Smart fiber optic sensors systems and methods for quantitative optical spectroscopy

• US 9,091,637 B2
• Filed: 12/06/2010
• Issued: 07/28/2015
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Yu, Bing, Ramanujam, Nirmala
• Primary Examiner(s): Nur, Abdullahi
• Application Number:
  US13/513,458
• Publication Number:
  US 20130100439A1
• Time in Patent Office: 1,695 Days
• Field of Search: 356 72- 73
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0228 using calibration standards
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/4331 of the cervix A61B5/435 takes precedence
• CPC Class Codes: A61B 5/4552 Evaluating soft tissue within the mouth, e.g. gums or tongue
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: G01J 3/0218 using optical fibers
• 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: G01L 9/0079 with Fabry-Perot arrangements
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 2201/0627 Use of several LED's for spectral resolution
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides

Abstract

Smart fiber optic sensors, systems, and methods for performing quantitative optical spectroscopy are disclosed. In one embodiment, smart fiber optic sensor can include a sensing channel, a calibration channel, and a pressure sensing channel. External force or pressure can be calculated at pressure sensing channel for monitoring and controlling pressure at a sensor-specimen interface thereby ensuring more accurate specimen spectral data is collected. Contact pressure can be adjusted to remain within a specified range. A calibration light of the calibration channel and an illumination light of the sensing channel can be generated simultaneously from a shared light source. Pressure sensing channel can transmit light from a second light source and collect pressure spectral data.

Claims

1. A smart fiber optic sensor comprising:

a sensing channel for illuminating a specimen and for collecting spectral reflections from the specimen from which specimen spectral data can be determined;

a pressure sensing channel for collecting pressure sensor spectral reflections from which a contact pressure can be determined;

a calibration channel for obtaining calibration spectral reflections usable for correcting the specimen spectral data; and

a first light source for transmitting light having a first emission spectra to the sensing channel and calibration channel and a second light source for transmitting light having a second emission spectra to the pressure sensing channel, wherein the first and second emission spectra are non-overlapping.

2. The sensor according to claim 1, wherein the pressure sensing channel comprises a fiber optic pressure sensor.

3. The sensor according to claim 2, wherein the fiber optic pressure sensor comprises a diaphragm-based Fabry-Perot interferometric (DFPI) pressure sensor.

4. The sensor according to claim 3, further comprising a processing unit for calculating the contact pressure based on the cavity length of the DFPI from the pressure sensor spectral reflections.

5. The sensor according to claim 4, wherein the processing unit determines whether to save the specimen spectral reflections based on the contact pressure.

6. The sensor according to claim 1, wherein the sensing channel comprises at least one illumination fiber for transmitting light from the first light source to the specimen for generating the specimen spectral reflections.

7. The sensor according to claim 6, wherein the sensing channel comprises at least one detection fiber for detecting light diffusely reflected from the specimen at one or more wavelengths and communicating the diffusely reflected light from the specimen.

8. The sensor according to claim 6, wherein the calibration channel comprises:

a reflector;

at least one calibration source fiber for communicating calibration light from the first light source to the reflector;

at least one calibration return fiber for communicating the calibration spectral reflections from the reflector; and

a spectrometer for receiving the calibration spectral reflections and for generating calibration spectral data, wherein the calibration light and the first illumination light are generated simultaneously from the first light source.

9. The sensor according to claim 8, wherein the spectrometer generates the calibration spectral data based on the calibration light contemporaneously with the collection of spectral reflections from the specimen.

10. A smart fiber optic sensor system comprising:

a smart fiber optic sensor comprising;

a sensing channel for illuminating a specimen and for collecting spectral reflections from the specimen from which specimen spectral data can be determined;

a pressure sensing channel for collecting pressure sensor spectral reflections from which a contact pressure can be determined; and

a calibration channel for obtaining calibration spectral reflections usable for correcting the specimen spectral data, wherein the calibration channel comprises;

a reflector;

at least one calibration source fiber for communicating calibration light from the first light source to the reflector;

at least one calibration return fiber for communicating the calibration spectral reflections from the reflector; and

a spectrometer for receiving the calibration spectral reflections and for generating calibration spectral data, wherein the calibration light and the first illumination light are generated simultaneously from the first light source; and

a processing unit, coupled to the each of the sensing channel, the pressure sensing channel, and the calibration channel, the processing unit being adapted to receive and correct the specimen spectral data and to calculate a contact pressure at a sensor/specimen interface.

