System and method for attenuating the effect of ambient light on an optical sensor

• US 20060092421A1
• Filed: 10/21/2005
• Published: 05/04/2006
• Est. Priority Date: 04/15/2003
• Status: Active Grant

• Current Assignee: Senseonics, Incorporated (Senseonics Holdings, Inc.)
• Original Assignee: Sensors For Medicine and Science Incorporated
• Inventors: O'Connor, Casey J., Zerwekh, Paul Samuel, Lesho, Jeffrey C., Walters, Steven J., Lorenz, Carrie R., Colvin, Arthur E., Lynn, Robert William
• Granted Patent: US 7,227,156 B2
• Time in Patent Office: Days
• US Class Current: 356/411
• 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 5/14556 by fluorescence A61B5/14555 takes precedence
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 2201/1244 Ambient light detector, e.g. for invalidating
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/086 for inductive purposes, e.g. printed inductor with ferrite core
• CPC Class Codes: H05K 2201/09972 Partitioned, e.g. portions of a PCB dedicated to different functions; Boundary lines therefore; Portions of a PCB being processed separately or differently
• CPC Class Codes: H05K 2201/10106 Light emitting diode [LED]
• CPC Class Codes: H05K 3/403 Edge contacts; Windows or holes in the substrate having plural connections on the walls thereof H05K3/4092 takes precedence

Abstract

The present invention provides systems and methods for attenuating the effect of ambient light on optical sensors and for measuring and compensating quantitatively for the ambient light.

Claims

1. A sensor, comprising:

a housing;

a circuit board housed within the housing, the circuit board having a hole created there through and defining a passageway from a top surface of the circuit board to a bottom surface of the circuit board;

at least one photodetector mounted to the bottom surface of the circuit board, the at least one photodetector having a light sensitive surface, said light sensitive surface being positioned so that light traveling through said passageway can strike said light sensitive surface.

2. The sensor of claim 1, wherein the circuit board is constructed from a material that does not propagate stray light.

3. The sensor of claim 1, wherein the circuit board comprises ferrite.

4. The sensor of claim 1, further comprising an optical filter, wherein at least a portion of said optical filter is disposed within said passageway.

5. The sensor of claim 4, wherein the optical filter is a high pass filter.

6. The sensor of claim 4, further comprising a second optical filter disposed in series with the first optical filter.

7. The sensor of claim 6, wherein the second optical filter is a NIR filter.

8. The sensor of claim 1, further comprising a light source mounted to the top surface of the circuit board.

9. The sensor of claim 1, further comprising a light blocking material disposed to prevent light from striking one or more sides of said at least one photodetector.

10. The sensor of claim 9, wherein the light blocking material comprises a black epoxy.

11. The sensor of claim 1, further comprising a plurality of indicator molecules mounted on an outer surface of the housing.

12. The sensor of claim 11, wherein the indicator molecules are contained within a polymer matrix layer that is disposed on the outer surface of the housing.

13. The sensor of claim 12, wherein the polymer matrix layer is highly porous.

14. The sensor of claim 11, further comprising a light source housed within said housing for illuminating the indicator molecules.

15. The sensor of claim 14, wherein the light source is mounted on the top surface of the circuit board.

16. The sensor of claim 14, further comprising:

means for capturing a first signal output from the at least one photodetector while the indicator molecules are in a fluorescent state, wherein said first signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector; and

means for capturing a second signal output from the at least one photodetector while the indicator molecules are not being illuminated, wherein said second signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector.

17. The sensor of claim 16, further comprising means for generating a third signal, wherein the third signal is a function of the first and second signal.

18. The sensor of claim 17, wherein the means for generating the third signal comprises means for subtracting the second signal from the first signal.

19. The sensor of claim 16, further comprising a transmitter for transmitting the first and second signal to a sensor reader.

20. The sensor of claim 16, further comprising means for activating a light source by driving the light source with about 2 milliamps of current.

21. A sensor, comprising:

a housing;

a ferrite circuit board housed within the housing;

at least one photodetector mounted on the circuit board;

a light source housed within the housing;

a transmitter housed within the housing; and

a plurality of indicator molecules disposed on an outer surface of the housing.

