Optical sensor with radioluminescent light source

• US 5,708,957 A
• Filed: 02/02/1996
• Issued: 01/13/1998
• Est. Priority Date: 02/02/1996
• Status: Expired due to Term

• Current Assignee: University of Iowa Research Foundation
• Original Assignee: University of Iowa Research Foundation
• Inventors: Chuang, Han, Arnold, Mark A.
• Primary Examiner(s): Le, Long V.
• Application Number:
  US08/597,509
• Time in Patent Office: 711 Days
• Field of Search: 422/68.1, 422/82.05, 422/82.07, 422/82.08, 422/82.09, 422/82.11, 436/57, 436/164, 436/127, 436/68, 436/75, 436/145, 436/163, 436/166, 436/172, 436/800, 252/646, 252/301.4 P
• US Class Current: 422/82.07
• CPC Class Codes: C09K 11/04 containing natural or artificial radioactive elements or unspecified radioactive elements
• CPC Class Codes: G01N 2021/7786 Fluorescence
• 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: Y10T 436/20 Oxygen containing
• CPC Class Codes: Y10T 436/23 Carbon containing

Abstract

An optical sensor is disclosed which uses a radioluminescent light source to supply the incident radiation for detecting a selected substance in a test medium. The radioluminescent source includes a beta emitting radio isotope which energizes a co-immobilized luminophore to release light in a given wavelength for a chemical sensor operation. The radioluminescent source is coupled with a sensing matrix for detecting and quantifying the analyte of interest. The sensing matrix produces a characteristic signal based on either absorbance or fluorescence which varies according to the concentration of the selected analyte in the sample. A photodetector measures the resulting optical signal from which the analyte concentration is determined.

Claims

1. An optical sensor for detecting a selected substance, comprising:

a radioluminescent light source, including;

a radioactive constituent,

a phosphor constituent energized by radiation from said radioactive constituent to emit light;

a sensing matrix absorbing light from said radioluminescent light source to produce an optical characteristic, the optical characteristic changing upon exposure of said sensing matrix to the selected substance; and

a photodetector configured to detect the optical characteristic and provide a corresponding signal to indicate detection of the selected substance.

2. The optical sensor of claim 1, wherein:

said radioactive constituent includes a beta particle emitter; and

said sensing matrix has a luminophore portion.

3. The optical sensor of claim 2, wherein the selected substance includes O₂, said phosphor constituent includes ZnS:

Ag, said luminophore portion includes a ruthenium complex fluorophore, and the optical characteristic includes fluorescence.

4. The optical sensor of claim 2, wherein the selected substance is pH of a solution, said phosphor constituent includes Y₂ O₂ S:

Eu, said luminophore portion includes Merck N9, and the optical characteristic includes color of said sensing matrix.

5. The optical sensor of claim 2, wherein the selected substance is CO₂, said phosphor constituent includes Y₃ (Al,Ga)₅ O₁₂ :

Ce, said luminophore portion includes m-cresol purple, and the optical characteristic includes color of said sensing matrix.

6. The optical sensor of claim 1, wherein said sensing matrix has a luminophore portion and said luminophore portion includes a compound selected from the group consisting of:

Ru(dpp)₃ ;

Ru(phen)₃ ;

Merck N9; and

m-cresol purple.

7. The optical sensor of claim 1, wherein said radioactive constituent includes one of ³ H, ¹⁴ C, and ¹⁴⁷ Pm and said phosphor constituent includes one of Y₂ O₂ S:

Eu, Y₃ (Al,Ga)₅ O₁₂ ;

Ce, and ZnS;

Ag.

22. The optical sensor of claim 1, wherein said sensing matrix is spaced apart from said radioluminescent light source to define a test cell therebetween.

8. An optical sensing system for detecting concentration of a selected substance in a test medium, comprising:

a radioluminescent source emitting light;

a sensing matrix exposed to the test medium, said sensing matrix absorbing light from said radioluminescent source to produce an optical characteristic, the optical characteristic varying in accordance with concentration of the selected substance in the test medium; and

a photodetector configured to detect the optical characteristic and provide a corresponding signal to indicate concentration of the selected substance in the test medium.

9. The optical sensing system of claim 8, wherein said radioluminescent source includes:

a radioactive material emitting beta particles; and

a phosphor material energized by beta particles from said radioactive material to emit light.

10. The optical sensing system of claim 8, wherein said photodetector includes a photodiode.

11. The optical sensing system of claim 8, wherein said photodetector includes a photomultiplier tube.

12. The optical sensing system of claim 8, further comprising an optical filter positioned between said sensing matrix and one of said radioluminescent source and said photodetector.

