Devices for determining the relative spatial change in subsurface resistivities across frequencies in tissue

• US 8,700,121 B2
• Filed: 12/14/2012
• Issued: 04/15/2014
• Est. Priority Date: 12/14/2011
• Status: Expired due to Fees

• Current Assignee: ImpediMed Limited
• Original Assignee: Intersection Medical, Inc.
• Inventors: Erlinger, Paul J., Chetham, Scott M., De Limon, Alfonso L., Srivastava, Eniko
• Primary Examiner(s): Cohen, Lee S
• Assistant Examiner(s): Cardinal, Erin M
• Application Number:
  US13/715,722
• Publication Number:
  US 20130165760A1
• Time in Patent Office: 487 Days
• Field of Search: 600/372, 600391-393, 600/396, 600/547, 600/506, 600/507
• US Class Current: 600/391
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 2562/164 the sensor is mounted in or on a conformable substrate or carrier
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/68335 including release sheets or liners
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7271 Specific aspects of physiological measurement analysis A61B5/316, A61B5/349 and A61B5/374 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

Sensors for non-invasively determining tissue wetness/hydration based on relative changes in subsurface resistivities in tissue below the sensor when applied to a human body across different frequencies. A sensor including arrays of current-injecting and voltage-sensing electrodes may be placed on a subject'"'"'s back to determine lung wetness. Sensors may be used as part of a systems and method for determining tissue water content, systems and methods for determining lung wetness, or the like. Sensors for determining relative changes in subsurface resistivities across frequencies and systems include arrays of electrodes used to determine relative changes in subsurface resistivities across frequencies may include pairs of current-injecting and voltage sensing electrodes.

Claims

1. A non-invasive lung wetness sensor, the sensor comprising:

a support backing extending along a proximal to distal axis;

a plurality of elongate electrodes each the same size and having a length of between about 1.5 and about 2.5 inches and a width of between about 0.1 and about 0.5 inches, wherein the electrodes are arranged with their lengths perpendicular to the proximal to distal axis on a subject-contacting surface of the support backing so that the electrodes extend in a line parallel to the proximal to distal axis of the support backing to form an active region that extends between about 6 and about 14 inches along the proximal to distal axis; and

wherein the plurality of electrodes in the active region are configured to form a plurality of pairs of current-injecting electrodes and a plurality of pairs of voltage detection electrodes.

2. The sensor of claim 1, wherein the support backing is flexible and relatively inelastic, so that the spacing between each of the electrodes remains relatively fixed as the sensor is manipulated.

3. The sensor of claim 1, further comprising an adhesive hydrogel on the subject-contacting surface that is configured to secure the sensor to a subject'"'"'s back.

4. The sensor of claim 1, wherein the support backing is less than about 5 mils thick.

5. The sensor of claim 1, wherein a width of the support backing is less than 2.5 inches.

6. The sensor of claim 1, wherein the support backing comprises a polyester material and an anti-bacterial titanium oxide material.

7. The sensor of claim 1, wherein the plurality of electrodes comprise more than 6 electrodes.

8. The sensor of claim 1, wherein the electrodes have a rectangular shape on the support backing.

9. The sensor of claim 1, further comprising a plurality of leads extending only from one side of the support backing.

10. The sensor of claim 1, wherein the active region extends substantially across an entire width of the support backing.

11. The sensor of claim 1, wherein the electrodes comprise silver/silver chloride electrodes.

12. The sensor of claim 1, wherein the sensor has a thickness of less than about 5 mils.

13. The sensor of claim 1, wherein the electrodes are separated by a fixed distance of between about 0.2 and about 0.5 inches on center down the proximal to distal axis in the active region.

14. The sensor of claim 1, wherein the current-injecting electrodes and voltage detection electrodes alternate along the proximal to distal axis in of the active region.

15. The sensor of claim 1, wherein any electrode can be both a current-injecting electrode and a voltage detection electrode.

16. A non-invasive lung wetness sensor, the sensor comprising:

a support backing extending in a proximal to distal axis, wherein the support backing is flexible and inelastic;

a plurality of six or more elongate electrodes, each the same size and having a length of between about 1.5 and about 2.5 inches and a width of between about 0.1 and about 0.5 inches, wherein the electrodes are arranged with their lengths perpendicular to the proximal to distal axis on a subject-contacting surface of the support backing so that the electrodes extend in a line parallel to the proximal to distal axis of the support backing to form an active region that extends between about 6 and about 14 inches along the proximal to distal axis; and

an adhesive, conductive hydrogel on the subject-contacting surface that is configured to secure the sensor to a subject'"'"'s back.

17. The sensor of claim 16, wherein the hydrogel extends completely over the subject-contacting surface of the backing.

18. The sensor of claim 16, wherein the sensor does not include an additional adhesive gasket.

19. The sensor of claim 16, further comprising a plurality of leads, wherein each electrode is connected with a lead from the plurality of leads, wherein each lead extends from a first side of the support backing.

20. The sensor of claim 16, wherein the support backing is sufficiently flexible and inelastic so that the spacing between each of the electrodes remains relatively fixed as the sensor is placed under tension or compression of less than about two pounds of force.

21. The sensor of claim 16, wherein the support backing is less than about 5 mils thick.

22. The sensor of claim 16, wherein a width of the support backing is less than 2.5 inches.

23. The sensor of claim 16, wherein the support backing comprises an anti-bacterial titanium oxide material.

24. The sensor of claim 16, wherein the electrodes have a rectangular shape on the support backing.

25. The sensor of claim 16, wherein the active region extends substantially across an entire width of the support backing.

26. The sensor of claim 16, wherein the electrodes comprise silver/silver chloride electrodes.

27. The sensor of claim 16, wherein the sensor has a thickness of less than about 5 mils.

28. The sensor of claim 16, wherein the electrodes are separated by a fixed distance of between about 0.2 and about 0.5 inches on center down the proximal to distal axis in the active region.

29. The sensor of claim 16, wherein the electrodes comprise current-injecting electrodes and voltage detection electrodes that alternate along the proximal to distal axis in the active region.

30. A non-invasive lung wetness sensor, the sensor comprising:

a flexible and inelastic support backing of less than about 5 mils thickness extending in a proximal to distal axis;

a plurality of six or more elongate electrodes, each the same size and having a length of between about 1.5 and about 2.5 inches and a width of between about 0.1 and about 0.5 inches, wherein the electrodes are arranged with their lengths perpendicular to the proximal to distal axis on a subject-contacting surface of the support backing so that the electrodes extend in a line parallel to the proximal to distal axis of the support backing to form an active region that extends between about 6 and about 14 inches along the proximal to distal axis;

an adhesive, conductive hydrogel extending completely over the active region on the subject-contacting surface that is configured to secure the sensor to a subject'"'"'s back;

an anti-bacterial titanium oxide coating over at least a portion of the support backing; and

a plurality of leads, wherein each electrode is connected with a lead from the plurality of leads, wherein each lead extends from a first side of the support backing.