Optimized sensor geometry for an implantable glucose sensor

• US 7,881,763 B2
• Filed: 05/02/2006
• Issued: 02/01/2011
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Tapsak, Mark A., Martinson, Laura A., Brauker, James H., Carr-Brendel, Victoria, Neale, Paul V.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US11/415,631
• Publication Number:
  US 20060211921A1
• Time in Patent Office: 1,736 Days
• Field of Search: 600/309, 600/300, 600/316, 600/322, 600/345, 600/347, 600/365
• US Class Current: 600/345
• CPC Class Codes: A61B 2562/187 Strain relief means
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/415 the glands, e.g. tonsils, adenoids or thymus
• CPC Class Codes: A61B 5/418 lymph vessels, ducts or nodes
• CPC Class Codes: A61B 5/6882 Anchoring means

Abstract

An implantable sensor for use in measuring a concentration of an analyte such as glucose in a bodily fluid, including a body with a sensing region adapted for transport of analytes between the sensor and the bodily fluid, wherein the sensing region is located on a curved portion of the body such that when a foreign body capsule forms around the sensor, a contractile force is exerted by the foreign body capsule toward the sensing region. The body is partially or entirely curved, partially or entirely covered with an anchoring material for supporting tissue ingrowth, and designed for subcutaneous tissue implantation. The geometric design, including curvature, shape, and other factors minimize chronic inflammatory response at the sensing region and contribute to improved performance of the sensor in vivo.

Claims

1. An implantable sensor for use in measuring a concentration of an analyte in a bodily fluid, the sensor comprising:

a body comprising an electrochemical sensing region adapted for transport of an analyte between the electrochemical sensing region and a bodily fluid, wherein the electrochemical sensing region comprises one or more electrodes, wherein the body comprises a first major surface and a second major surface, wherein the one or more electrodes are situated approximately at a center of the first major surface, wherein the electrochemical sensing region is located on a curved portion of the first major surface configured such that when a foreign body capsule forms around the sensor, a contractile force is exerted by the foreign body capsule toward the sensing region, and wherein the sensor is a subcutaneous sensor configured for implantation in a soft tissue of a host.

2. The sensor of claim 1, wherein the electrochemical sensing region comprises a plurality of electrodes.

3. The sensor of claim 1, wherein the second major surface is flat.

4. The sensor of claim 1, wherein the second major surface has a curvature.

5. The sensor of claim 1, wherein the first major surface, when viewed from a direction perpendicular to a center of the first major surface, has a substantially oval profile.

6. The sensor of claim 1, wherein the first major surface, when viewed from a direction perpendicular to a center of the first major surface, has a substantially circular profile.

7. The sensor of claim 1, wherein at least one of the first major surface or the second major surface has a non-electrode surface area comprising an anchoring material for supporting tissue ingrowth.

8. The sensor of claim 1, further comprising a mechanical anchoring mechanism formed on the body.

9. The sensor of claim 1, wherein the curved portion of the first major surface has a plurality of radii of curvature.

10. The sensor of claim 1, wherein the curved portion of the first major surface has a radius of curvature of from about 0.5 mm to about 10 cm.

11. The sensor of claim 1, wherein the first major surface and the second major surface together account for at least about 40% of the surface area of the body.

12. The sensor of claim 1, wherein edges of the first major surface are rounded and transition smoothly away from the first major surface.

13. The sensor of claim 1, wherein the body defines a surface area, and wherein from 10% to 100% of the surface area is convexly curved.

14. The sensor of claim 1, wherein the body comprises plastic.

15. The sensor of claim 14, wherein the plastic is selected from the group consisting of thermoplastic and thermoset.

16. The sensor of claim 15, wherein the thermoset is selected from the group consisting of epoxy, silicone, and polyurethane.

17. The sensor of claim 1, wherein the body comprises a material selected from the group consisting of metal, ceramic, and glass.

18. The sensor of claim 1, further comprising a porous biointerface material that covers at least a portion of the sensing region.

