Abstract:
A device for sensing lung sounds, comprising: a piezoelectric sensor comprising an electrical conductive plate attached to a piezoelectric material, said sensor encased in a body structure; a first electric wire connected to the piezoelectric material on the opposite side of said plate; a second electric wire connected to said plate; a connector connected to the other ends of said first and second electric wires; and an adhesive layer connected to the surface of said plate on the side opposite to the piezoelectric material, said adhesive layer facing away from said plate; said device adapted to provide electrical signals representing vibrations present on the surface of a object when it is attached to said object surface with said adhesive layer; said electrical signals resulting from vibrations on the object surface, wherein stress applied on the piezoelectric material generates electrical voltage-difference on both sides of the piezoelectric material, creating voltage build-up on said first and second electric wires.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    The present application is a national phase application of International Patent Application No. PCT/IB2012/052465 (PCT Publication No. WO2012/156930), filed May 16, 2012, and entitled “BODY SURFACE SENSORS”, which claims priority to U.S. Provisional Patent Application 61/457,719, filed May 18, 2011, and entitled “BODY SURFACE SENSORS”, the disclosures of which are incorporated herein by reference in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention deals with sensors for continuously monitoring vital signs, and more particularly with disposable sensor for continuously monitoring lung sounds, electrical activity of the heart and other vital signs. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are disposable stethoscopes such as Veridian 05-13503 Single Patient Use Disposable Stethoscope (http://www.amazon.com/gp/product/B003UYOUPiezoelectric?tag=theshoclo-20). 
         [0004]    There are electronic stethoscopes such as 3M Littmann Electronic Stethoscope—3100 Mode (http://solutions.3m.com/wps/portal/3M/en_US/Littmann — 3100 — 3200/stethoscope/) 
         [0005]    None of the above is suitable for continuous monitoring of lung sounds. 
         [0006]    There is also no solution for low cost continuous lung sound sensors that can be used for one patient and be disposed after such usage. 
       SUMMARY 
       [0007]    Provide low cost lung sound sensors suitable for continuous monitoring of lung sounds. 
         [0008]    Provide low cost lung sound sensors suitable for continuous monitoring of lung sounds that also support other vital signs monitoring. 
         [0009]    Particularly provide low cost lung sound sensors suitable for continuous monitoring of lung sounds that also support ECG sensing. 
         [0010]    Particularly provide low cost lung sound sensors suitable for continuous monitoring of lung sounds that also support temperature sensing. 
         [0011]    Particularly provide low cost lung sound sensors suitable for continuous monitoring of lung sounds that also function as a sound generator for broadcasting sound waves into the body tissue and recording of the transmitted sounds using same sensors acting as sound sensors. 
         [0012]    Providing combinations of the above functionality in a single sensor while minimizing the area that such a sensor occupies on the patient&#39;s body. 
         [0013]    Providing combinations of the above functionality in a single sensor while minimizing the number of electronic wires required to operate such a senor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Reference is made now to  FIG. 1A  that represents one preferred embodiment of the present invention. 
         [0015]    In this invention, the term “Piezoelectric device” means a layer of piezoelectric material of any kind, in any form of design. In the specific example of the current invention, a Piezoelectric device is represented by the example of an assembly of a layer of piezoelectric ceramics, assembled with a layer of a conductive metal substrate such as Model OBO-TE32211-26 available from OBO Pro.2 Inc., Pa-Te City, Tauyuan, Taiwan. 
         [0016]    It would be appreciated that the invention is not limited to this specific Piezoelectric device. 
         [0017]    Sensor  100  is constructed from a Piezoelectric device. Such a Piezoelectric sensor is constructed from electrical conductive thin disk  101  attached to a Piezoelectric ceramics  102 . When stress is applied on the Piezoelectric device, electrical voltage-difference is generated on both sides of the Piezoelectric ceramics. This results in voltage build-up on wires  106  and  107  that are connected to external connector  108 . This characteristic provides for using such a Piezoelectric device to record vibrations such as present on the body surface as a result from the breathing sounds of a patient. 
         [0018]    The low cost lung sounds sensor  100  is further constructed of a body of material  103  that supports the structure described hereinabove. By selecting suitable material for  103  one can also provides isolation from environment noises to support recording of more pure sound coming from the measured surface. A variety of polyurethane materials can serve such purposes. 
