Noninvasive glucose sensor

• US 20050256384A1
• Filed: 05/11/2004
• Published: 11/17/2005
• Est. Priority Date: 05/11/2004
• Status: Active Grant

• Current Assignee: Nostix, LLC (Teleflex Incorporated)
• Original Assignee: Nostix, LLC (Teleflex Incorporated)
• Inventors: Repine, John E., Henry, Charles W., Nelson, Peter E., Zellers, R. Dale, Walker, Stephen D.
• Granted Patent: US 7,251,516 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• 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: A61K 31/405 Indole-alkanecarboxylic acids; Derivatives thereof, e.g. tryptophan, indomethacin

Abstract

Glucose concentration is noninvasively measured by measuring a plurality of absorption values using at least one emitter operating at a corresponding plurality of emission wavelengths through a common optical sample volume and deriving glucose concentration from the absorption measurement values.

Claims

1. A noninvasive glucose sensor comprising:

at least one emitter;

at least one photo detector configured to detect emissions from the emitter;

a controller coupled to the at least one emitter adapted to control infrared emission by the emitter including shifting of emitter wavelength to measure absorption at a plurality of wavelengths through a common optical sample volume, and deriving a glucose concentration measurement from measured absorption values.

2. The sensor according to claim 1 further comprising:

the controller having a capability to increase or decrease drive current to the at least one emitter to modify emitter temperature resulting in a shift in emitter wavelength, the glucose concentration in the common optical sample volume being determined from absorption measurements acquired at wavelengths differing by the wavelength shift.

3. The sensor according to claim 1 further comprising:

the controller having a capability to increase or decrease drive current to the at least one emitter to modify emitter temperature resulting in a shift of 1-2 nm in emitter wavelength, the glucose concentration in the common optical sample volume being determined from absorption measurements acquired at wavelengths differing by the 1-2 nm wavelength shift.

4. The sensor according to claim 1 further comprising:

an interface coupled to the controller that exhibits a condition based on the glucose concentration measurement.

5. The sensor according to claim 1 further comprising:

a visual display coupled to the controller capable of presenting a visible display of the condition based on the glucose concentration measurement.

6. The sensor according to claim 1 further comprising:

an annunciator coupled to the controller capable of generating a signal indicative of the condition based on the glucose concentration measurement, the signal being selected from among a group consisting of audible, visual, vibration, and electronic signals, or a combination thereof.

7. The sensor according to claim 1 further comprising:

a housing enclosing the at least one emitter, the at least one photo detector, and the controller, and having apertures for insertion of the emitter and photo detector enabling contact exterior to the housing; and

a band coupled to the housing and capable of mounting the housing to a measurement body part.

8. The sensor according to claim 1 wherein:

the at least one emitter generates narrowband light that is shifted under control of the controller to a plurality of emitter wavelengths.

9. The sensor according to claim 1 wherein:

the at least one emitter generates narrowband light in a range from 760-1065 nm that is shifted in a range of ones to tens of nanometers under control of the controller to a plurality of emitter wavelengths.

10. The sensor according to claim 1 wherein:

the controller controls the at least one emitter to shift emitter wavelength by 1-2 nanometers between measurement samples for one or more wavelengths selected from a group of approximate wavelengths comprising 1060 nm, 980 nm, 850 nm, 825 nm, 800 nm, 780 nm, and 765 nm.

11. The sensor according to claim 1 wherein:

the controller controls the at least one emitter to shift emitter wavelength by at least one nanometer between two measurement samples in a range from ±

5 nm from a selected center wavelength, resulting in two independent equations with two unknown concentrations of analytes glucose (G) and water (W) the equations being of the form;

A<sub>λ

1</sub>=ε

<sub>λ

1</sub>^GG+ε

<sub>λ

1</sub>^WW
A<sub>λ

2</sub>=ε

<sub>λ

2</sub>^GG+ε

<sub>λ

2</sub>^WW

 

where A is absorption and ε

is absorption factor of an analyte at a wavelength, the controller solving the equations for glucose concentration (G) and water concentration (W) using equations of the form;

$G=\frac{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W<br><br>A_{\mathrm{\lambda <br><br>1}}-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W<br><br>A_{\mathrm{\lambda <br><br>2}}}{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G}$$W=\frac{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>A_{\mathrm{\lambda <br><br>2}}-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G<br><br>A_{\mathrm{\lambda <br><br>1}}}{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W}.$

12. The sensor according to claim 1 further comprising:

an alarm coupled to the controller that is annunciated automatically on one or more preselected conditions selected from among a group of conditions comprising;

(1) glucose levels decreasing below a predetermined threshold, (2) glucose levels increasing above a predetermined threshold, (3) water levels decreasing below a predetermined threshold, and (4) water levels increasing above a predetermined threshold.

13. The sensor according to claim 1 wherein:

the at least one emitter is selected from among vertical cavity surface emitting laser (VCSEL) emitters and semiconductor laser diode emitters.

14. The sensor according to claim 1 wherein:

the controller is capable of generating an electronic signal indicative of a condition based on the glucose concentration measurement, the signal for actuating a syringe or pump to inject insulation.

15. A noninvasive glucose sensor comprising:

a plurality of emitters capable of generating multiple-wavelength emissions at multiple different emitter center wavelengths;

at least one photo detector configured to detect emissions from the emitters;

a controller coupled to the plurality of emitters and adapted to control signal acquisition by the emitters including activating ones of the plurality of emitters operating at multiple wavelengths to measure absorption at corresponding multiple wavelengths through a common optical sample volume, and deriving a glucose concentration measurement from the absorption measurement values.

