFACE

FIELD OF THE INVENTION This invention relates to medical devices and more particularly to such devices for affixing signal pick-up devices such as a microphone or electrode, to a body surface.

BACKGROUND OF THE INVENTION Body sounds are routinely used by physicians in the diagnosis of various disorders. A physician may place a stethoscope on a person's chest or back and monitor the person's breathing or heart sounds in order to detect adventitious (i.e. abnormal or unexpected) body sounds. The identification and classification of these adventitious sounds often provide important information about pulmonary abnormalities. It is also known to fix a microphone to the body in order to record body sounds. The recorded sound signals may be amplified and filtered before being listened to by the physician. The recorded signals may also be analyzed by signal processing techniques. U.S. Patent 5,957,866 to Shapiro et al. discloses analysis of sound signals obtained by a microphone applied to a body surface. It is also known to affix a plurality of microphones over a body surface in order to obtain a plurality of sound signals simultaneously from the body surface. Applicant's U.S. Patent Application, Serial No. 10/338,742 filed on January 9, 2003 discloses a system in which a plurality of microphones are affixed to a person's back or chest for recording respiratory tract sounds. This patent application teaches embedding the signal pick-up devices in a matrix that may be in the form of a vest or garment securely worn by the person during signal acquisition. Different sized or shaped matrixes may be used for differently sized individuals, for different sexes, ages, etc. U.S. Patent No. 6,394,967 discloses a system in which a plurality of microphones are affixed to a person's back or chest for recording respiratory tract 5 sound. This patent teaches affixing the signal pick-up devices to the body surface using tape or straps to prevent dislocation or movement during the data acquisition process. Kompis et al. (Chest 120:4, 2001, 1309-1321) discloses affixing eight or sixteen microphones to an individual's chest for obtaining respiratory tract signals, l o but the method of attachment is not disclosed. U.S. Patent No. 4,777,961 discloses affixing a microphone to a body surface by means of suction. A microphone embedded in the wall of a dome shaped stethoscope head is formed from an elastic flexible material. The stethoscope head is squeezed by fingertip pressure as it is applied to the body surface. When the 15 fingertip pressure is removed, the head expands slightly so as to create a partial vacuum in its interior so as to keep the head affixed to the body surface. The membrane of the microphone, however, is not pressed against the body surface. U.S. Patent No. 4,736,749 discloses a holder for a signal pick-up device, such as a microphone or electrode that is fixed to the body surface by vacuum. The 20 holder has a chamber that is evacuated by an external source of negative pressure. When the chamber is evacuated, the holder is held firmly to the skin and the signal- pick up device is pressed to the skin inside the chamber.

SUMMARY OF THE INVENTION

25 In its first aspect, the present invention provides an holder for affixing two or more signal pick-up devices to a body surface by means of a vacuum. The signal pick-up device may be, for example, a microphone, electrode, thermometer, or plethysmograph. The holder is formed from a flexible material that is air impervious such as silicon. The holder consists of a flexible retaining surface. Around the edge of the retaining surface on one face is a sealing ring, also formed from a flexible air impervious material. In the retaining surface are two or more attachment sites. Each attachment site is configured to receive a signal pick-up device. The holder is further provided with a vacuum port for attachment of a source of negative pressure. With the signal pick-up devices inserted into the retaining surface, the holder is placed on a body surface with the sealing ring of the holder in contact with the body surface. A small volume of air is thus enclosed in the space bounded by the retaining surface, the sealing ring and the body surface. When this space is partially evacuated, the signal pick-up devices are pressed upon the body surface. As explained in detail below, including two or more signal pick-up devices in a single holder provides a desired force of attachment of the signal pick-up devices to the body surface with a smaller negative pressure than is required when each signal pick-up device is in a separate holder. In its second aspect, the invention provides a matrix for affixing a plurality of signal pick-up devices to a body surface. The matrix comprises one or more holders of the invention. The matrix further comprises a harness containing a vacuum tube for connecting each holder to a source of negative pressure. The vacuum tube has one or more extensions, where each extension is configured to be connected to the vacuum port of a holder. The matrix may further comprise electrical wires for connecting each signal pick-up device to electrical circuitry for recording and/or analyzing signals detected by the signal pick-up devices. In its third aspect, the invention provides a system for obtaining signals from a body surface. The system comprises one or more matrices of the invention. The system further comprises one or more vacuum pumps for creating and maintaining a partial vacuum in the holders. The system further comprises electrical circuitry for recording and/or processing signals obtained by the signal pick-up devices. The system may optionally comprise a display for displaying the signals or the results of processing the signals. Electronic circuitry for processing acoustic signals obtained from two or more microphones, are disclosed in U.S. Patent No. 6,394,967 to Murphy, Kompis et al. (Chest 120:4, 2001, 1309-1321) and in Applicant's pending U.S. Patent Application Serial No. 10/338,742 filed on January 9, 2003.

