IMPLANTABLE OPTICAL SENSOR AND METHOD FOR MANUFACTURE

• US 20090156912A1
• Filed: 12/12/2007
• Published: 06/18/2009
• Est. Priority Date: 12/12/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Knowles, Shawn D., Kuhn, Jonathan L., Cinbis, Can, Ecker, Robert M., Davis, Timothy J.
• Granted Patent: US 8,275,432 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive

Abstract

An implantable optical sensor and associated manufacturing method include a sensor housing having an inner surface and an outer surface and a window formed in the housing extending between the housing inner surface and the housing outer surface. An opto-electronic device enclosed within the housing and having a photonic surface is operatively positioned proximate the window for emitting light through the window or detecting light through the window. An optical coupling member is positioned between the opto-electronic device and the window for reducing light reflection at a surface within the implantable optical sensor.

Claims

1. An implantable medical device, comprising:

a housing having an inner surface and an outer surface;

a window formed in the housing extending between the housing inner surface and the housing outer surface;

an opto-electronic device enclosed within the housing and having a photonic surface operatively positioned proximate the window for one of emitting light through the window and detecting light through the window; and

a first optical coupling member positioned between the opto-electronic device and the window to reduce light reflection at a surface within the implantable medical device.

2. The implantable medical device of claim 1 wherein the first optical coupling member comprises an optical substrate, the opto-electronic device being mounted on the substrate.

3. The implantable medical device of claim 2 wherein the substrate is coupled to the housing inner surface along the window.

4. The implantable medical device of claim 2 wherein the window comprises an optical lens coupled to the housing, the lens having an inner surface, and wherein the substrate is coupled to the lens inner surface.

5. The implantable medical device of claim 1 wherein the window comprises an optical lens coupled to the housing, the lens having an inner surface, and wherein the first optical coupling member is coupled to the lens inner surface to reduce light reflection at the lens inner surface.

6. The implantable medical device of claim 1 further comprising:

a substrate, the opto-electronic device mounted on the substrate; and

an enclosure surrounding the opto-electronic device and coupled to the substrate, the enclosure extending from the substrate to the window, wherein the first optical coupling member comprises an optical material filling at least a portion of the enclosure and embedding the photonic surface of the opto-electronic device to reduce reflection of light at the photonic surface.

7. The implantable medical device of claim 6 wherein the substrate includes a port through which the material is introduced into the enclosure.

8. The implantable medical device of claim 6 wherein the first optical coupling member is a pre-formed member.

9. The implantable medical device of claim 6 wherein the optical material has a first coefficient of thermal expansion and the enclosure has a second coefficient of thermal expansion greater than the first coefficient of thermal expansion, and wherein the optical material is compressed within the enclosure after cooling the enclosure and the optical material from a temperature corresponding to a curing temperature of the optical material.

10. The implantable medical device of claim 9 wherein the medical device further comprises a pressure relief member to receive a portion of the compressed material.

11. The implantable medical device of claim 6 further comprising a second optical coupling member positioned between the first optical coupling member and the window, wherein the window comprises an optical lens coupled to the housing and having an inner surface, and wherein the second optical coupling member reduces light reflection at the lens inner surface.

12. The implantable medical device of claim 10 wherein the second optical coupling member has a first durometer and the first optical coupling member has a second durometer greater than the first durometer, the second optical coupling member forming an interference fit between the lens and the first optical coupling member.

13. The implantable medical device of claim 11 wherein the second optical coupling member is one of a preformed member and an optical gel.

14. The implantable medical device of claim 11 wherein the index of refraction of the second optical coupling member approximately matches the index of refraction of the first optical coupling member.

15. The implantable medical device of claim 11 wherein the second optical coupling member is coupled to the lens inner surface, the second optical coupling member has an inner surface separated from the first optical coupling member, the first optical coupling member has a first index of refraction and the second optical coupling member has a second index of refraction lower than the first index of refraction.

16. The implantable medical device of claim 1 wherein the first optical coupling member comprises a cup-shaped member and an optical material filling the cup-shaped member, the photonic surface being embedded within the optical material for reducing light reflection at the photonic surface.

17. The implantable medical device of claim 1 wherein the window comprises:

a lens having an inner and outer surface; and

a seal formed over the lens outer surface, wherein the seal is formed from an optical polymer having an index of refraction selected to reduce reflection of light at the lens outer surface.

