Coaxial Diffuse Reflectance Read Head

• US 20090021743A1
• Filed: 06/16/2005
• Published: 01/22/2009
• Est. Priority Date: 06/17/2004
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Dosmann, Andrew J.
• Granted Patent: US 7,724,374 B2
• Time in Patent Office: Days
• US Class Current: 356/446
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/8483 Investigating reagent band test-element handling not specific to a test method G01N33/4875; analytical elements specific to chemical analysis of biological material G01N33/52; autometer with reagent band G01N35/04

Abstract

Improved performance in reflectance photometry is obtained by employing an optical fiber to direct collimated light to a test area and to return both diffuse and specular light from the test area. Specular light is prevented from reaching a light detector by a spatial filter, while diffuse light is collected and measured.

Claims

1. A coaxial diffuse reflectance read head comprising:

(a) a collimated light source;

(b) a beam splitter adapted to receive collimated light from said collimated light source and adapted to direct a portion of said collimated light to an optical fiber;

(c) an optical fiber adapt to direct said collimated light received from said beam splitter at one end of said optical fiber to a test area at a second end of said optical fiber and adapted to direct specular and diffuse light returned from said test area to said beam splitter, said optical fiber being either in contact with said test area or closely approaching said test area; and

(d) a spatial filter adapted to receive said specular light from said beam splitter and to block access of said specular light to a light detector.

2. The coaxial diffuse reflectance read head of claim 1, further comprising a light detector disposed behind said spatial filter adapted to receive diffuse light from said beam splitter and to produce an electrical signal from said diffuse light.

3. The coaxial diffuse reflectance read head of claim 1 further comprising a reference light detector for receiving a second portion of said collimated light, said second portion of collimated light passing through said beam splitter.

4. The coaxial diffuse reflectance read head of claim 1 wherein said beam splitter has outer edges beveled to reduce loss of diffuse light received from said optical fiber.

5. The coaxial diffuse reflectance read head of claim 4 wherein said beam splitter has outer edges beveled at a 45°

angle.

6. The coaxial diffuse reflectance read head of claim 1 wherein said optical fiber has a diameter substantially equal to said test area.

7. The coaxial diffuse reflectance read head of claim 6 wherein said optical fiber and said test area have a diameters in the range of from about 0.25 to about 3 mm.

8. The coaxial diffuse reflectance read head of claim 7 wherein said optical fiber has a diameter of about 1 mm.

9. The coaxial diffuse reflectance read head of claim 1 wherein said spatial filter contains an opaque area disposed to block specular light passing through said beam splitter.

10. The coaxial diffuse reflectance read head of claim 9 wherein said opaque area is larger than said optical fiber.

11. The coaxial diffuse reflectance read head of claim 1 wherein said optical fiber has a reagent coating on said second end of the fiber and said fiber is positioned to contact a sample on said test area.

12. The coaxial diffuse reflectance read head of claim 11 wherein said optical fiber is disposable.

13. The coaxial diffuse reflectance read head of claim 1 wherein said optical fiber is positioned to closely approach said test area and to minimize loss of said collimated light.

14. The coaxial diffuse reflectance read head of claim 12 wherein said optical fiber is positioned about 0.25 to 2 mm from said test area.

15. The coaxial diffuse reflectance read head of claim 13 wherein said test area contains a test strip containing reagents for reacting with a sample in said test strip.

16. The coaxial diffuse reflectance read head of claim 1 wherein said collimated light source comprises an LED.

17. The coaxial diffuse reflectance read head of claim 1 wherein said collimated light source is a halogen lamp.

18. The coaxial diffuse reflectance read head of claim 1 wherein said beam splitter is a 50/50 beam splitter.

19. The coaxial diffuse reflectance read head of claim 1 wherein said optical fiber has a diameter larger than the diameter of said collimated light.

20. A method of measuring an analyte in a biological sample the method comprising the acts of:

(a) providing collimated light from a light source;

(b) directing said collimated light with a beam splitter into a first end of an optical fiber, a second end of said optical fiber being in contact with a test area or closely approaching said test area;

(c) directing diffuse and specular light returned from said test area via said optical fiber to said beam splitter, said specular reflected light passing through said beam splitter and contacting a spatial filter, thereby preventing said specular light from being detected, said diffuse reflected light passing around said spatial filter and contacting a light detector; and

(d) measuring the diffuse reflected light with said light detector and correlating the measured diffuse reflected light with the amount of an analyte in said biological sample.

21. The method of claim 20 wherein said optical fiber has a diameter substantially equal to said test area.

22. The method of claim 20 wherein said beam splitter has outer edges beveled to reduce loss of diffuse light received from said optical fiber.

23. The method of claim 20 wherein said optical fiber has a reagent coating on said second end of said optical fiber and said fiber is positioned to contact said sample on said test area.

24. The method of claim 20 wherein said optical fiber is positioned to closely approach said test area and to minimize loss of said collimated light.

25. The method of claim 24 wherein said optical fiber supplies collimated light to a test strip in said test area.

26. The method of claim 20 wherein said test area is monitored for an initial change in diffuse light, said change in diffuse light being used as an indicator for the beginning of a reaction with said analyte in a said test area.

27. The method of claim 20 wherein said analyte is glucose and said biological sample is whole blood.