Nanocomposite optical strain gauge

Patent metadata

Field	Value
Publication number	US-10330541-B2
Application number	US-201514725365-A
Country	US
Kind code	B2
Filing date	May 29, 2015
Priority date	May 29, 2015
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

The pressure-detecting system utilizes a nanocomposite sensor with quantum dots embedded in a matrix. Under pressure, both the quantum dots and the matrix fluoresce when illuminated by a laser. A spectroscope detects the intensity of each fluorescence and sends the information to a data processor. The data processor calculates a ratio using the intensities. Comparing this ratio to ratios stored in a data object in a database provides a value for the pressure detected by the sensor. The data object contains multiple ratios, each correlated to a specific pressure during a calibration process for the sensor. This calibration process subjected the sensor to known pressures, with the resultant ratios calculated and stored in the data object, correlated to the appropriate pressures.

First claim

What is claimed is:

1. A pressure sensing system, comprising: a laser light source, wherein said laser light source transmits light in the visible spectrum; at least one nanocomposite pressure sensor, wherein said at least one nanocomposite pressure sensor comprises a plurality of quantum dots embedded in a sensor matrix, wherein under pressure, said quantum dots and said sensor matrix fluoresce when illuminated by said laser; a spectrometer operatively coupled to a data processor; a database operatively coupled to said data processor, said database comprising at least one data object, wherein said data object comprises an array to store a plurality of pressure values P and a plurality of fluorescence intensity ratio R F .

2. The system of claim 1 , wherein said laser light source is a solid-state laser having a power of 5 mW.

3. The system of claim 1 , wherein said at least one pressure sensor is a solid shape.

4. The system of claim 1 , wherein said at least one pressure sensor is a coating on an object.

5. The system of claim 1 , wherein said plurality of quantum dots are core-shell semiconducting nanocrystals.

6. The system of claim 5 , wherein said plurality of quantum dots are CdSe/ZnS core-shell quantum dots.

7. The system of claim 1 , wherein said plurality of quantum dots have a diameter of approximately 1 nm to approximately 10 nm.

8. The system of claim 1 , wherein said plurality of quantum dots have a maximum diameter variation of approximately 4 nm.

9. The system of claim 1 , wherein said sensor matrix is a polymer having a transmittance of approximately 95% to approximately 100% for the visible spectrum.

10. The system of claim 9 , wherein said sensor matrix is an epoxy.

11. The system of claim 1 , wherein said spectrometer is an optical bandpass detector.

12. The system of claim 1 , wherein said sensor matrix changes in intensity of fluorescence when subjected to tension or compression loading in the range of approximately 0.5 MPa to approximately 110 MPa, and wherein said intensity of fluorescence of the sensor matrix serves as a comparative baseline for an intensity of fluorescence of the plurality of quantum dots.

13. A method for sensing pressure using a nanocomposite pressure sensor, comprising the steps of: illuminating said nanocomposite pressure sensor with a laser light source, wherein said nanocomposite pressure sensor comprises a plurality of quantum dots embedded in a sensor matrix, wherein said laser light source transmits light in the visible spectrum; wherein under pressure, said quantum dots and said sensor matrix fluoresce when illuminated by said laser; detecting a returned quantum dot intensity of a quantum dot fluorescence using a spectrometer operatively coupled to a data processor; detecting a returned sensor matrix intensity of a sensor matrix fluorescence using said spectrometer; converting said returned quantum dot intensity and said returned sensor matrix intensity to a digital format using said spectrometer; transmitting said returned quantum dot intensity and said returned sensor matrix intensity to said data processor; calculating an actual fluorescence intensity ratio R FA from said returned quantum dot intensity and said returned sensor intensity; comparing said actual fluorescence intensity ratio R FA with fluorescence intensity ratios R F from a database operatively coupled to said data processor, said database comprising at least one data object, wherein said data object comprises an array storing a plurality of pressure values P and a plurality of fluorescence intensity ratio R F ; and outputting a pressure value P correlated to one of said plurality of fluorescence intensity ratios R F .

14. The method of claim 13 , further comprising the step of repeating said method using a different nanocomposite pressure sensor.

15. The method of claim 13 , wherein said sensor matrix changes in intensity of fluorescence when subjected to tension or compression loading in the range of approximately 0.5 MPa to approximately 110 MPa, and wherein said intensity of fluorescence of the sensor matrix serves as a comparative baseline for an intensity of fluorescence of the plurality of quantum dots.

16. A method for calibrating a nanocomposite pressure sensor, comprising the steps of: instantiating a data object for said nanocomposite pressure sensor, wherein said data object comprises an array to store a plurality of pressure values P and a plurality of fluorescence intensity ratio R.sub.F, wherein said nanocomposite pressure sensor comprises a plurality of quantum dots embedded in a sensor matrix and wherein under pressure, said quantum dots and said sensor matrix fluoresce when illuminated by said laser; and iteratively invoking a function n times, wherein said function comprises the steps of: placing said nanocomposite pressure sensor under a known load, wherein said known load has a pressure value P; illuminating said nanocomposite pressure sensor with a laser light source, wherein said laser light source transmits light in the visible spectrum; detecting a returned quantum dot intensity of a quantum dot fluorescence using a spectrometer operatively coupled to a data processor; detecting a returned sensor matrix intensity of a sensor matrix fluorescence using said spectrometer; converting said returned quantum dot intensity and said returned sensor matrix intensity to a digital format using said spectrometer; transmitting said returned quantum dot intensity and said returned sensor matrix intensity to said data processor; calculating a fluorescence intensity ratio R F using said returned quantum dot intensity and said returned sensor intensity; and updating said data object with said fluorescence intensity ratio R F and said pressure value P.

17. The method of claim 16 , further comprising the step of repeating said function using a different pressure value P.

18. The method of claim 16 , further comprising the step of calculating a best-fit line for said plurality of fluorescence intensity ratios R F and said plurality of pressure values P.

19. The method of claim 18 , wherein said best-fit line is calculated using a model selected from the group consisting of: hybrid Voigt, Gaussian or Lorentz distribution.

20. The method of claim 16 , wherein said sensor matrix changes in intensity of fluorescence when subjected to tension or compression loading in the range of approximately 0.5 MPa to approximately 110 MPa, and wherein said intensity of fluorescence of the sensor matrix serves as a comparative baseline for an intensity of fluorescence of the plurality of quantum dots.

Assignees

• Marsh Charles P
• Ford Kyle B
• Ajami Nassim E
• Collins Michael
• Us Army

Inventors

• Marsh Charles P
• Ford Kyle B
• Ajami Nassim E
• Collins Michael

Classifications

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G01N2021/6417

  Spectrofluorimetric devices · CPC title

• G01L1/24 Primary

  by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} · CPC title

• G01N2201/127

  Calibration; base line adjustment; drift compensation · CPC title

• G01N21/645

  Specially adapted constructive features of fluorimeters · CPC title