13. The optical sensing system of claim 8, further comprising a container enclosing said radioluminescent source, said container being positioned to define a test cell between said sensing matrix and said radioluminescent source, and said test cell being configured to receive the test medium.

14. The optical sensing system of claim 13, wherein said photodetector includes a photodiode, said sensing matrix includes a membrane coupled to the photodetector, said membrane has a surface exposed to the test medium, and further comprising:

a first light filter positioned between said container and said test cell;

a second light filter positioned between said membrane and said photodetector; and

a signal processing subsystem electrically coupled to said photodetector, said signal processing subsystem including a display for providing a indication of the substance concentration to an operator.

15. The optical sensing system of claim 8, further comprising:

a probe housing said radioluminescent source, said probe having;

an outer surface coupled to said sensing matrix, said sensing matrix having a sensing surface configured to contact said test medium,

a mirror adjacent said radioluminescent source to reflect electromagnetic radiation emitted therefrom,

a body configured to transmit light from said radioluminescent source to said sensing matrix;

an optical fiber coupling said probe to said photodetector, said optical fiber and said probe being configured to transmit electromagnetic radiation from said sensing matrix to said photodetector;

an optical filter positioned between said photodetector and said radioluminescent source; and

a coating covering at least a portion of said sensing surface to prevent intrusion of ambient light.

23. The optical sensor of claim 8, wherein said sensing matrix includes a film containing a fluorophore configured to detect oxygen, and said film is spatially separated from said radioluminescent light source.

16. An optical sensor for detecting a selected substance in a test medium, comprising:

a radioluminescent source emitting light;

a sensing matrix having a fluorophore portion, said sensing matrix being exposed to the test medium, said sensing matrix providing a fluorescent emission in response to absorption of light from said radioluminescent source; and

a photodetector detecting a first intensity of the fluorescent emission when the test medium does not include the selected substance and said photodetector detecting a second intensity of the fluorescent emission when the test medium includes the selected substance, said second intensity differing from said first intensity.

17. The optical sensor of claim 16, wherein said fluorophore portion includes a ruthenium complex.

18. The optical sensor of claim 16, wherein said fluorophore portion includes a PAH compound.

19. The optical sensor of claim 16, wherein said sensing matrix includes one of:

Ru(dpp)₃ in a polystyrene membrane;

Ru(dpp)₃ in a sol-gel membrane; and

Ru(phen)₃ in a silicone membrane.

20. The optical sensor of claim 16, wherein said radioluminescent source includes:

a radioactive constituent emitting beta particles; and

a phosphor constituent emitting light in response to beta particles from said radioactive constituent.

21. The sensor of claim 16, further comprising:

a container for enclosing said radioluminescent source and being configured to transmit light from said radioluminescent source to said sensing matrix; and

a coupling means for positioning said sensing matrix relative to said container, said photodetector, and the test medium.

24. The optical sensor of claim 16, wherein said sensing matrix includes a film with said fluorophore portion, and said film is spatially separated from said radioluminescent light source.

25. An optical sensing system for detecting a selected substance, comprising:

a radioluminescent light source, including;

a radioactive constituent,

a phosphor constituent energized by radiation from said radioactive constituent to emit light;

a sensing matrix absorbing light from said radioluminescent light source, said sensing matrix being defined separately from said radioluminescent light source to produce an optical characteristic, said optical characteristic changing upon exposure of said sensing matrix to the selected substance; and

a photodetector configured to detect the optical characteristic and provide a corresponding signal to indicate detection of the selected substance.

26. The system of claim 25, wherein said radioluminescent light source and said sensing matrix are spaced apart from each other to define a test cell therebetween.

27. The system of claim 25, wherein said sensing matrix includes a film containing a luminophore and said film is spaced apart from said radioluminescent light source.

28. The system of claim 25, further comprising a probe housing said radioluminescent source, said probe having:

an outer surface coupled to said sensing matrix, said sensing matrix having a sensing surface configured to contact a test medium; and

a body configured to transmit light from said radioluminescent source to said sensing matrix, at least a portion of said body being positioned between said sensing matrix and said radioluminescent source.

29. The system of claim 28, wherein said probe includes a mirror to reflect electromagnetic radiation emitted from said radioluminescent light source.

30. The system of claim 29, further comprising an optical fiber coupling said probe to said photodetector, said probe being configured to transmit electromagnetic radiation from said sensing matrix to said photodetector.

31. The system of claim 25, wherein said sensing matrix includes a ruthenium complex configured to detect oxygen.

32. The system of claim 25, wherein said radioactive constituent includes at least one of ³ H or ¹⁴⁷ Pm.

33. The system of claim 25, wherein said phosphor constituent includes at least one of Y₂ O₂ S:

Eu, Y₃ (Al,Ga)₅ O₁₂ ;

Ce, or ZnS;

Ag.