         [0019]    It would be appreciated that body of material  103  is not required for the basic function of device  100  and device  100  can function without it. Body martial  103  is provided here as an improved embodiment of the invention and does not limit the scope of the invention. 
         [0020]    Layer  109  carries an adhesive layer to enable the attachment of device  100  to the surface of a patient. The adhesive would typically be of the types used for ECG stickers such as Medi-Trace 230 ECG Conductive Adhesive Electrodes available from BP Medical Supplies, Brooklyn, N.Y., USA (http://www.bpmedicalsupplies.com/product.sc?productId=657). 
         [0021]    When used for lung sound monitoring, layer  109  can cover the whole bottom surface of device  100 . In this preferred embodiment, layer  109  has an opening  110  that exposes conductive metal  101 , thereby enabling galvanic contact between conductive metal  101  and the skin of the patient. This is provided as an example for a sensor that can also support measuring electrical signals from the body of the patient and it does not limit the scope of the current invention to the configuration of this example. 
         [0022]    Liner  104  is typically made of a polymer and serves to protect adhesive layer  109  from dust or occidental contact. When ready for attachment of device  100  to the skin of the patient, liner  104  is peeled-off as shown by arrow  105 , in the same way that such a liner is used with common ECG adhesive electrodes. 
         [0023]    The device of  FIG. 1A  can be attached to the skin of a person and connected through connector  108  and, preferably, a coax or dual lead shielded cable, to any reading device having suitable analog and digital electronics suitable to record the signal out of this device. Such reading devices are available such as VRIxp from Deep Breeze Ltd., Or Akiva, Israel but are also well established art involving pre-amplifier circuits, analog to digital conversion of the signal and storing in a storage device for further processing by a computer. 
         [0024]      FIG. 1B  provides enhancement to the structure of  FIG. 1A  in the form of volume  111  that can be used as an air gap to separate the Piezoelectric element from relatively hard and heavy body structure  103 . If heavy and hard material is selected for body structure  103  to provide better isolation from environment noise, a direct contact of the Piezoelectric element might drastically affect its&#39; response for the vibrations coming from the patient&#39;s skin. 
         [0025]    Volume  111 , being an air cell or being filled with a relatively soft material can provide the Piezoelectric device with the stress-free environment, allowing for proper sensing of vibrations coming from the patient&#39;s skin. 
         [0026]    Reference is made now to  FIG. 2  which provides a 3D view of device  100  of  FIG. 1 . 
         [0027]      FIG. 2A  is a top view of device  200 . This preferred embodiment is different from the embodiment of  FIG. 1  by element  208  that differs from socket  108  of  FIG. 1  by providing an anchor structure for cable  201  having an on-cable socket  202 . Cable  204  with plug  203  can connect to socket  202  as shown in  FIG. 2B  to transfer the signal produced by device  200  to a suitable electronic device. 
         [0028]      FIG. 2B  presents the device of  FIG. 2A  with the adhesive side  109  visible. 
         [0029]    Opening  110  in the adhesive layer is shown and conductive metal surface  101  of the Piezoelectric device is also shown here. 
         [0030]    Reference is made now to  FIG. 3A .  FIG. 3A  provides an example of how two Piezoelectric devices can be connected to electronic circuit to support both the signals for lung sounds and skin electrical signals such as ECG. 
         [0031]    For clarity, most of the construction elements of device  100  (or  200 ) were removed from this drawing, presenting only the Piezoelectric devices  100 A with its two components: Piezoelectric ceramics layer  102 A and conductive metal layer  101 A and Piezoelectric  100 B with its two components: Piezoelectric ceramics layer  102 B and conductive metal layer  101 B. 
         [0032]      300 A,  300 B and  300 C are 3 differential amplifiers. 
         [0033]    The input side of differential amplifier  300 A is connected the upper surface of Piezoelectric ceramics  102 A and to conductive metal  101 A. When Piezoelectric device  100 A is exposed to vibrations (such as skin vibrations resulting from lung sounds) the voltage difference on the two input wires of differential amplifier  300 A results in Lung Signal  1  useful as an electrical representation of the lung sound signals. 
         [0034]    The input side of differential amplifier  300 C is connected the upper surface of Piezoelectric ceramics  102 B and to conductive metal  101 B. When Piezoelectric device  100 B is exposed to vibrations (such as skin vibrations resulting from lung sounds) the voltage difference on the two input wires of differential amplifier  300 C results in Lung Signal  2  useful as an electrical representation of the lung sound signals. 