16. The sensor according to claim 15 further comprising:

the controller having a capability to increase or decrease drive current to the at least one emitter to modify emitter temperature resulting in a shift in emitter wavelength, the glucose concentration in the common optical sample volume being determined from absorption measurements acquired at wavelengths differing by the wavelength shift.

17. The sensor according to claim 15 further comprising:

an interface coupled to the controller that exhibits a condition based on the glucose concentration measurement.

18. The sensor according to claim 15 further comprising:

a visual display coupled to the controller capable of presenting a visible display of the condition based on the glucose concentration measurement.

19. The sensor according to claim 15 further comprising:

an annunciator coupled to the controller capable of generating an audible signal indicative of the condition based on the glucose concentration measurement.

20. The sensor according to claim 15 further comprising:

a housing enclosing the plurality of emitters, the at least one photo detector, and the controller, and having apertures for insertion of the photo detectors enabling contact exterior to the housing; and

a band coupled to the housing and capable of mounting the housing to a measurement body part.

21. The sensor according to claim 15 wherein:

the emitters generate narrowband light at the multiple emitter wavelengths.

22. The sensor according to claim 15 wherein:

the plurality of emitters generate narrowband light in a range from 760-1065 m including different wavelengths that vary in a range of ones to tens of nanometers.

23. The sensor according to claim 15 wherein:

the controller controls the at least one emitter to shift emitter wavelength by 1-2 nanometers between measurement samples for one or more wavelengths selected from a group of approximate wavelengths comprising 1060 nm, 980 nm, 850 nm, 825 nm, 800 nm, 780 nm, and 765 nm.

24. The sensor according to claim 15 wherein:

the controller controls the emitters sequentially to shift emitter wavelength by at least one nanometer between two measurement samples in a range from ±

5 nm from a selected center wavelength, resulting in two independent equations with two unknown concentrations of analytes glucose (G) and water (W) the equations being of the form;

A<sub>λ

1</sub>=ε

<sub>λ

1</sub>^GG(CenterWavelength)+ε

<sub>λ

1</sub>^WW(CenterWavelength)
A<sub>λ

2</sub>=ε

<sub>λ

2</sub>^GG(CenterWavelength)+ε

<sub>λ

2</sub>^WW(CenterWavelength)

 

where A is absorption and ε

is absorption factor of an analyte at a wavelength, the controller solving the equations for glucose concentration (G (CenterWavelength)) and water concentration (W (CenterWavelength)) using equations of the form;

$G<br><br>\left(\mathrm{CenterWavelength}\right)=\frac{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W<br><br>A_{\mathrm{\lambda <br><br>1}}-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W<br><br>A_{\mathrm{\lambda <br><br>2}}}{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G}$$W<br><br>\left(\mathrm{CenterWavelength}\right)=\frac{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>A_{\mathrm{\lambda <br><br>2}}-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G<br><br>A_{\mathrm{\lambda <br><br>1}}}{{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^W-{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>2}}^G<br><br>{\mathrm{\varepsilon <br><br>}}_{\mathrm{\lambda <br><br>1}}^W},$

 

glucose (G) and water (W) concentrations being calculated using equations of the form;

$G=\frac{G<br><br>\left(\mathrm{CenterWavelength1}\right)+G(\mathrm{CenterWavelength2}+\mathrm{\dots <br><br>}}{n}$$W=\frac{W<br><br>\left(\mathrm{CenterWavelength1}\right)+W(\mathrm{CenterWavelength2}+\mathrm{\dots <br><br>}}{n}$

 

where n is the number of emitters.

25. The sensor according to claim 15 further comprising:

an alarm coupled to the controller that is annunciated automatically on one or more preselected conditions selected from among a group of conditions comprising;

(1) glucose levels decreasing below a predetermined threshold, (2) glucose levels increasing above a predetermined threshold, (3) water levels decreasing below a predetermined threshold, and (4) water levels increasing above a predetermined threshold.

26. The sensor according to claim 15 wherein:

the at least one emitter is selected from among vertical cavity surface emitting laser (VCSEL) emitters and semiconductor laser diode emitters.

27. The sensor according to claim 15 wherein:

the controller is capable of generating an electronic signal indicative of a condition based on the glucose concentration measurement, the signal for actuating a syringe or pump to inject insulation.

28. A method of noninvasively measuring glucose concentration comprising:

measuring a plurality of absorption values using at least one emitter operating at a corresponding plurality of emission wavelengths through a common optical sample volume; and

deriving glucose concentration from the absorption measurement values.

29. The method according to claim 28 further comprising:

increasing or decreasing drive current to the at least one emitter to modify emitter temperature resulting in a shift in emitter wavelength; and

determining glucose concentration in the common optical sample volume from absorption measurements acquired at wavelengths differing by the wavelength shift.

30. An article of manufacture comprising:

a controller usable medium having a computable readable program code embodied therein for noninvasively measuring glucose concentration, the computable readable program code further comprising;

a computable readable program code capable of causing the controller to measure a plurality of absorption values using at least one emitter operating at a corresponding plurality of emission wavelengths through a common optical sample volume; and

a computable readable program code capable of causing the controller to derive glucose concentration from the absorption measurement values.

31. The article of manufacture according to claim 30 further comprising:

a computable readable program code capable of causing the processor to increase or decrease drive current to the at least one emitter to modify emitter temperature resulting in a shift in emitter wavelength; and

a computable readable program code capable of causing the processor to determine glucose concentration in the common optical sample volume from absorption measurements acquired at wavelengths differing by the wavelength shift.