BRIEF DESCRIPTION OF THE DRAWINGS In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 shows a holder for affixing two or more signal pick-up devices to a body surface in accordance with one embodiment of the invention; Fig. 2 shows a microphone in exploded view for use with the holder of Fig.l; Fig. 3 shows the holder of Fig. 1 with the microphones of Fig. 2; Fig. 4 shows a matrix for affixing signal pick-up devices to a body surface in accordance with an embodiment of the invention; and Fig. 5 shows a holder for affixing two or more signal pick-up devices to a body surface in accordance with another embodiment of the invention; Fig. 6 shows a microphone in exploded view for use with the holder of Fig.l; Fig. 7 shows the holder of Fig. 5 with the microphones of Fig. 6; Fig. 8 shows a matrix for affixing signal pick-up devices to a body surface in accordance with another embodiment of the invention; and Fig. 9 shows a system for recording and analyzing body signals in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment of the invention are described below in which the signal pick- up devices are microphones for recording body sounds such as respiratory tract sounds or heart sounds. This is by example only, it being obvious to those skilled in the art, that the invention may be practiced with any signal pick-up device. Fig. 1 shows a holder 10 in accordance with one embodiment of the invention. The holder 10 is shown in a perspective view from above in Fig. la and is shown in a perspective view from below in Fig. lb. The holder 10 comprises a retaining surface 12. The retaining surface 12 has an upper face 14 and a lower face 16. The terms "upper face" and "lower face" are used here for clarity in the description, and are not intended to imply that the holder 10 has any particular orientation in space when in use. Around the edge of the bottom face 16 extends a sealing ring 18. Two or more openings 20 are formed in the retaining surface 12. In the holder 10, three openings 20 are shown. This is by way of example only, and the holder 10 may be any number of openings greater than or equal to two, in accordance with the invention. Each opening 20 serves as an attachment site for a signal pick-up device such as a microphone, as described below. The upper face 14 of the holder 10 is provided with a vacuum port 22 for linkage to a source of negative pressure, as described in detail below. A conduit 24 passes through the vacuum port 22 from the upper face 14 through the retaining surface 12 to the lower face 16. Fig. 2 shows a microphone 11 in exploded view that can be used with the holder 10. The microphone 11 consists of a core sensor 26 that fits into a housing 28. A pre-amplifier 30 amplifies electrical signals indicative of acoustic signals detected by the core sensor 26. A brass ring 32 has a mass that is selected to dampen vibrations above a predetermined frequency. For example, in the case that lung sounds are to be detected, the brass ring 32 will have a mass so as to dampen vibrations over 400 Hz. A casing 34 surrounds the housing 28 and has a cover 36. The microphone is assembled and held together by screwing the cover 36 onto the housing 28 by means of screw threads 38 on the cover and mated screw threads 40 on the housing 28. Two O-rings 42 serve to immobilize the preamplifier 30 between the cover 36 and the housing 34. Fig. 3a shows three microphones 11 after assembly into the holder 10. The holder 10 has been placed on a body surface 42, such as a person's chest or back. An enclosed chamber 46 is formed by the body surface 42 and the holder 10. The retaining surface 12 of the holder 10 is lodged between a lip 44 of the housing (Fig.2) and the preamplifier 30, so as to form an air tight seal between the microphones 11 and the retaining surface 12 of the holder 10. As explained below, the chamber 46 is evacuated by connecting a vacuum hose 48 at one end to the vacuum port 22, and at its other end to a source of negative pressure. Fig. 3b shows the holder with the microphones after evacuation of the chamber. As can be seen, the core sensor 26 of each microphone 11 is pressed against the body surface 42. The area A (cm ) of contact between the retaining surface 12 and the body surface 42 when the holder 10 is evacuated, the vacuum V (gram/cm²) in the evacuated chamber 46, and the force F (in grams) on each microphone when the chamber is evacuated are