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

• US 20070078319A1
• Filed: 11/30/2006
• Published: 04/05/2007
• 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
• Granted Patent: US 7,912,525 B2
• Time in Patent Office: Days
• 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 sensor module having internal elements, a portion of said sensor module having an outer dimension;

an outer tubing surrounding said sensor module, said outer tubing having an inner dimension, said inner dimension of said outer tubing and said outer dimension of said portion of said sensor module being substantially the same, but defining at least one void between said inner dimension of said outer tubing and said outer dimension of said portion of said sensor module due to inherent manufacturing tolerances; and

back-fill material disposed in said at least one void.

2. The apparatus of claim 1, wherein said internal elements comprise a substrate having an electrode.

3. The apparatus of claim 2, wherein said internal elements further comprise a bead structure formed adjacent to one or more ends of said substrate.

4. The apparatus of claim 3, wherein said internal elements further comprise a spacing element adjacent to said substrate.

5. The apparatus of claim 1, wherein said backfill material comprises a curable, implantable material.

6. The apparatus of claim 5, wherein said curable, implantable material comprises one or more of:

silicone;

epoxy; and

bone cement.

7. The apparatus of claim 5, wherein said curable, implantable material comprises a foam.

8. The apparatus of claim 5, wherein said curable, implantable material comprises a gel.

9. The apparatus of claim 5, wherein said curable, implantable material comprises an adhesive.

10. The apparatus of claim 1, wherein said back-fill material comprises a flowable material injected into said voids, and subsequently cured to a non-flowable state.

11. The apparatus of claim 1, wherein said back-fill material comprises a pre-molded structure.

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

13. The apparatus of claim 1, wherein the lubricious coating is siloxane.

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

15. The apparatus of claim 14, wherein the inner tubing is made from an elastomeric material.

16. The apparatus of claim 14, wherein the inner tubing is made from a metal.

17. The apparatus of claim 1,

wherein said sensor module comprises a substrate for supporting electronics;

and

wherein said outer dimension of said portion of said sensor module is an outer dimension of said substrate.

18. The apparatus of claim 1,

wherein said sensor module comprises:

an electrode; and

a spacing element positioned over said electrode; and

wherein said outer dimension of said portion of said sensor module is an outer dimension of said spacing element.

19. The apparatus of claim 1,

wherein said sensor module comprises:

a substrate; and

a bead attached to an end of said substrate for supporting said substrate; and

wherein said outer dimension of said portion of said sensor module is an outer dimension of said bead.

20. The apparatus of claim 1, wherein said shape of said outer peripheral surface of said portion of said sensor module is a curved shape.

21. The apparatus of claim 1, wherein said outer tubing is dimensioned relative to the sensor module to provide a compression force on the sensor module.

22. The apparatus of claim 1, wherein the sensor module fills a volume within the outer tubing and the at least one void comprises a volume of less than one-fourth the volume of the sensor module.

23. The apparatus of claim 1, wherein the outer tubing has a cross-sectional dimension and the sensor module defines a cross-sectional area within the cross-sectional dimension of the outer tubing and wherein the cross-sectional area of the sensor module is less than one-fourth the cross-sectional dimension of the outer tubing.