Absolute calibration process and device for a tissue modulated raman spectrometer

• US 20050106651A1
• Filed: 11/12/2004
• Published: 05/19/2005
• Est. Priority Date: 11/12/2003
• Status: Active Grant

• Current Assignee: Lightouch Medical, Inc.
• Original Assignee: Lightouch Medical, Inc.
• Inventors: Chaiken, Joseph, Hagrman, Pamela J., Chawan, Dhyaneshwar Bhujangarao, Hagrman, Douglas
• Granted Patent: US 7,664,605 B2
• Time in Patent Office: Days
• US Class Current: 435/14
• CPC Class Codes: G01N 21/278 Constitution of standards
• CPC Class Codes: G01N 21/4785 Standardising light scatter apparatus; Standards therefor
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

A calibrator suitable for calibrating a noninvasive analyte detector, such as a Raman spectroscopy device, allows the user of the detection device to establish standard measurements of the analyte to be detected, thereby providing assurance that appropriate analyte measurements are obtained at the time of sampling. The calibrator is simple to use, making it suitable for home use by individuals regardless of medical or technical skill level. In particular, the calibrator can be used with a noninvasive glucose detection system, such as for monitoring of blood glucose levels in diabetics. For use with noninvasive detectors designed for obtaining measurements from a subject'"'"'s fingertip, the calibrator can be formed into a shape that reasonably mimics a fingertip in size, texture and/or spectral properties.

Claims

1. A calibrator comprising:

a body comprising a standard quantity of an analyte;

wherein the calibrator scatters near infrared radiation in the Mie limit, and

wherein the calibrator is adapted to be apposed to an aperture of a spectrometer.

2. The calibrator of claim 1, wherein the analyte is glucose.

3. The calibrator of claim 1, wherein the body further comprises a gelatinous material comprising a protein and a carbohydrate.

4. The calibrator of claim 3, wherein the gelatinous material further comprises a preservative.

5. The calibrator of claim 1, wherein the body further comprises a metal alkoxide derived gel.

6. The calibrator of claim 5, further comprising a coating applied to the surface of the body, wherein the coating comprises a sufficiently scattering medium to cause the calibrator to scatter near infrared radiation in the Mie limit.

7. The calibrator of claim 1, further comprising an absorbing layer applied to a sufficient portion of the surface of the body to absorb incident radiation passing through the body from an aperture of a spectrometer.

8. The calibrator of claim 7, wherein the absorbing layer is between about 10 and about 100 microns thick.

9. The calibrator of claim 7, wherein the absorbing layer comprises a fluorescent material or a non-emissive material.

10. The calibrator of claim 1, wherein the surface is modified to provide a detectable indication when it is registered with the aperture of a spectrometer.

11. The calibrator of claim 10, wherein the surface modification comprises bumps, ridges or recesses, and wherein the detectable indication is a resistance to movement upon registry with the aperture.

17. A method of calibrating a spectrometer, the method comprising:

(a) positioning the calibrator of claim 1 in apposition to an aperture of the spectrometer; and

(b) adjusting the spectrometer to identify the standard quantity of the analyte present in the calibrator.

12. A method of producing a calibrator for use with a spectrometer, the method comprising:

(a) selecting analyte particles that are less than about 5 microns in size;

(b) coating the analyte particles selected in step (a) with a fatty acid;

(c) suspending the coated analyte particles in a gelatinous material comprising protein and carbohydrate;

wherein the calibrator scatters near infrared radiation in the Mie limit.

15. A calibrator produced by the method of claim 12.

13. A method of producing a calibrator for use with a spectrometer, the method comprising:

(a) selecting analyte particles that are less than about 5 microns in size;

(b) suspending the selected analyte particles in a sol-gel material comprising a metal alkoxide derived gel to form a body;

(c) applying a coating to the surface of the body, wherein the coating comprises a sufficiently scattering medium to cause the calibrator to scatter near infrared radiation in the Mie limit.

14. The method of claim 13, further comprising:

(d) applying an absorbing layer to a sufficient portion of the surface of the body to absorb incident radiation passing through the body from an aperture of a spectrometer.

16. A calibrator produced by the method of claim 13.