Devices and methods for calibration of a thermal gradient spectrometer

• US 6,196,046 B1
• Filed: 08/25/1999
• Issued: 03/06/2001
• Est. Priority Date: 08/25/1999
• Status: Expired due to Fees

• Current Assignee: OptiScan Biomedical Corporation
• Original Assignee: OptiScan Biomedical Corporation
• Inventors: Kramer, Charles E., Braig, James R., Sterling, Bernhard B., Goldberger, Daniel S., Azizi, Kamrava, Godfrey, Joan C., Correia, David J.
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US09/382,273
• Time in Patent Office: 559 Days
• Field of Search: 73/10.1, 73/10.3, 250/252.1, 600/316, 356/243
• US Class Current: 73/1.03
• CPC Class Codes: A61B 2560/0233 Optical standards
• CPC Class Codes: A61B 2560/0271 using a remote monitoring unit
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes

Abstract

A calibration standard for calibrating a thermal gradient spectrometer. The calibration standard is a structure having a particular glucose concentration which a thermal gradient spectrometer reads for determining whether the spectrometer is in calibration. The structure of the calibration standard properly mimics the physiology of human tissue. A number of such standards, each containing a different concentration of glucose are provided in kit form with a thermal gradient spectrometer for use in calibrating the spectrometer. The spectrometer is provided with a display and internal circuitry for performing self-calibrating adjustments and a communications port for electronically coupling to a remote computer and database for supplying external calibration commands to said spectrometer.

Claims

1. A calibration standard apparatus for use in calibrating a thermal gradient spectrometer, said apparatus comprising:

a layered polymeric standard having a structure that simulates human skin, said structure being flat and having a shape for being removably positioned within a calibration port of said spectrometer, said structure including a first layered structural portion that simulates the human stratum corneum and a second layered structural portion that simulates the human epidermis, said structure being impregnated with an amount of glucose, said amount of glucose being representative of a blood-sugar level value of a diabetic person, said value being used for calibrating said spectrometer.

2. A calibration standard apparatus as described in claim 1, wherein said apparatus further comprises:

a portion having embedded coded information.

3. A calibration standard apparatus as described in claim 2, wherein:

said embedded coded information comprises a bar code portion, a resistor code, a semiconductor memory device, and a reserved space for future coded features.

4. A calibration standard apparatus as described in claim 2, wherein said apparatus further comprises:

a handling portion.

5. A calibration standard apparatus as described in claim 4, wherein

said embedded coded information comprises a bar code portion, a resistor code, a semiconductor memory device, and a reserved space for future coded features.

6. A calibration standard apparatus as described in claim 1, wherein

said shape comprises a rectangular solid, and wherein said first layered structural portion comprises a side intended for being placed in contact with an optical window of said spectrometer and being exposed to the spectrometer'"'"'s thermal mass to effect thermal gradients on said standard.

7. A calibration standard apparatus as described in claim 1, wherein

said shape comprises a cylindrical body and wherein said first layered structural portion comprises a side intended for being placed in contact with an optical window of said spectrometer and being exposed to the spectrometer'"'"'s thermal mass to effect thermal gradients on said standard.

8. A calibration standard apparatus as described in claim 1, wherein

said blood-sugar level value comprises a concentration of glucose selected from a group of glucose concentration values comprising 0%, 50, 100, 500, 1000 mg/dl of glucose.

9. A calibration standard apparatus as described in claim 8, wherein

a group of said calibration said standard apparatus are provided, said group of standards comprising respective calibration standards having 0%, 50, 100, 500, 1000 mg/dl of glucose, said group of standards being packaged in a hermetic container and treated to prolong shelf life and to retard microbial growth, said container being provided with identifying information corresponding to said packaged group of standards.

10. A calibration standard apparatus as described in claim 9, wherein

said group of standards are provided as sterile calibration standards.

11. A calibration standard apparatus as described in claim 1, wherein said first layered structural portion comprises the following properties:

a thickness=50 μ

m+/−

20 μ

m;

a moisture content less than 20%;

a no spectral features in the infrared band from 3-12 μ

m;

a thermal conductivity in the range of 0.21 to 0.26 watts/meter-°

C., and

a specific heat in the range of 3578 to 3600 Joules/Kg-°

C.

