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