Apparatus, sample cuvette and method for optical measurements

• US 6,943,883 B2
• Filed: 07/18/2002
• Issued: 09/13/2005
• Est. Priority Date: 01/18/2000
• Status: Expired due to Fees

• Current Assignee: Radiometer Medical ApS (Danaher Corporation)
• Original Assignee: Radiometer Medical ApS (Danaher Corporation)
• Inventors: Fodgaard, Henrik
• Primary Examiner(s): Smith, Zandra V.
• Application Number:
  US10/198,400
• Publication Number:
  US 20020176068A1
• Time in Patent Office: 1,153 Days
• Field of Search: 356/39, 356/440, 356436-437, 356/246, 422/58, 422/68.1, 422/105, 436/66, 436/70, 436165-166
• US Class Current: 356/436
• CPC Class Codes: G01N 2021/0346 Capillary cells; Microcells
• CPC Class Codes: G01N 2021/513 Cuvettes for scattering measurements
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/51 inside a container, e.g. in an ampoule G01N21/53 takes precedence

Abstract

An apparatus, a sample cuvette and a method for optical measurements on samples which show variable levels of scattering are provided. The apparatus, sample cuvette and method may be used for optical measurements on biological, physiological and chemical samples, however, are especially applicable for optical measurements on whole blood.

Claims

1. An apparatus for optical measurements on light scattering samples comprising at least one light emission means (12), a sample cuvette (15) with a sample chamber and a detecting means (19),

the apparatus being characterised in that it comprises

an absorption filter (18) which is positioned in the light path between the sample cuvette (15) and the detecting means (19), said absorption filter (18) has a center and a periphery and an absorbance which decreases from the center towards the periphery.

2. An apparatus according to claim 1 for optical measurements of the concentration of any of hemoglobin, oxyhemoglobin, deoxyhemoglobin, methemoglobin, carboxyhemoglobin, sulfhemoglobin, bilirubin and/or diagnostic dyes.

3. An apparatus according to any of the claims 1, in which the absorption filter (18) has annular zones (21-25) defined by a range of scattering angles α

′

_n, each zone having an absorbance F(α

′

_n), so that for any two annular zones of the absorption filter (18), defined by the ranges of scattering angles α

′

_s and α

′

_t, the corresponding absorbances being F(α

′

_s) and F(α

′

_t), F(α

′

_s)>

F(α

′

_t) in case α

′

_t is more peripheric than α

′

_s.

4. An apparatus according to 3, in which the detector (19) has a detector angular sensitivity defining a detector angular absorbance DAA(α

′

_n) in the scattering angle range α

′

_n and in which the sample has an effective optical pathlength defining a pathlength angular absorbance PAA(α

′

_n) in the scattering angle range α

′

_n and in which the absorption filter (18) has an absorbance F(α

′

_n)=ABS_max−

(DAA(α

′

_n)+PAA(α

′

_n)), where ABS_max is the maximum absorbance of the absorption filter.

5. An apparatus according to claim 4, in which the maximum filter absorbance ABS_max is equal to DAA(α

′

_max)+PAA(α

′

_max), where DAA(α

′

_max) is the detector angular absorbance in the outer angular range (α

′

_max) and where PAA(α

′

_max) is the pathlength angular absorbance in the outer angular range (α

′

_max).

6. An apparatus according to any of the preceding claim 3, in which the absorption filter (18) has an absorbance in the scattering angle ranges 0°

-20°

, 20°

-40°

, 40°

-50°

, 50°

-60° and

>

60°

, respectively, of F(0°

-20°

)=0.40-0.90F,(20°

-40°

)=0.25-0.60F, (40°

-50°

)=0.10-0.40, F(50°

-60°

)=0.05-0.25 and F(>

60°

)=0.00 and where further, for any two ranges α

′

_s and α

′

_t, F(α

′

_s)>

F(α

′

_t) in case α

′

_t is more peripheric than α

′

_s.

7. An apparatus according to claim 3, in which each annular zone (21-25) of the absorption filter (18) displays uniform absorbance.

8. An apparatus according to claim 4, in which at least one annular zone (31-35) of the absorption filter (18) displays at least one subzone of uniform maximum absorbance ABS_max (31a-34a) and at least one subzone of no absorbance (32b-35b).

9. An apparatus according to claim 1, in which the detector (19) has a detector angular sensitivity defining a detector angular absorbance DAA(α

) at a scattering angle α and

in which the sample has an effective optical pathlength defining a pathlength angular absorbance PAA(α

) at the scattering angle α

, in which the absorption filter (18) has an absorbance described by any mathematical function G(α

)=ABS_max−

(DAA(α

)+PAA(α

)), where ABS_max is the maximum absorbance of the absorption filter.

10. An apparatus according to claim 1, in which the absorption filter (18) consists of a foil of polymer material onto which a light absorbing chemical compound has been deposited.

14. An apparatus according to claim 1, in which the filter is provided as a separate component.

15. An apparatus according to claim 1, in which the filter is provided as an integrated part of the sample cuvette (15) or an integrated part of the detector (19).

16. An apparatus according to claim 15 in which the sample cuvette (15) has a light exit window (16) and in which the filter is printed onto the light exit window (16).

17. An apparatus according to claim 15, in which the filter is provided as an integrated part of the sample cuvette (15) and where the sample cuvette (15) with the filter is a disposable unit for use in one or a few measurements only.

18. An apparatus according to claim 1, in which the detecting means (19) has a detection range, defined by the scattering angle α

, of at least 0-50°

.

19. An apparatus according to claim 1, in which the distance between the center of the sample chamber and the detecting means (19) is in the range 0.2-1.5 millimeter.