19. The sensor of claim 18, wherein the biointerface material comprises interconnected cavities dimensioned and arranged to interfere with formation of occlusive cells.

20. The sensor of claim 1, wherein the sensor is a glucose sensor.

21. The sensor of claim 1, wherein the electrochemical sensing region comprises a multi-region membrane covering one or more of the one or more electrodes.

22. The sensor of claim 21, wherein the multi-region membrane comprises an enzyme.

23. The sensor of claim 1, wherein the first major surface and the second major surface together account for at least about 50% of a total surface area of the body.

24. The sensor of claim 1, wherein the electrochemical sensing region comprises a silicone-containing material covering one or more of the one or more electrodes.

25. A wholly implantable sensor adapted to measure a concentration of an analyte in a bodily fluid, comprising:

a wholly implantable body comprising an electrochemical sensing region comprising one or more electrodes, wherein the one or more electrodes are located on a curved portion of a first major surface of the body, wherein the body further comprises a second major surface, wherein the sensing region is situated approximately at a center of the first major surface, wherein the sensor is a subcutaneous sensor suitable for implantation in a soft tissue of a host, and wherein a non-electrode surface area of the body comprises a porous anchoring material for supporting tissue ingrowth.

26. The sensor of claim 25, wherein the electrochemical sensing region comprises a plurality of electrodes.

27. The sensor of claim 25, wherein the electrochemical sensing region comprises a multi-region membrane covering one or more of the one or more electrodes.

28. The sensor of claim 27, wherein the multi-region membrane comprises an enzyme.

29. The sensor of claim 25, wherein the first major surface and the second major surface together account for at least about 50% of the surface area of the body.

30. The sensor of claim 25, wherein a non-electrode surface area of the body comprises a porous anchoring material for supporting tissue ingrowth.

31. The sensor of claim 25, wherein the electrochemical sensing region comprises a silicone-containing material covering one or more of the one or more electrodes.

32. The sensor of claim 25, wherein the curved portion of the first major surface has a plurality of radii of curvature.

33. The sensor of claim 25, wherein the curved portion of the first major surface has a radius of curvature of from about 0.5 mm to about 10 cm.

34. The sensor of claim 25, wherein the sensor is a glucose sensor.

35. An implantable sensor adapted to measure a concentration of an analyte in a bodily fluid, comprising:

a body having a first major surface and, opposite thereto, a second major surface, wherein the first major surface is generally planar, slightly convex, and has rounded edges, with an electrochemical sensing region comprising one or more electrodes located on the first major surface, wherein the electrochemical sensing region is spaced away from the rounded edges and approximately at a center of the first major surface, wherein the electrochemical sensing region comprises a silicone-containing material, wherein the first major surface is configured to be sufficiently convex that when a foreign body capsule forms around the sensor, contractile forces are exerted thereby generally uniformly towards the electrochemical sensing region, and wherein the sensor is a subcutaneous sensor configured for implantation in a soft tissue of a host.

36. The sensor of claim 35, wherein the electrochemical sensing region comprises a plurality of electrodes.

37. The sensor of claim 35, wherein the electrochemical sensing region comprises a multi-region membrane covering one or more of the one or more electrodes.

38. The sensor of claim 37, wherein the multi-region membrane comprises an enzyme.

39. The sensor of claim 35, wherein the first major surface and the second major surface together account for at least about 50% of the surface area of the body.

40. The sensor of claim 35, wherein a non-electrode surface area of the body comprises a porous anchoring material for supporting tissue ingrowth.

41. The sensor of claim 35, wherein the electrochemical sensing region comprises a silicone-containing material covering one or more of the one or more electrodes.

42. The sensor of claim 35, wherein the first major surface has a plurality of radii of curvature.

43. The sensor of claim 35, wherein the first major surface has a radius of curvature of from about 0.5 mm to about 10 cm.

44. The sensor of claim 35, wherein the sensor is a glucose sensor.