         [0035]    The input side of differential amplifier  300 B is connected to the conductive metal  101 A of Piezoelectric device  100 A and to the conductive metal  101 B of Piezoelectric device  100 B. When Piezoelectric devices  100 A and  100 B are exposed to voltage difference on the skin of the patient, the voltage difference on the on the two input wires of differential amplifier  300 B results in ECG Signal  1  useful as an electrical representation of the electrical voltage difference of electrodes  101 A and  101 B. Just as required for ECG. 
         [0036]    It would be appreciated that measurement of skin voltage differences is useful for a variety of applications and ECG is provided as a support of one example only, without limiting the scope of the present invention. 
         [0037]      FIG. 3B  is an example of how the concept of  FIG. 3A  can be expanded to utilize additional sensors using the same method. 
         [0038]    Here Piezoelectric device  100 C is added. 
         [0039]    Also differential amplifiers  300 D,  300 E and  300 F are added. 
         [0040]    With the same method of  FIG. 3A , differential amplifier  300 E provides additional Lung Signal  3 . 
         [0041]    Additional differential amplifier  300 D provides ECG Signal  2  for electrodes  101 A and  101 C. 
         [0042]    Additional differential amplifier  300 F provides ECG Signal  3  for electrodes  101 B and  101 C. 
         [0043]    It will be appreciated that this method can be repeated in the same way to support any number of sensing devices of the current invention, including, but not limited to, 12 leads ECG reading with 12 such sensing devices. 
         [0044]    Reference is made now to  FIG. 4  providing another embodiment of the present invention. 
         [0045]    The configuration of  FIG. 4  is based on the configuration of  FIG. 3A  except that lead  403  of Piezoelectric device  100 A can now be switched between differential amplifier  300 A to provide the sensing function of Lung Signal  1  as described in reference to  FIG. 3A  or switched to signal generator  400  as shown in  FIG. 4 . The switching operation is made through control circuit  401  that represents any switch controlling circuit that can be derived by any electrical signal. 
         [0046]    In this configuration of  FIG. 4 , device  100 A can by attached to the patient skin on one side of the torso and device  100 B can be attached to another side of the torso, as shown by numerical references  901  and  902  of  FIG. 9 . 
         [0047]    In this configuration Piezoelectric device  100 A can be used alternatively to inject vibrations into the patient body (as shown in  FIG. 4 ) or as a regular lung sounds sensor (as it functions when connected to differential amplifier  300 A). 
         [0048]    In this position of switch  402 , signal generator  400  is used to generate sounds. 
         [0049]    Such typical sounds might be a series of different sinusoidal frequencies and given amplitudes. Each of the sinusoidal frequencies is sensed by Piezoelectric device  100 B after traveling through the body tissue. The amplitude of the sinusoidal signals at the position of Piezoelectric device  100 B depends on the content of the tissue separating Piezoelectric device  100 A from Piezoelectric device  100 B and the frequency of the sinusoidal signal. This can be utilized, for example, to estimate amount of water in the lungs of the patient. 
         [0050]      FIG. 4  therefore, demonstrate the 3-function capability of the invention, to provide in one simple and low cost sensor measurements of lung sounds, ECG and tissue content analysis. In more generalized words, the three functions enabled by this embodiment of the invention is sensing skin vibrations, skin galvanic potential differences and injecting vibrations into the body of the patient. 
         [0051]    It would also be appreciated that the configuration of  FIG. 3  and  FIG. 4  can be used with the Piezoelectric device as is, stripped from the various packaging mechanics of the current invention, using only 2-sided tape to attaché the Piezoelectric device to the skin of the patient. Although this is not a referred embodiment of the current invention, the invention is not limited to packaged Piezoelectric devices. 
         [0052]    Reference is made now to  FIG. 5 . This embodiment of the invention is a variation of device  100  of  FIG. 1A . In this embodiment, the Piezoelectric device is positioned in a deeper location in the body material  103  as shown in  FIG. 5A . Open cavity  502  just below conductive metal  101  of the Piezoelectric device provides for placement of conductive gel  503  such as CG04 Saline Base Signa Gel available from Bio-Medical Instruments, Inc., Warren, Mich. USA. 
