APPARATUS AND METHOD FOR NON-INVASIVE MEASUREMENT OF A SUBSTANCE WITHIN A BODY

• US 20110098542A1
• Filed: 10/28/2009
• Published: 04/28/2011
• Est. Priority Date: 10/28/2009
• Status: Active Grant

• Current Assignee: GlucoVista, Inc.
• Original Assignee: GlucoVista, Inc.
• Inventors: Gerlitz, Yonatan
• Granted Patent: US 8,611,975 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 2560/0252 using ambient temperature
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01N 2021/3188 band-limited
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation

Abstract

A method and apparatus for the noninvasive detection of a concentration of a substance in a body, such as glucose in the human bloodstream is disclosed. The apparatus measures substance concentration by detecting radiation in the far infrared range emitted by the body using an infrared detected in combination with a set of adequate filters. In order to achieve the accuracy required, the radiation values detected by the detector are corrected for the emissions of the system components. The temperature of each system component including the detector temperature and an ambient temperate is determined using temperature sensors attached to the various system components. These temperatures are correlated with a set of predetermined calibration parameters to correct the detector readings.

Claims

1. A system for non-invasive measurement of a substance within a body, comprising:

a detector configured to sense radiation emitted or remitted from a body;

an optical subsystem configured to focus the radiation on a sensitive area of the detector; and

one or more temperature sensors attached to one or more of a plurality of elements of the optical subsystem and to the detector.

2. The system of claim 1, wherein the temperature of one or more of the plurality of optical subsystem elements and the temperature of the detector are matched with a set of predetermined compensation parameters stored in a look-up table for compensating for an effect on the non-invasive measurement of the temperature of each of the one or more of the plurality of elements and the detector, an ambient temperature and a temperature measured at a surface of the body.

3. The system of claim 1, wherein the detector comprises an infrared energy sensor.

4. The system of claim 3, wherein the infrared energy sensor comprises a thermopile detector.

5. The system of claim 1, wherein the optical subsystem comprises one or more mirrors configured to focus the radiation on the sensitive area of the detector.

6. The system of claim 5, wherein the optical subsystem comprises at least two ninety degree (90°

) off-axis parabolic mirrors.

7. The system of claim 5, wherein the optical subsystem comprises at least two mirrors including at least one attenuation filter disposed between the two mirrors for attenuating radiation in a selected wavelength band.

8. The system of claim 5 wherein the optical subsystem two attenuation filters mounted on a moveable frame disposed between the two mirrors.

9. The system of claim 8 wherein the two attenuation filters comprise a first bandpass filter for attenuating radiation in a first selected wavelength band, the first selected wavelength band including at least one wavelength characteristic of the substance and a second bandpass filter for attenuating radiation in a second selected wavelength band, the second selected wavelength band minimizing wavelengths characteristic of the substance.

10. Apparatus for non-invasive measurement of a substance within a body, the apparatus comprising:

a detector for sensing radiation emitted or remitted from a body;

optics configured to focus the radiation on a sensitive area of the detector; and

a baffle attached to and in thermal contact with the detector, the baffle being disposed to at least partially surround a detector sensitive area and configured to minimize the incidence of stray radiation on the detector sensitive area,

wherein an interior surface of the baffle opposite the detector has a high reflectivity and low emissivity, the interior surface of the baffle being formed to minimize the incidence of radiation reflection or multi-reflection on the detector sensitive area.

11. The apparatus of claim 10, further comprising one or more temperature sensors attached to one or more of a plurality of elements of the optics and to the detector.

12. The apparatus of claim 11, wherein the temperature of the one or more of the plurality of optics elements and the temperature of the detector are matched with a set of predetermined compensation parameters stored in a look-up table for compensating for an effect on the non-invasive measurement of the temperature of each of the one or more of the plurality of optics elements and the detector, an ambient temperature and a temperature measured at a surface of the body.

13. The apparatus of claim 10, wherein the interior surface of the baffle constitutes a portion of a sphere surrounding the detector, a portion of the baffle above and opposite the sensitive area of the detector having an opening allowing the radiation to reach the sensitive area of the detector.

14. The apparatus of claim 13, wherein an exterior surface of the baffle being coated with a suitable black coating for absorbing stray radiation.

15. A method of noninvasively measuring a concentration of a substance in a body using an apparatus including a detector and an optical system, the method comprising the steps of:

detecting an infrared radiation value emitted by the body in a wavelength range including at least one wavelength characteristic of the substance;

measuring the temperature of the detector and one or more components of the optical system; and

correlating the temperatures of the detector and the one or more components of the optical system with a set of predetermined calibration parameters to correct the detected infrared radiation value for the effects of the emission of each of the detector and the one or more components of the optical system.

16. A method as in claim 15, further comprising the step of measuring the ambient temperature.

17. A method as in claim 16, further comprising the step of measuring the temperature of the body.

18. A method as in claim 15, furthering comprising the step of limiting the wavelength range of the detected infrared radiation value.

19. A method as in claim 18, further comprising the step of limiting the wavelength range of the detected infrared radiation value to a first wavelength range including at least one wavelength characteristic of the substance to provide a first detected radiation value, and limiting the wavelength range of the detected infrared radiation value to a second wavelength range wherein wavelengths characteristic of the substance are minimized to provide a second detected radiation value.

20. A method as in claim 19, wherein the first wavelength range comprises 8.5μ

to 10.0μ and

the second wavelength range comprises 10.5μ

to 15.0μ

.

21. A method as in claim 19, further comprising the steps of:

correcting the first and second detected radiation values for the effects of the emission of each of the detector and the one or more components of the optical system;

normalize the first and second detected radiation values for a blackbody reading; and

correlating the ratio of the first and second detected radiation values to the concentration of the substance in the body.