18. The implantable medical device of claim 1 further comprising conductors extending from the opto-electronic device, wherein the conductors are insulated from the housing inner surface by the optical coupling member.

19. The implantable medical device of claim 18 wherein the photonic surface is approximately 15 mils or less from the housing inner surface.

20. An implantable medical device, comprising:

a housing;

a light emitting portion comprising a first window formed in the housing and a light emitting device operatively positioned within the housing for transmitting light through the first window;

a light detecting portion comprising a second window formed in the housing and a light detecting device operatively positioned within the housing for receiving light transmitted through the second window; and

means for reducing light reflection occurring at a surface within the implantable medical device as compared to light reflection occurring at the surface when the surface is interfaced with air.

21. A method for manufacturing an implantable optical sensor, comprising:

enclosing an opto-electronic device within a housing having an inner surface and an outer surface, the opto-electronic device having a photonic surface and being positioned in operative relation to a window extending between the housing inner surface and the housing outer surface, the opto-electronic device configured for one of emitting light and detecting light through the window; and

positioning a first optical coupling member between the opto-electronic device and the window to reduce light reflection at a surface within the implantable optical sensor.

22. The method of claim 21 wherein the first optical coupling member comprises an optical substrate and further comprising mounting the opto-electronic device on the optical substrate.

23. The method of claim 22 further comprising coupling the optical substrate to the housing inner surface.

24. The method of claim 22 wherein the window comprises an optical lens coupled to the housing, the lens having an inner surface, and further comprising coupling the optical substrate to the lens inner surface.

25. The method of claim 21 wherein the window comprises an optical lens coupled to the housing, the lens having an inner surface, the method further comprising coupling the first optical coupling member to the lens inner surface to reduce light reflection at the lens inner surface.

26. The method of claim 21 wherein the first optical coupling member is a preformed member.

27. The method of claim 21 further comprising:

mounting the opto-electronic device on a substrate;

coupling an enclosure to the substrate, the enclosure surrounding the opto-electronic device and extending from the substrate to the window; and

filling at least a portion of the enclosure with a material for forming the first optical coupling member, the material embedding the photonic surface of the opto-electronic device to reduce light reflection at the photonic surface.

28. The method of claim 27 wherein filling at least a portion of the enclosure includes introducing the material through a port in the substrate.

29. The method of claim 27 further comprising:

heating the enclosure and the material to a temperature corresponding to a curing temperature of the material; and

cooling the enclosure and the material from the temperature,

wherein the material has a first coefficient of thermal expansion and the enclosure has a second coefficient of thermal expansion greater than the first coefficient of thermal expansion such that the material becomes compressed within the enclosure upon cooling.

30. The method of claim 29 wherein the sensor comprises a pressure relief member to receive a portion of the compressed material.

31. The method of claim 27 further comprising positioning a second optical coupling member between the first optical coupling member and the window, wherein the window comprises an optical lens coupled to the housing, the optical lens having an inner surface, and wherein the second optical coupling member reduces light reflection at the lens inner surface.

32. The method of claim 31 wherein the second optical coupling member has a first durometer and the first optical coupling member has a second durometer greater than the first durometer, the second optical coupling member forming an interference fit between the lens and the first optical coupling member.

33. The method of claim 31 wherein the second optical coupling member is one of a preformed member and an optical gel.

34. The method of claim 31 wherein the index of refraction of the second optical coupling member approximately matches the index of refraction of the first optical coupling member.

35. The method of claim 31 further comprising coupling the second optical coupling member to the lens inner surface, the second optical coupling member having an inner surface separated from the first optical coupling member, the first optical coupling member having a first index of refraction and the second optical coupling member having a second index of refraction lower than the first index of refraction.

36. The method of claim 21 wherein positioning the first optical coupling member comprises:

positioning the opto-electronic device in a cup-shaped member; and

embedding the photonic surface of the opto-electronic device in an optical material by filling the cup-shaped member with the optical material.

37. The method of claim 21 wherein the window comprises a lens having an outer surface and further comprising forming a seal over the lens outer surface, the seal formed of an optical polymer having an index of refraction selected to reduce light reflection at the lens outer surface.

38. The method of claim 21 wherein conductors extend from the opto-electronic device, and the first optical coupling member electrically insulates the conductors from the housing inner surface.

39. The method of claim 38 wherein the photonic surface is positioned approximately 15 mils or less from the housing inner surface.