         [0053]    Usage of such a gel improves the electrical contact for the galvanic signals of the present invention. The gel also provides improved interface to transfer the skin vibration to the Piezoelectric device when irregular skin surface might deteriorate such an interface quality. 
         [0054]    The gel may be included in device  500  covered with liner  104  to protect the device until it is used as shown in  FIG. 8A  and  FIG. 8B . 
         [0055]      FIG. 5B  and  FIG. 5C  provide additional views of device  500  of  FIG. 5 . 
         [0056]    Reference is made now to  FIG. 6  which represents yet another preferred embodiment of the invention where the galvanic skin contact is separated from the Piezoelectric device. 
         [0057]    In  FIG. 6A , a cross section of device  600 , a conductive ring  601  is attached to the skin side of device  600 . Lead  602  connects between conductive ring  601  and snap-button  603  which, in this example, is a standard ECG snap-button suitable for many models of ECG leads such as Welch Allyn ECG Lead Wires for Atlas Monitor available from Welch Allyn Inc., Skaneateles Falls, N.Y., USA. 
         [0058]    Piezoelectric device and its contacts are the same as in  FIG. 1A and 2A . 
         [0059]    This configuration supports the usage of this structure with common ECG devices such as the ECG Atlas Monitor of Welch Allyn and does not require the specifically designed circuits of  FIG. 3A  and  FIG. 3B . This is achieved at the cost of additional lead  605  with the snap-head  604  of  FIG. 6B . 
         [0060]      FIG. 6C  provides a 3D view of the skin side of device  600  of  FIG. 6 . 
         [0061]    Reference is made now to  FIG. 7  which is yet another embodiment that is a variation of the embodiment of  FIG. 6 . 
         [0062]    Unlike device  600  of  FIG. 6  where Piezoelectric device and the galvanic contact device are concentric, in the embodiment of  FIG. 7  the two elements are arranged side-by-side. 
         [0063]      FIG. 7A  provides a cross section of device  700  with the conductive layer  601  positioned to the left of the Piezoelectric device and connected to the ECG snap-button  603  with lead  602  to provide the required galvanic contact to the ECG lead. 
         [0064]    It would be appreciated that the  3  components  601 ,  602  and  603  can be constructed out of one conductive piece that provides both sides of the contacts:  601  and  603 . 
         [0065]      FIG. 7B  provides a view of the skin side of device  700 . On the left side, conductive layer  601  is shown and is available for contact with the skin of the patient. 
         [0066]    Adhesive layer  109  covers the complete area except for the opening required for conductive layer  601  to provide for the necessary skin contact. 
         [0067]    The location of Piezoelectric device conductive metal  101  is shown by a dashed line and is covered by adhesive layer  109 . 
         [0068]      FIG. 7C  provides a  3 D illustration of device  700 , including the illustration of an ECG snap-head  604  and lead  605 . 
         [0069]    Reference is made now to  FIG. 8  which represents yet another preferred embodiment of the current invention. 
         [0070]      FIG. 8  provides a combination of device  700  of  FIG. 7  and conductive gel  503  of  FIG. 5 . 
         [0071]    In this embodiment, conductive layer  503  is mounted in cavity  502 , thus providing for conductive gel  503 . The function of conductive gel  503  in this example is only to enhance galvanic contact and it has no function in reference to the Piezoelectric device as in  FIG. 5 . 
         [0072]    In  FIG. 8A  and  FIG. 8B  liner  104  is also, shown partially peeled off. 
         [0073]      FIG. 9  is an illustration of optional positioning of the devices of the current invention over the body of a patient. 
         [0074]    Locations such as  901  and  902  are particularly useful for measurement of spectral transmission of vibration signals across the tissue that includes the lungs as explained hereinabove. 
         [0075]    Locations such as  903  and  904  are particularly useful in reference to ECG measurements. 
         [0076]    Locations such as  905 ,  906  and  907  are useful both for lung sounds signals and ECG signals. 
         [0077]    It would be appreciated that the locations of the devices of the present invention can vary without limitation per the application for which they are used and that the examples above are provided only as such without limiting the scope of the invention. 
         [0078]    It would also be appreciated that the different combinations design features of the device of the current invention are provided as examples of preferred embodiment and do not limit the scope of the invention. 
         [0079]    The scope of the invention is specified only by the claims.