SENSOR SYSTEM

• US 20100256512A1
• Filed: 06/10/2008
• Published: 10/07/2010
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: Sonomedical Pty., Ltd.
• Original Assignee: Sonomedical Pty., Ltd.
• Inventors: Sullivan, Colin Edward
• Granted Patent: US 8,979,766 B2
• Time in Patent Office: Days
• US Class Current: 600/529
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: A61G 2203/36 for motion
• CPC Class Codes: G01H 11/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
• CPC Class Codes: G01H 11/08 using piezoelectric devices

Abstract

A sensor system comprises a mat (20) for placement over a patient'"'"'s mattress including a number of sensors (10) located in the mat. The sensors include a sensor housing (12), a sound vibration sensing element in the form of a PVDF membrane (13), and means for amplifying sensed sounds. The PVDF membrane is coated/covered with a typically latex, impedance matching layer (14). The sensor automatically provides for auscultation, in which the patient'"'"'s own weight, from the patient lying on the bed, compresses their thorax against the membrane, compressing also the patient'"'"'s clothing, bed sheet and mattress cover material between the two. The recoil in the mattress opposes the body mass, thus compressing the membrane against the thorax. The impedance matching layer on top of the membrane transmits fine breath sounds through to the membrane as the latex does not weaken or attenuate the fine breath sounds but transmits them to the PVDF membrane. However being flexible, it is not uncomfortable to lie on.

Claims

1. A sensor system comprising:

a mat for placement over a patient'"'"'s mattress;

at least one sensor and preferably a plurality of sensors, located in the mat;

the sensor or sensors including a sensor housing, a sound vibration sensing element in the form of a membrane, and means for amplifying sensed sounds; and

wherein the membrane is coated/covered with a flexible and/or deformable, and preferably impedance matching, layer which transfers relatively high frequency breath sounds to the membrane without significant attenuating those high frequency breath sounds.

2. A sensor system as claimed in claim 1 wherein the membrane is a PVDF membrane.

3. A sensor system as claimed in claim 1 wherein the impedance matching layer is latex.

4. A sensor system as claimed in claim 1 wherein the mat comprises foam rubber.

5. A sensor system as claimed in claim 4 wherein the foam rubber comprises a layer which is about 5 cm thick.

6. A sensor system as claimed in claim 4 wherein the sensors are mounted in holes formed in the foam rubber.

7. A sensor system as claimed in claim 4 wherein biasing means are provided to bias the membrane and latex layer upwards in use against a patient lying on the foam rubber.

8. A sensor system as claimed in claim 1 wherein the sensor housing is a thin flat cylinder and is mounted in an elastomeric envelope/container for mounting the sensor in the mat, and which acts as an independent suspension means that compresses the sensor against the overlying subject.

9. A sensor system as claimed in claim 8 wherein the envelope defines a continuous upper surface, defining a central portion beneath which a recess is defined having depending side walls and an internal flange for mounting the sensor housing therein and wherein an external flange is provided for mounting the envelope over an aperture in the mat and a relatively thinner portion connects the flange to the central portion of the envelope.

10. A sensor system as claimed in claim 9 wherein the central portion of the envelope protrudes relative to the external flange and acts as a biasing means to bias the sensor into contact with the patient, in use.

11. A sensor system as claimed in claim 1 wherein the mat is rectangular and is sized to fit on top of a typical mattress.

12. A sensor system as claimed claim 11 wherein the sensor system includes four sensors arranged in the second quarter of the mattress measured from the top edge/head an arranged in a diamond formation such that, in use, at least one sensor is typically positioned against a patient'"'"'s thorax to record breath sounds.

13. A sensor for use in the system of claim 1 comprising a sensor housing, a sound vibration sensing element in the form of a membrane, and means for amplifying sensed sounds, and wherein the membrane is coated/covered with an impedance matching layer.

14. A sensor as claimed in claim 13 wherein the impedance matching layer comprises latex.

15. A sensor as claimed in claim 13 wherein the membrane/housing diameter is from 30 to 50 mm.

16. A sensor as claimed in claim 15 wherein the membrane/housing diameter is about 40 mm.

17. A sensor as claimed in claim 1 wherein the sensor simultaneously detects low frequency period movement/vibrations of breathing efforts as well as the relatively higher frequency breath sounds.

18. A sensor as claimed in claim 17 wherein the relatively higher frequency breath sounds are in the range of 100 to 2000 Hz.

19. A method of monitoring a patient'"'"'s breathing comprising recording and listening to or analysing the low and high frequency breath movements, vibrations and sounds generated by the patient using the sensor system as claimed in claim 1.

20. A method of detecting sleep apnea in a patient lying on top of the sensor system as claimed in claim 1 comprising the steps of recording and listening to or analyzing the low and high frequency breathing sounds generated by the patient and in particular listening to or analyzing breathing characteristic of obstructive apnea by using the high frequency breath sounds to detect when breathing efforts are made without resultant air flow.

21. A method of detecting asthma in a patient lying on top of the sensor system as claimed in claim 1 comprising the steps of recording and listening to or analyzing the low and high frequency breathing sounds generated by the patient and in particular listening to or analyzing the high frequency sounds to detect wheezing.

22. A method of detecting the presence or onset of heart failure in a patient lying on top of the sensor system as claimed in claim 1 comprising the steps of recording and listening to or analyzing the low and high frequency breathing sounds generated by the patient and in particular listening to or analyzing the high frequency sounds to detect crepitations.

23. A method of detecting and separately indentifying central, obstructive and mixed apneas by use of a sensor/mat system that can simultaneously detect the periodic movements of breathing efforts and the vibrations generated by air flow in an out of the lungs of a subject lying on a bed.

24. A sensor system that can simultaneously detect the periodic movements that are generated by breathing and the vibrations that area generated by the normal flow of air into and out of the lungs during normal breathing.