20. An apparatus according to claim 1, in which the detecting area of the detecting means (19) is at least 25 square millimeter.

21. An apparatus according to claim 1, in which the apparatus comprises one or more optical couplings, which are positioned between the sample cuvette (15) and the filter (18) and/or between the filter (18) and the detecting means (19).

22. An apparatus according to claim 21, in which the thickness of the one or more optical couplings is in the range 1-100 μ

m.

23. An apparatus according to claim 21, in which the one or more optical couplings are made of glycerols, silicones or acrylates.

24. An apparatus according to claim 1, in which an aperture is placed between the light source (12) and the sample cuvette (15).

25. An apparatus according to claim 24, in which the aperture has an area not larger than 1 square millimeter.

11. An apparatus for optical measurements on light scattering samples comprising at least one light emission means (12), a sample cuvette (15) with a sample chamber and a detecting means (19),

the apparatus further being characterised in that it comprises

an interference filter which is positioned in the light path between the sample cuvette (15) and the detecting means (19), and which is selected from the groups of band pass filters and long wavelength pass filters having a center wavelength and a cut-off wavelength, respectively, which are longer than the wavelength of the light from the light emission means.

12. An apparatus according to claim 11 for optical measurements of the concentration of any of hemoglobin, oxyhemoglobin, deoxyhemoglobin, methemoglobin, carboxyhemoglobin, sulfhemoglobin, bilirubin and/or diagnostic dyes.

13. An apparatus according to claim 11, in which the interference filter is a band pass filter of a center wavelength in the range 505-630 nm, or is a long wavelength pass filter of a cut-off wavelength in the range 505-630 nm.

26. A sample cuvette (15) for optical measurements on light scattering samples comprising a sample chamber and light entry and light exit windows (16), respectively, on the walls defining the sample chamber,

the sample cuvette being characterised in that it comprises

an absorption filter (18) as an integrated part of the sample cuvette (15), positioned on or into the exit window (16) of the sample cuvette (15), said absorption filter (18) has a center and a periphery and an absorbance which decreases from the center towards the periphery.

27. A sample cuvette (15) according to claim 26, in which the absorption filter (18) has annular zones (21-25) defined by a range of scattering angles α

′

_n, each zone having an absorbance F(α

′

_n), so that for any two annular zones of the absorption filter (18), defined by the ranges of scattering angles α

′

_s and α

′

_t, the corresponding absorbances being F(α

′

_s) and F(α

′

_t), F(α

′

_s)>

F(α

′

_t) in case α

′

_t is more peripheric than α

′

_s.

28. A sample cuvette according to claim 26, in which the absorption filter (18) has an absorbance in the scattering angle ranges 0°

-20°

, 20°

-40°

, 40°

-50°

, 50°

-60° and

>

60°

, respectively, of F(0°

-20°

)=0.40-0.90, F(20°

-40°

)=0.25-0.60, F(40°

-50°

)=0.10-0.40, F(50°

-60°

)=0.05-0.25 and F(>

60°

)=0.00 and where further, for any two ranges α

′

_s and α

′

_t, F(α

′

_s)>

F(α

′

_t) in case α

′

_t is more peripheric than α

′

_s.

29. A sample cuvette (15) according to claim 27, in which each annular zone (21-25) of the absorption filter (18) displays uniform absorbance.

30. A sample cuvette (15) according to claim 27, in which at feast one annular zone (31-35) of the absorption filter (18) displays at least one subzone of uniform maximum absorbance ABS_max (31a-34a) and at least one subzone of no absorbance (32b-35b).

31. A sample cuvette (15) according to claim 26, in which the absorption filter (18) consists of a foil of polymer material onto which a light absorbing chemical compound has been deposited.

34. A sample cuvette (15) according to claim 26, in which the filter is printed onto the light exit window (16) of the sample cuvette (15).

35. A sample cuvette (15) according to claim 26, in which the sample cuvette (15) is a disposable unit for use in one or a few measurements only.

32. A sample cuvette (15) for optical measurements on light scattering samples comprising a sample chamber and light entry and light exit windows (16), respectively, on the walls defining the sample chamber,

the sample cuvette being characterised in that it comprises

an interference filter as an integrated part of the sample cuvette (15), positioned on or into the exit window (16) of the sample cuvette (15) and which is selected from the groups of band pass filters and long wavelength pass filters.

33. A sample cuvette (15) according to claim 32, in which the interference filter is a band pass filter of a center wavelength in the range 505-630 nm, or is a long wavelength pass filter of a cut-off wavelength in the range 505-630 nm.

36. A method for optical measurements on light scattering samples, in which

(1) light of one or more wavelengths from at least one light emission means (12) is passed through the sample, and

(2) scattered light is detected by a detecting means (19),

which method employs an apparatus comprising at least one light emission means (12), a sample cuvette (15) with a sample chamber, the dectecting means (19), and an absorption filter (18) which is positioned in the light path between the sample cuvette (15) and the detecting means (19), said absorption filter (18) having a center and a periphery and an absorbance which decreases from the center towards the periphery.

37. A method for optical measurements according to claim 36, in which light of only one wavelength is used.

38. A method for optical measurements according to claim 36, in which light of at least 2 wavelengths is used.

39. A method for optical measurements according to claim 36 for the determination of the concentration of any hemoglobin, oxyhemoglobin, deoxyhemoglobin, methemoglobin, carboxyhemoglobin sulfhemoglobin, bilirubin and/or diagnostic dyes.

40. A method for optical measurements according to claim 36, in which measurements are preformed on non-flowing samples situated in the sample chamber.