related by F = V A. When two or more microphones 11 are included within a single holder, area between the microphones contributes to A. As can be seen in Fig. 3b, almost the entire surface area of the retaining surface 12 overlies the body surface 42. In contrast to this, when each microphone is included in a separate holder, some of the area between the microphones will be outside all of the chambers, leading to a smaller A. Thus, the relatively large area A contact between the retaining surface 12 and the body surface 42 (in comparison to a system wherein each microphone is in a separate holder), allows a lower value V in order to attain a specific force F. With the holder 10, a vacuum of less than 120 mbar is sufficient to achieve a force of about 350 grams on each microphone. A reduced V decreases the chances of haemotoma. The sealing ring 18 is constructed so as to prevent collapse of the retaining surface 12 onto the body surface 42. The retaining surface 12 should be formed from a material that is sufficiently stiff so as to minimize its sagging into the chamber 46 when the chamber 46 is evacuated. Sagging of the retaining surface 12 is further reduced by several projections 49 that extend from the lower surface 16 of the retaining surface 12 and contact the body surface 46. The sealing ring 18 should preferably sufficiently high so as to prevent contact of the retaining surface 12 with the body surface 42 when the chamber 46 is evacuated. Because the core sensor 26 is surrounded by vacuum (apart from the microphone membrane which is in contact with the body surface), the core sensor 26 is acoustically isolated from sound vibrations not arising from the body. This improves the signal to noise ratio of the detected sound signals. The microphones 11 are preferably uni-directional microphones that detect only vibrations in the body surface 42. The sealing ring 18 should be formed from a soft and elastic material such as sponge rubber in order to provide a robust, flexible and forgiving seal that maintains the seal despite skin movement or skin imperfections such as hairs, pimples, pock marks, etc. The retaining surface 12 and the sealing ring 18 may be made from the same material. Preferably, however, the sealing ring 18 is made from a material having a shore that is smaller than the shore of the retaining surface 12. For example, the sealing ring 18 may have a shore of 15 while the retaining surface has a shore of 50 -60. The smaller shore of the sealing ring 18 allows the sealing ring to be compressed, as shown in Fig. 3 b, so as to increase the area of contact between the retaining surface 12 and the body surface 42. Fig. 4 shows a matrix 50 in accordance with the invention. The matrix 50 includes one or more holders 10 in accordance with the invention. The matrix 50 shown in Fig. 4 has seven holders 10. This is by way of example only, and any number of holders may be used, where each holder is associated with any number of microphones greater than 1. The matrix includes a harness 52 containing a vacuum hose 54 for supplying a negative pressure to each holder. The vacuum hose 54 extends from a free end 56 of the harness, and terminates in one or more extensions 58, there being a separate extension 58 for each holder 10, where each extension 58 is connected to the vacuum port 22 of a different holder 10. The harness 54 also includes a cable 59 of wires 60. The wires in the cable 60 provide each microphone 11 with a voltage for activating the preamplifier in the microphone, and also serve for transmitting a voltage signal to recording or analyzing circuitry when wires connected to a microphone are connected at another end to recording or analyzing circuitry, as described below. The cable terminates in a plug 62 for attachment to recording or analyzing circuitry. In a preferred embodiment, the wires are in the form of a printed circuit, most preferably a flexible printed circuit. In another preferred embodiment, the signal pick-up devices, such as the microphones 11 are wireless. In this case, the harness 52 may not contain any wires. It should be noted that one or more signal pick-up devices in the matrix may be replaced with a dummy if it is not desired to obtain a signal from that location on the body surface. Fig. 5 shows a holder 63 in accordance with another embodiment of the invention. The holder 63 is shown in a perspective view from above in Fig. 