11. The sensor system according to claim 10, wherein the contact pressure at the sensor/specimen interface is calculated real time.

12. The sensor system according to claim 11, wherein the processing unit calculates and displays the contact pressure real-time by determining a cavity length of the DFPI using the spectral reflections obtained by the pressure sensing channel.

13. The sensor system according to claim 12, wherein the spectrometer generates calibration spectral data based on the calibration spectral reflections contemporaneously with the detection of spectral reflections from the specimen.

14. The sensor system according to claim 10, wherein the pressure sensing channel comprises a diaphragm-based Fabry-Perot interferometric (DFPI) pressure sensor.

15. The sensor according to claim 10, wherein the sensing channel further comprises at least one illumination fiber for transmitting light from a first light source to the specimen used for generating the specimen spectral data, at least one detection fiber for communicating light diffusely reflected from the specimen at one or more wavelengths, and a spectrometer for receiving the light diffusely reflected from the specimen and generating the specimen spectral data.

16. The sensor according to claim 10, wherein the spectrometer generates the calibration spectral data associated with the calibration light contemporaneously with the collection of the spectral reflections from the specimen.

17. The sensor system according to claim 16, wherein the processing unit analyzes the calibrated specimen spectral data and stores the calibrated specimen spectral data if the contact pressure is within a predetermined range.

18. A method for utilizing a smart fiber optic sensor for measuring a specimen, the method comprising:

contacting the specimen with the smart fiber optic sensor;

generating, using the smart fiber optic sensor, specimen spectral data, pressure sensor spectral data, and calibration spectral data, wherein generating the specimen spectral data comprises;

transmitting a first illumination light via at least one illumination fiber from a first light source to the specimen;

collecting spectral reflections at a spectrometer using at least one detection fiber, the specimen spectral reflections comprising the first illumination light diffusely reflected from the specimen at one or more wavelengths; and

generating, using the spectrometer, the specimen spectral data based on the reflections; and

wherein generating the calibration spectral data comprises;

transmitting calibration light to a reflector via at least one calibration source fiber, wherein the calibration light and the first illumination light are generated simultaneously from the first light source;

collecting calibration spectral reflections at the spectrometer using at least one calibration return fiber; and

generating, using the spectrometer, the calibration spectral data from the calibration reflections;

calculating a contact pressure at an interface of the smart fiber optic sensor and the specimen using the pressure sensor spectral data; and

correcting specimen spectral data using the calibration spectral data.

19. The method according to claim 18, further comprising analyzing and storing the specimen spectral data.

20. The method according to claim 19, wherein analyzing and storing the collected spectral data comprises analyzing the corrected specimen spectral data to extract optical and physiological properties from the specimen using an inverse Monte Carlo model for reflectance.

21. The method according to claim 18, wherein generating the pressure sensor spectral data comprises:

transmitting a second illumination light using at least one optical fiber to a diaphragm-based Fabry-Perot interferometric (DFPI) pressure sensor; and

collecting pressure sensor spectral reflections reflected by the pressure sensor at the spectrometer via the same optical fiber; and

generating, using the spectrometer, the pressure sensor spectral data based on the pressure sensor spectral reflections.

22. The method according to 21, wherein calculating the contact pressure comprises:

determining the cavity length of the DFPI using the pressure sensor spectral data;

calculating a contact pressure of the DFPI/specimen interface using the cavity length of the DFPI.

23. The method according to claim 18, further comprising determining whether to analyze and save the specimen spectral data based on the calculated contact pressure.

24. The method according to claim 18, further comprising adjusting a pressure at which the smart fiber optic sensor contacts the specimen such that the contact pressure stays within an optimal preset pressure range.

25. The method according to claim 18, wherein emission spectra respectively used to determine the specimen spectral data and the contact pressure are non-overlapping.