Non-invasive sensor capable of determining optical parameters in a sample having multiple layers

• US 6,630,673 B2
• Filed: 12/21/2001
• Issued: 10/07/2003
• Est. Priority Date: 11/23/1998
• Status: Expired due to Term

• Current Assignee: Abbott Laboratories
• Original Assignee: Abbott Laboratories
• Inventors: Yeh, Shu-Jen, Bolt, Reneʼ Alexander, Kanger, Johannes Sake, de Mul, Frits Frans Maria, Khalil, Omar S., Hanna, Charles F., Wu, Xiaomao
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US10/036,826
• Publication Number:
  US 20020084417A1
• Time in Patent Office: 655 Days
• Field of Search: 250/339.11, 250/341.8, 600/310, 600/322, 600/323, 356/432
• US Class Current: 250/341.8
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

Apparatus and method for non-invasively measuring at least one optical parameter of a sample, particularly a sample of tissue that comprises a plurality of layers. The at least one parameter can be used to determine the presence or concentration of an analyte of interest in the sample of tissue. The apparatus and method of the present invention (1) measure light that is substantially reflected, scattered, absorbed, or emitted from a shallower layer of the sample of tissue, (2) measure light that is substantially reflected, scattered, absorbed, or emitted from a deeper layer of the sample of tissue, (3) determine at least one optical parameter for each of these layers, and (4) account for the effect of the shallower layer on the at least one optical parameter of the deeper layer. Specifying the sampling depth allows determinations of the optical properties of a specific layer of the sample of the tissue, e.g., dermis, and decreases interference from other layers, e.g., stratum corneum and epidermis, in these determinations.

Claims

1. An apparatus for determining the concentration of an analyte in a sample, said apparatus comprising:

a) at least one source of light, said at least one source of light adapted to introduce light at a single light introduction site on a surface of said sample;

b) at least two groups of light collecting elements, each of said groups of light collecting elements comprising at least two light collecting elements, each of said groups of light collecting elements located at a different distance from said light introduction site on said surface of said sample, each of said different distances corresponding to a different depth in said sample, wherein said light collecting elements comprise optical fibers, said optical fibers being arranged in a hexagonal close-packed structure;

c) at least one detector for measuring light collected by said light collecting elements; and

d) a signal processor to determine said concentration of said analyte of said sample.

2. The apparatus of claim 1, wherein said light collecting elements are disposed in a non-reflecting housing.

3. The apparatus of claim 1, wherein some of said fibers in said close-packed structure direct re-emitted light to said at least one detector and other of said fibers in said close-packed structure direct re-emitted light to a light trap.

4. The apparatus of claim 1, wherein the distance of said single light introduction site on said surface of said sample to said groups of light collecting elements and the wavelengths of said source of light are selected to limit the depth of penetration of light in said sample to a depth wherein the temperature is being controlled.

5. The apparatus of claim 1, wherein the distance between said single light introduction site on said surface of said sample and any light collecting element is no more than 6 mm.

6. An apparatus for determining the concentration of an analyte in a sample, said apparatus comprising:

a) at least one source of light for introducing light to defined areas on a surface of said sample;

b) at least two groups of illuminating elements, each of said groups of illuminating elements comprising at least two illuminating elements, each of said groups of illuminating elements located at a different distance from a single light collection site on said surface of said sample, each of said distances corresponding to a different depth in said sample, wherein said illuminating elements comprise optical fibers, said optical fibers being arranged in a hexagonal close-packed structure;

c) at least one detector, said at least one detector adapted to determine the intensity of light collected at said single light collection site; and

d) a signal processor to determine said concentration of said analyte of said sample.

7. The apparatus of claim 6, wherein said illuminating elements are disposed in a non-reflecting housing.

8. The apparatus of claim 6, wherein the distance of the illuminating elements to said single light collection site on said surface of said sample and the wavelengths of said at least one source of light are selected to limit the depth of penetration of light in the sample to a depth wherein the temperature is being controlled.

9. The apparatus of claim 6, wherein the distance between said single light collection site and any illuminating element on said surface of said sample is no more than 6 mm.