5a and is shown in a perspective view from below in Fig. 5b. The holder 63 has components in common with the holder 10, and similar components are indicated in both figures with the same reference numeral. In particular, the holder 63 has a sealing ring 18 and two or more openings 20 formed in the retaining surface 12 that serve as an attachment site for a signal pick-up device such as a microphone, as described below. The upper face 14 of the holder 63 is provided with two vacuum ports 62 for linkage to a source of negative pressure, as described in detail below. Each opening 20 is surrounded on the upper face 14 by a cylindrical extension 15. A conduit 64 passes through the vacuum port 22 from the upper face 14 through the retaining surface 12 to the lower face 16. Fig. 6 shows a microphone 61 in exploded view that can be used with the holder 63. The microphone 61 consists of a core sensor 76 that fits into a housing 78. A pre-amplifier 80 amplifies electrical signals indicative of acoustic signals detected by the core sensor 76. Brass spacers 82 have a mass that is selected to dampen vibrations above a predetermined frequency. For example, in the case that lung sounds are to be detected, the brass spacers 82 are selected so as to dampen vibrations over 400 Hz. The microphone is assembled and held together by means of mated male and female screws 86 extending that secure the housing 78 to a base plate 79. The base plate 79 has a cylindrical extension 81 that terminates in a disc 83. Two spring washers 91 serve to immobilize the preamplifier 80 inside the housing 78. between the base plate 79 and the core sensor 76 is a disk 87 that serves as an acoustic coupler. The disk 87 may be made from silicon. Fig. 7a shows three microphones 61 after assembly into the holder 63. The holder 63 has been placed on a body surface 92, such as a person's chest or back. An enclosed chamber 96 is formed by the body surface 42 and the holder 63. Each cylindrical extension 15 of the holder 60 is lodged between the base plate 79 and the disc 83, so as to form an air tight seal between the microphones 61 and the retaining surface 12 of the holder 63. As explained below, the chamber 96 is evacuated by connecting a vacuum hose 98 at one end to the vacuum ports 62, and at its other end to a source of negative pressure. Fig. 7b shows the holder 63 with the microphones 61 after evacuation of the chamber 96. The disk 83 of each microphone 61 is pressed against the body surface 92. The area A (cm ) of contact between the retaining surface 12 and the body surface 92 when the holder 63 is evacuated, the vacuum V (gram/cm²) in the evacuated chamber 96, and the force F (in grams) on each microphone when the chamber is evacuated are related by F = V'A. When two or more microphones 61 are included within a single holder, area between the microphones contributes to A. As can be seen in Fig. 7b, almost the entire surface area of the retaining surface 12 overlies the body surface 92. In contrast to this, when each microphone is included in a separate holder, some of the area between the microphones will be outside all of the chambers, leading to a smaller A. Thus, the relatively large area A contact between the retaining surface 12 and the body surface 92 (in comparison to a system wherein each microphone is in a separate holder), allows a lower value V in order to attain a specific force F. With the holder 60, a vacuum of less than 120 mbar is sufficient to achieve a force of about 350 grams on each microphone. A reduced V decreases the chances of haemotoma. The core sensor 76 is bonded to the coupler 87 which is pressed to the base plate 79 in the assembled microphone. This improves the signal to noise ratio of the detected sound signals. The microphones 61 are preferably uni-directional microphones that detect only vibrations in the body surface 92. Fig. 8 shows a matrix 100 in accordance with the invention. The matrix 100 includes one or more holders 63 in accordance with the invention. The matrix 100 5 shown in Fig. 8 has seven holders 63. This is by way of example only, and any number of holders may be used, where each holder is associated with any number of microphones greater than 1. The matrix includes a distribution system 102 containing two vacuum hoses 104 for supplying a negative pressure to each holder 63. The vacuum hoses 104 extend from a socket 106 of the harness and supplies a