22. The sensor of claim 21, wherein the circuit board has a hole defining a passageway from a top surface of the circuit board to a bottom surface of the circuit board.

23. The sensor of claim 22, wherein the at least one photodetector is mounted to the bottom surface of the circuit board, the at least one photodetector having a light sensitive surface, said light sensitive surface being positioned so that light traveling through said passageway can strike said light sensitive surface.

24. The sensor of claim 23, further comprising an optical filter, wherein at least a portion of said optical filter is disposed within said passageway.

25. The sensor of claim 24, wherein the optical filter is a high pass filter.

26. The sensor of claim 24, further comprising a second optical filter disposed in series with the first optical filter.

27. The sensor of claim 26, wherein the second optical filter is a NIR filter.

28. The sensor of claim 23, wherein the light source is mounted on a top surface of the circuit board.

29. The sensor of claim 21, further comprising a light blocking material disposed to prevent light from striking one or more sides of said at least one photodetector.

30. The sensor of claim 29, wherein the light blocking material comprises a black epoxy.

31. The sensor of claim 21, wherein the indicator molecules are contained within a polymer matrix layer that is disposed on the outer surface of the housing.

32. The sensor of claim 31, wherein the polymer matrix layer is highly porous.

33. The sensor of claim 21, further comprising:

means for capturing a first signal output from the at least one photodetector while the indicator molecules are in a fluorescent state, wherein said first signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector; and

means for capturing a second signal output from the at least one photodetector while the indicator molecules are not being illuminated, wherein said second signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector.

34. The sensor of claim 33, further comprising means for generating a third signal, wherein the third signal is a function of the first and second signal.

35. The sensor of claim 34, wherein the means for generating the third signal comprises means for subtracting the second signal from the first signal.

36. The sensor of claim 33, further comprising a transmitter for transmitting the first and second signal to a sensor reader.

37. The sensor of claim 33, further comprising means for activating a light source by driving the light source with about 2 milliamps of current.

38. A sensor, comprising:

a housing;

at least one photodetector housed within the housing;

a light source housed within the housing;

a transmitter housed within the housing; and

a plurality of indicator molecules contained within a polymer matrix layer that is disposed on an outer surface of the housing, wherein the polymer matrix layer is highly porous.

39. The sensor of claim 38, further comprising a circuit board housed within the housing, wherein the at least one photodetector is mounted on the circuit board.

40. The sensor of claim 39, wherein the circuit board is a ferrite circuit board.

41. The sensor of claim 39, wherein the circuit board has a hole defining a passageway from a top surface of the circuit board to a bottom surface of the circuit board, and the photodetector has at least one photosensitive surface that is positioned so that light traveling through said passageway can strike said light sensitive surface.

42. The sensor of claim 41, further comprising an optical filter, wherein at least a portion of said optical filter is disposed within said passageway.

43. The sensor of claim 42, wherein the optical filter is a high pass filter.

44. The sensor of claim 42, further comprising a second optical filter disposed in series with the first optical filter.

45. The sensor of claim 44, wherein the second optical filter is a NIR filter.

46. The sensor of claim 41, wherein the light source is mounted on the top surface of the circuit board and the at least one photodetector is mounted on the bottom surface of the circuit board.

47. The sensor of claim 38, further comprising a light blocking material disposed to prevent light from striking one or more sides of said at least one photodetector.

48. The sensor of claim 47, wherein the light blocking material comprises a black epoxy.

49. The sensor of claim 38, further comprising:

means for capturing a first signal output from the at least one photodetector while the indicator molecules are in a fluorescent state, wherein said first signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector; and

means for capturing a second signal output from the at least one photodetector while the indicator molecules are not being illuminated, wherein said second signal is a function of the intensity of the light striking a photosensitive surface or surfaces of the at least one photodetector.

50. The sensor of claim 49, further comprising means for generating a third signal, wherein the third signal is a function of the first and second signal.

51. The sensor of claim 49, wherein the means for generating the third signal comprises means for subtracting the second signal from the first signal.

52. The sensor of claim 49, further comprising a transmitter for transmitting the first and second signal to a sensor reader.

53. The sensor of claim 49, further comprising means for activating a light source by driving the light source with about 2 milliamps of current.