System and method for a self-calibrating non-invasive sensor

• US 6,889,153 B2
• Filed: 08/09/2001
• Issued: 05/03/2005
• Est. Priority Date: 08/09/2001
• Status: Expired due to Term

• Current Assignee: Medtor, LLC
• Original Assignee: Measurement Specialties, Inc. (France) (TE Connectivity Limited)
• Inventors: Dietiker, Thomas
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Pretlow, Demetrius
• Application Number:
  US10/149,779
• Publication Number:
  US 20030033102A1
• Time in Patent Office: 1,363 Days
• Field of Search: 702/85, 702/106, 702/104
• US Class Current: 702/104
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: G01J 1/08 Arrangements of light sources specially adapted for photometry standard sources, also using luminescent or radioactive material
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 2201/1211 for temperature
• CPC Class Codes: G01N 2201/12723 Self check capacity; automatic, periodic step of checking
• CPC Class Codes: H01L 27/14647 Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier

Abstract

A non-invasive emitter-photodiode sensor which is able to provide a data-stream corresponding to the actual wavelength of light emitted thereby allowing calibration of the sensor signal processing equipment and resulting in accurate measurements over a wider variation in emitter wavelength ranges.

Claims

1. A self-calibrating sensor system having at least one light source, the self-calibrating sensor system comprising:

a probe receiving incident light radiation from the at least one light source, the probe including a wavelength sensor comprising;

a first diode configured to receive short wavelengths from the incident light radiation and produce a first photocurrent signal; and

a second diode configured to receive short wavelengths from the incident light radiation and produce a second photocurrent signal; and

;

a calibration circuit in signal communication with the probe, the calibration circuit producing a calibrated signal corresponding to the received incident light radiation at the probe;

wherein the probe further includes a probe output circuit in signal communication with the calibration circuit, the probe output circuit producing a known sensor probe output signal when the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.

2. The self-calibrating sensor system of claim 1, wherein the probe output circuit is a differential amplifier.

3. The self-calibrating sensor system of claim 1, further including software that operates on the controller.

4. The self-calibrating sensor system of claim 1, wherein the software is capable of determining the wavelength of the incident light radiation.

5. The self-calibrating sensor system of claim 4, wherein the software is capable of compensating for wavelength variation of the incident light radiation caused by changes in temperature.

6. The self-calibrating sensor system of claim 1, further including a look-up table in signal communication with the controller.

7. A self-calibrating sensor system having at least one light source, the self-calibrating sensor system comprising:

first means for receiving incident light radiation from the lightsource, including means for receiving short wavelengths from the incident light radiation and producing a first photocurrent signal, and means for receiving long wavelengths from the incident light radiation and producing a second photocurrent signal;

means for producing a calibrated signal corresponding to the received incident light radiation at the first means; and

means for controlling the calibration circuit;

signal producing means

wherein the first receiving means further includes a second means for producing a known output signal when the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.

8. The self-calibrating sensor system of claim 7, wherein the second producing means is a differential amplifier.

9. The self-calibrating sensor system of claim 7, further including software that operates on the controlling means.

10. The self-calibrating sensor system of claim 7, wherein the software is capable of determining the wavelength of the incident light radiation.

11. The self-calibrating sensor system of claim 10, wherein the software is capable of compensating for wavelength variation of the incident light radiation caused by changes in temperature.

12. The self-calibrating sensor system of claim 7, further including a look-up table in signal communication with the controlling means.

13. A method for self-calibrating a sensor system having at least one light source, the method comprising the steps of:

receiving incident light radiation from the at least one light source;

receiving short wavelengths from the incident light radiation;

at a probe

receiving long wavelengths from the incident light radiation;

at the probe

producing a first photocurrent signal in response receiving short wavelengths from the incident light radiation;

producing a second photocurrent signal in response to receiving short wavelengths from the incident light radiation;

comparing the first photocurrent signal to the second photocurrent signal;

determining the wavelength of the incident light radiation; and

producing a calibrated signal corresponding to the received incident light radiation at the probe.

14. The method of claim 13, further comprising the step of determining whether the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.

15. The method of claim 13, further comprising the step of compensating the determined wavelength of the incident light radiation for temperature variation.

16. A computer-readable medium for self-calibrating a sensor system having at least one light source, the computer-readable medium comprising:

logic configured for receiving incident light radiation from the at least one light source at a probe;

logic configured for receiving short wavelengths from the incident light radiation at a first diode;

logic for receiving long wavelengths from the incident light radiation at a second diode;

logic configured for producing a first photocurrent signal from the first diode in response to receiving short wavelengths from the incident light radiation;

logic configured for producing a second photocurrent signal from the second diode in response to receiving long wavelengths from the incident light radiation;

logic configured for producing a calibrated signal corresponding to the received incident light radiation at the probe; and

logic configured for determining the wavelength of the incident light radiation by comparing the first photocurrent signal to the second photocurrent signal.

17. The computer-readable medium of claim 16, further comprising logic configured for determining whether the first photocurrent signal and second photocurrent signal are approximately equal in magnitude.

18. The computer-readable medium of claim 17, further comprising logic configured for compensating the determined wavelength of the incident light radiation for temperature variation.