Integrally formed surface plasmon resonance sensor

• US 5,912,456 A
• Filed: 03/19/1997
• Issued: 06/15/1999
• Est. Priority Date: 03/19/1996
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Keller, Robert C., Carr, Richard A., Melendez, Jose L.
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US08/820,621
• Time in Patent Office: 818 Days
• Field of Search: 250/216, 250/225, 250/239, 250/208.1, 250/214, 356/369, 359/858, 359/859, 359/834
• US Class Current: 250/216
• CPC Class Codes: G01N 21/553 and using surface plasmons fluorescence excitation G01N21/648; enhanced Raman G01N21/658

Abstract

A surface plasmon resonance sensor includes a light source 10 and a polarizer 18 for producing polarized light which passes through a transparent body 12 and strikes a thin conductive film 26 disposed on the exterior surface of the body 12. The film 26 exhibits surface plasmon resonance when the light strikes the film at a "resonance angle". By determining the angle at which surface plasmon resonance occurs, the refractive index of the material on the side of the film 26 opposite to the side which reflects the polarized light can be measured.

Claims

1. A surface plasmon sensor comprising, in combination:

a source of electromagnetic radiation having a given frequency range;

a housing transparent to said electromagnetic radiation in said frequency range;

a thin surface plasmon resonance layer, the layer having a interior surface disposed on an exterior surface of said housing and an outer surface;

an array of photodetectors disposed closely adjacent the surface of said housing and substantially coplanar with said source;

said surface plasmon resonance layer and said photodetectors being disposed relative to each other so that said radiation from said source reflects off said interior surface and strikes at least some of said photodetectors,

whereby said radiation'"'"'s intensity varies as a function of which said photodetector is struck, said intensity variation function being affected by the index of refraction of a material that comes in contact with said outer surface.

2. The surface plasmon sensor of claim 1 additionally including a thermal sensor disposed in said housing providing a signal for calibrating said surface plasmon sensor.

3. The surface plasmon sensor of claim 1 additionally including a radiation sensor in said housing for sensing the intensity of said electromagnetic radiation for calibrating said surface plasmon sensor.

4. The surface plasmon sensor of claim 1 additionally including at least one mirrored surface disposed between said source of electromagnetic radiation and said photodetectors for modifying the direction of said radiation so that it strikes at least some of said photodetectors.

5. The surface plasmon sensor of claim 2 additionally including a radiation sensor in said housing for sensing the intensity of said electromagnetic radiation for calibrating said surface plasmon sensor.

6. The surface plasmon sensor of claim 1, wherein said source of electromagnetic radiation and said array of photodetectors are mounted upon a common substrate.

7. The surface plasmon sensor of claim 3 additionally including at least one mirrored surface disposed between said source of electromagnetic radiation and said photodetectors for modifying the direction of said radiation so that it strikes at least some of said photodetectors.

8. The surface plasmon sensor of claim 1, wherein said source of electromagnetic radiation is disposed within said housing.

9. The surface plasmon sensor of claim 1 wherein said radiation strikes said photodetectors at an angle between about 60 and 90 degrees.

10. The surface plasmon sensor of claim 4 wherein said radiation strikes said photodetectors at an angle between about 60 and 90 degrees.

11. The surface plasmon sensor of claim 1 additionally including a filter disposed in said housing to prevent radiation other than said radiation from said source from striking said photodetectors.

12. The surface plasmon sensor of claim 11 wherein said filter comprises the material of said housing which is substantially opaque for all radiation to which said photodetectors are sensitive other than said radiation from said source.

13. The surface plasmon sensor of claim 4 wherein each said mirrored surface is disposed on an exterior surface of said housing.

14. The surface plasmon sensor of claim 4 wherein at least one said reflective surface is formed on a curved surface.

15. The surface plasmon sensor of claim 1 wherein the rays of said radiation striking said surface plasmon resonance layer are diverging from each other.

16. The surface plasmon sensor of claim 1 wherein said rays of said radiation striking said surface plasmon resonance layer are converging toward each other.

17. The surface plasmon sensor of claim 1 wherein said rays of said radiation strike said surface plasmon resonance layer substantially parallel to each other.

18. The surface plasmon sensor of claim 1 additionally including a filter disposed adjacent said array of photodetectors for blocking radiation from striking said photodetectors having a frequency different from the frequency of said source of electromagnetic radiation.

19. The surface plasmon sensor of claim 1 additionally including a polarizing filter disposed in the path of said radiation between said source and said array of photodetectors.

20. The surface plasmon sensor of claim 1 wherein the surface on which said surface plasmon resonance layer is formed is a curved surface.

21. The surface plasmon sensor of claim 14 wherein the surface on which said surface plasmon resonance layer is formed is a curved surface.

22. A surface plasmon sensor comprising, in combination:

a source of electromagnetic radiation;

a housing surrounding said source of electromagnetic radiation and transparent to said electromagnetic radiation;

a polarizer disposed in said housing for producing polarized radiation from said electromagnetic radiation;

a thin surface plasmon resonance layer disposed on an exterior surface of said housing;

an array of photodetectors disposed in said housing and substantially coplanar with said source;

the polarized radiation from said polarizer, said surface plasmon resonance layer and said photodetectors being disposed relative to each other so that said polarized radiation reflects off said surface plasmon resonance layer and strikes at least some of said photodetectors.

23. A surface plasmon sensor comprising, in combination:

a housing transparent to electromagnetic radiation in a given frequency range;

a source of electromagnetic radiation in said given frequency range and disposed within said housing;

a polarizer for producing polarized radiation from said electromagnetic radiation and disposed within said housing;

a thin electrically conductive layer disposed on an exterior surface of said housing;

an array of photodetectors disposed closely adjacent the surface of said housing;

the polarized radiation from said polarizer, said electrically conductive layer and said photodetectors being disposed relative to each other so that said polarized radiation reflects off said electrically conductive layer and strikes at least some of said photodetectors.

24. The surface plasmon sensor of claim 23, wherein said thin electrically conductive layer is a surface plasmon resonance layer.