Method and apparatus for enhancing the integrity of an implantable sensor device

• US 7,162,289 B2
• Filed: 12/31/2002
• Issued: 01/09/2007
• Est. Priority Date: 09/27/2002
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Shah, Rajiv, Miller, Michael, Gottlieb, Rebecca, Reghabi, Bahar, Zhang, Yanan
• Primary Examiner(s): Marmor, II; Charles A
• Assistant Examiner(s): MALLARI, PATRICIA C
• Application Number:
  US10/335,574
• Publication Number:
  US 20040064156A1
• Time in Patent Office: 1,470 Days
• Field of Search: 20440301-40306, 20440311-40314, 204/400, 204/403.1, 600/486, 600/488, 600/561, 600/300, 600/316, 600322-325, 600/372, 600/373, 600/459, 600/462, 600/466, 600/467
• US Class Current: 600/345
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A method and apparatus for enhancing the integrity of an implantable sensor. Voids formed between an outer tubing and a sensor substrate or spacing element may be back-filled with a curable, implantable material, minimizing the extent to which unwanted fluids diffuse within the sensor. An enzyme or protein matrix pellet below the sensor window may be pre-treated with a reducing agent to enhance its bond stability, and to reduce undesired swelling that may cause the sensor window to detach or leak. The bonding between the enzyme pellet and a hydrogel layer may be reinforced by application of an intervening bonding layer of a protein material, such as human serum albumin (HSA). The size of the window may be minimized by minimizing the size of an underlying electrode, providing reduced flux and lengthening sensor. A coating may be deposited on the surface of the sensor leads, providing stiffening and lubrication.

Claims

1. An implantable sensing apparatus comprising:

a substrate having an electrode;

an outer tubing surrounding said substrate, said outer tubing having a window opening; and

an enzyme aligned between said electrode and said window opening, said enzyme treated with a reducing agent to inhibit excessive swelling.

2. The apparatus of claim 1, wherein said reducing agent comprises Ascorbate.

3. The apparatus of claim 1, wherein said reducing agent comprises cyanoborohydride.

4. The apparatus of claim 1, wherein the outer tubing is coated with a lubricious coating.

5. The apparatus of claim 4, wherein the lubricious coating is siloxane.

6. The apparatus of claim 1, further comprising an inner tubing disposed within an interior of the outer tubing.

7. The apparatus of claim 6, wherein the inner tubing is made from an elastomeric material.

8. The apparatus of claim 6, wherein the inner tubing is made from a metal.

9. An implantable sensing apparatus comprising:

a substrate comprising an electrode;

an outer tubing surrounding said substrate, said outer tubing having a window opening;

an enzyme aligned between said electrode and said window opening;

a hydrogel layer sealing said window opening; and

a bonding layer between said enzyme and said hydrogel layer, said bonding layer being a different material from said enzyme;

wherein the bonding layer comprises a protein, human serum albumin (HSA), or a polypeptide.

10. The apparatus of claim 9, wherein said bonding layer comprises a protein.

11. The apparatus of claim 9, wherein said bonding layer comprises human serum albumin (HSA).

12. The apparatus of claim 9, wherein said bonding layer comprises a polypeptide.

13. The apparatus of claim 9, wherein said bonding layer comprises an adhesive.

14. The apparatus of claim 9, wherein the outer tubing is coated with a lubricious coating.

15. The apparatus of claim 14, wherein the lubricious coating is siloxane.

16. The apparatus of claim 9, further comprising an inner tubing disposed within an interior of the outer tubing.

17. The apparatus of claim 16, wherein the inner tubing is made from an elastomeric material.

18. The apparatus of claim 16, wherein the inner tubing is made from a metal.

19. The apparatus of claim 9, wherein the enzyme comprises a protein matrix.

20. The apparatus of claim 9, wherein said bonding layer is free of said enzyme.

21. The apparatus of claim 9, wherein said bonding layer is chemically free of said enzyme.

22. The apparatus of claim 9, wherein said bonding layer is only on one side of said enzyme.

23. The apparatus of claim 9, wherein said bonding layer prevents said enzyme from directly contacting said hydrogel layer.

24. An implantable sensing apparatus comprising:

a substrate comprising an electrode;

a spacing element adjacent to said substrate;

an outer tubing surrounding said substrate and said spacing element, said outer tubing having a window opening, wherein geometrical tolerances between said outer tubing and one or more of said spacing element and said substrate define one or more voids;

a backfill structure filling said one or more voids, said backfill structure comprising a curable, implantable material;

an enzyme aligned between said electrode and said window opening, said enzyme being pre-treated with a reducing agent;

a layer of hydrogel sealing said window above said enzyme; and

a layer of protein bonding said enzyme to said layer of hydrogel.

25. The apparatus of claim 24, wherein the outer tubing is coated with a lubricious coating.

26. The apparatus of claim 25, wherein the lubricious coating is siloxane.

27. The apparatus of claim 24, further comprising an inner tubing disposed within an interior of the outer tubing.

28. The apparatus of claim 27, wherein the inner tubing is made from an elastomeric material.

29. The apparatus of claim 27, wherein the inner tubing is made from a metal.

30. The apparatus of claim 24, wherein the enzyme comprises a protein matrix.