12. A calibration standard apparatus as described in claim 1, wherein said first layered structural portion comprises the following properties:

a thickness=300 μ

m+/−

50 μ

m;

a moisture content=80% +/−

10%;

a glucose spectral features at 9.6 μ

m;

a no other spectral features in the infrared band from 3-12 μ

m;

a thermal impedance in the range of 0.3 to 0.52 watts/meter-°

C., and

a specific heat in the range of 3200 to 3400 Joules/Kg-°

C.

13. A diabetic blood-sugar level testing kit, comprising:

a non-invasive thermal gradient spectrometer; and

at least one calibration standard apparatus for use in calibrating said non-invasive thermal gradient spectrometer, said calibration standard apparatus comprising;

a layered polymeric standard having a structure that simulates human skin, said structure being flat and having a shape for being removably positioned within a calibration port of said spectrometer, said structure including a first layered structural portion that simulates the human stratum corneum and a second layered structured portion that simulates the human epidermis, said structure being impregnated with an amount of glucose, said amount of glucose being representative of a blood-sugar level value of a diabetic person, said value being used for calibrating said spectrometer.

14. A diabetic blood-sugar level testing kit as described in claim 13, wherein:

said non-invasive thermal gradient spectrometer comprises a display portion having a plurality of window areas for displaying information about operational activity of said spectrometer, said activity including displaying standard concentration value, displaying actual concentration readout, and displaying message of calibration results and suggested action.

15. A diabetic blood-sugar level testing kit as described in claim 14, wherein:

said spectrometer comprises a remote network communication port and internal circuitry coupled to said remote network communication port for effecting remote calibration of said spectrometer by a remote computer and for accessing a remote database comprising patient information including treatment options in accordance with a patients history of blood-sugar readings.

16. A method of calibrating a thermal gradient spectrometer, said method comprising the steps of:

a) providing a diabetic blood-sugar level testing kit, said kit comprising;

a non-invasive thermal gradient spectrometer, said non-invasive thermal gradient spectrometer comprising;

a display portion having a plurality of window areas for displaying information about operational activity of said spectrometer, said activity including displaying standard concentration value, displaying actual concentration readout, and displaying message of calibration results and suggested action; and

a remote network communication port and internal circuitry coupled to said remote network communication port for effecting remote calibration of said spectrometer by a remote computer and for accessing a remote database comprising patient information including treatment options in accordance with a patient'"'"'s history of blood-sugar readings; and

at least one calibration standard apparatus for use in calibrating said non-invasive thermal gradient spectrometer, said calibration standard apparatus comprising;

a layered polymeric standard having a structure that simulates human skin, said structure being flat and having a shape for being removably positioned within a calibration port of said spectrometer, said structure including a first layered structural portion that simulates the human stratum corneum and a second layered structural portion that simulates the human epidermis, said structure being impregnated with an amount of glucose, said amount of glucose being representative of a blood-sugar level value of a diabetic person, said value being used for calibrating said spectrometer

(b) placing said spectrometer in a calibration mode;

(c) placing said standard apparatus in said communications port;

(d) exposing said positioned standard in step (c) to thermal gradients from a thermal mass window in said spectrometer;

(e) scanning said standard exposed to said thermal gradient;

(f) determining a glucose concentration of said scanned standard;

(g) comparing said determined glucose concentration against an actual glucose concentration impregnated in said standard;

(h) determining a type of calibration action to be taken; and

(i) displaying results of said calibration taken.

17. A method of calibrating a thermal gradient spectrometer, as described in claim 16, wherein said step (h) comprises a local self-adjusting calibration step.

18. A method of calibrating a thermal gradient spectrometer, as described in claim 16, wherein said step (h) comprises a remote calibrating step.

19. A method of calibrating a thermal gradient spectrometer, as described in claim 16, wherein said step (i) comprises an “

adjustment complete”

message.

20. A method of calibrating a thermal gradient spectrometer, as described in claim 16, wherein said step (i) comprises a “

perform manual adjustments”

message.