10 negative pressure to each of the vacuum ports 62 when the socket 106 is connected to a source of negative pressure. The distribution system also includes two cables 109 of wires 110. The wires in the cable 109 provide each microphone 61 with a voltage for activating the preamplifier in the microphone, and also serve for transmitting a voltage signal to recording or analyzing circuitry when wires

15 connected to a microphone are connected at another end to recording or analyzing circuitry, as described below. The cables 109 terminate at the socket 106 for attachment to recording or analyzing circuitry. In a preferred embodiment, the wires are in the form of a printed circuit, most preferably a flexible printed circuit. In another preferred embodiment, the signal pick-up devices, such as the microphones

20 61 are wireless. In this case, the harness 102 may not contain any wires. Fig. 9 shows a system for recording and/or analyzing two or more sound signals, in accordance with the invention. The system includes two matrices 50a and 50b, or alternatively the two matrices 100 (not shown) of the invention. The vacuum hose 54 is connected to a source of negative pressure 62. The source of

25 negative pressure 62 comprises a vacuum pump 64 and an accumulator 66. The vacuum pump 64 is used to attain the desired vacuum in the chamber 46 of the holders 10. A valve 133 may inserted between the matrices 50 that is initially closed so that a vacuum is applied only to the matrix 50a. After the desired vacuum has been achieved under the matrix 50a, the valve 133 is opened so as to allow a

30 vacuum to form under the matrix 50b. After the desired vacuum has been attained under both matrices 50 and 50b, a valve 131 is closed, and the accumulator 66 is used to maintain the desired vacuum in the holders. In Fig. 9 the matrices 50a and 50b are shown after being affixed by vacuum to the body surface of an individual 110. Each signal pick-up device 11 produces an analog voltage signal indicative of pressure waves arriving to that signal pick-up device. The analog voltage signals are conducted via the pairs of wires 60 in the cable 59 to electronic circuitry for recording and/or analyzing voltage signals from the signal pick-up devices. Fig. 9 shows exemplary electronic circuitry that may be used in the system of the invention. This is by way of example only, and any method for analyzing body sounds may be used in the system of the invention. In the circuitry shown in Fig. 9, the analog signals are digitized by a multi-channel analog to digital converter 120. The digital data signals 125, are input to a memory 130. Data input to the memory 130 are accessed by a processor 135 configured to process the data signals 125. The signals 125 may be denoised by filtering components having frequencies outside of the range of body sounds in the body region, for example, vibrations due to movement of the individual. Each signal 125 may also be subject to band pass filtering so that only frequency components in the signal within a range of interest are analyzed. An input device such as a computer keyboard 140 or mouse 145 is used to input relevant information relating to the examination such as personal details of the individual 110. A display screen 150 is used to display the signals 125 or the results of the processing.

Claims

CLAIMS:

1. A holder for affixing two or more signal pick-up devices to a body surface comprising:

(a) a retaining surface formed from an air impervious material, the retaining surface having two or more attachment sites, each attachment site being configured to retain a signal pick-up device;

(b) a sealing ring formed from an air impervious material projecting from a face of the retaining surface around an edge of the face; and

(c) a vacuum port for linkage to a source of negative pressure for evacuating a chamber defined by the holder and the body surface when the sealing ring is applied to the body surface and signal pick-up devices are retained in the attachment sites.

2. The holder according to Claim 1 wherein the retaining surface has three or more attachment sites.

3. The holder according to Claim 1 wherein the sealing ring has a shore that is less than the shore of the retaining surface.

4. The holder according to Claim 3 wherein the shore of the sealing ring is less than 20.

5. The holder according to Claim 1 further comprising a signal pick-up device retained at each of two or more attachment sites.

6. The holder according to Claim 5 wherein one or more signal pick-up devices is wireless.

7. The holder according to Claim 5 or 6 wherein one or more of the pick-up devices is a microphone, electrode, thermometer, or plethysmograph.

8. A matrix comprising:

(a) one or more holders according to Claim 1 ; and

(b) a harness comprising a vacuum hose having one or more extensions, each extension connected to the vacuum port of a holder;

9. The matrix according to Claim 8 wherein the harness further comprises wires or a printed circuit for connection to one or more signal pick-up devices.

10. The matrix according to Claim 8 further comprising a signal pick-up device at each of two or more attachment sites.

11. The matrix according to Claim 10 wherein at least one of the signal pickup devices is wireless.

12. The matrix according to Claim 10 wherein one or more signal pick-up devices are connected to wires or a printed circuit in the harness.

13. The matrix according to any one of Claims 10 to 12 wherein at least one of the signal pick-up devices is a microphone, electrode, thermometer, or plethysmograph.

14. A system for analyzing body signals comprising:

(a) one or more matrices according to Claim 8;

(b) a source of negative pressure; and (c) electronic circuitry for analyzing electronic signals obtained by the signal pick-up devices.

15. The system according to Claim 14 wherein the body signals are sound signals.

16. The system according to Claim 14 wherein the source of negative pressure comprises one or more vacuum pumps.

17. The system according to Claim 16 wherein the source of negative pressure comprises a first vacuum pump for attaining a predetermined vacuum in a holder and a second vacuum pump for maintaining a vacuum in a holder attained by the first pump.

18. The system according to any one of Claims 14 to 17 further comprising a vacuum accumulator.