Miniaturized fluorescence analysis system

• US 7,583,381 B2
• Filed: 04/22/2008
• Issued: 09/01/2009
• Est. Priority Date: 08/31/2004
• Status: Expired due to Fees

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Wilson, Denise M., Moe, Andrew E.
• Primary Examiner(s): Geisel; Kara E
• Application Number:
  US12/107,718
• Publication Number:
  US 20080225290A1
• Time in Patent Office: 497 Days
• Field of Search: 356/317, 356/417, 250/458.1
• US Class Current: 356/417
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/4406 Fluorescence spectrometry
• CPC Class Codes: G01N 21/645 Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides

Abstract

According to embodiments of the present invention, a fluorescence analysis system includes a light emitting diode to excite a fluorophor sample for analysis. The system includes an LED driver that pulses the LEDs in the array with currents in excess of maximum rated current at low duty cycles. One embodiment receives a first drive current at a light emitting diode (LED), emits excitation light having a first color and/or first wavelength band in response to the first drive current, receives a second drive current at the LED, and emits excitation light having a second color and/or second wavelength band in response to the second drive current, wherein at least one of the drive currents is greater than a nominal drive current for the LED.

Claims

1. An apparatus for performing fluorescence analysis using a plurality of drive currents, comprising:

a light emitting diode (LED);

control electronics to apply a plurality of drive currents to the LED, wherein a first drive current in the plurality of drive currents is to cause the LED to emit excitation light having a first color and/or first wavelength band, wherein a second drive current in the plurality of drive currents is to cause the LED to emit excitation light having a second color and/or second wavelength band, wherein at least one of the drive currents is greater than a nominal drive current for the LED;

optics to couple the excitation light from the LED to a holder for a fluorophor, the fluorophor to emit light in response to the excitation light from the LED, the light emitted from the fluorophor having a color and/or wavelength band that is different from the color and/or wavelength band of the excitation light coupled to the holder;

one or more photodetectors; and

an optical signal path to couple the light from the holder to the photodetector.

2. The apparatus of claim 1, wherein at least one drive current has a variable duty cycle.

3. The apparatus of claim 1, wherein the control electronics are further to pulse at least one drive current to the LED.

4. The apparatus of claim 3, wherein the drive current is greater than a rated maximum current for the LED.

5. The apparatus of claim 3, wherein the control electronics comprise at least one active amplification circuit.

6. The apparatus of claim 1, wherein the first and second colors and the color emitted from the fluorophor are selected from at least one of blue, green, purple, and blue-green.

7. The apparatus of claim 1, wherein the optics to couple the excitation light from the LED to the holder for the fluorophor comprise an individual optical fiber bundle coupled to the LED, wherein the optical fiber bundle comprises a plurality of optical fibers.

8. The apparatus of claim 7, wherein the optical fiber bundle is bundled together to aggregate the excitation light from the LED into a single light beam having a substantially uniform intensity profile and/or a substantially uniform wavelength band distribution and to couple the single light beam to the holder for the fluorophor.

9. The apparatus of claim 8, wherein the plurality of optical fibers in the optical fiber bundle are bundled together in a random manner.

10. The apparatus of claim 8, further comprising a beam splitter to split off a small portion of the single light beam.

11. The apparatus of claim 10, further comprising high gain, low noise circuitry to measure the intensity of the small portion of the single light beam as a function of drive current.

12. The apparatus of claim 11, further comprising circuitry to adjust drive current to the LED in response to the measured intensity of the small portion of the single light beam, the circuitry comprising a feedback loop.

13. The apparatus of claim 11, wherein the circuitry to measure the intensity of the small portion of the single light beam as a function of the drive current comprises a spectrophotometer or spectrometer.

14. The apparatus of claim 8, further comprising at least one individual PIN diode coupled to the LED to detect excitation light emitted from the LED.

15. The apparatus of claim 14, further comprising circuitry to adjust at least one individual drive current to the LED in response to the detected excitation light emitted from the LED.

16. The apparatus of claim 1, wherein the holder for the fluorophor is a cuvette.

17. The apparatus of claim 1, wherein the photodetector is selected from at least one of a photomultiplier tube, an avalanche photodiode, photodiode, phototransistor, and a charge-coupled device (CCD).

18. A method for performing fluorescence analysis using a plurality of drive currents, comprising:

receiving a first drive current in the plurality of drive currents at a light emitting diode (LED);

emitting excitation light having a first color and/or first wavelength band in response to the first drive current;

receiving a second or more drive current in the plurality of drive currents at the LED;

emitting excitation light having a second color and/or second wavelength band in response to the second drive current, wherein at least one of the drive currents is greater than a nominal drive current for the LED;

coupling the excitation light from the LED to a sample having a fluorophor therein;

emitting light from the fluorophor in response to the excitation light, the light emitted from the fluorophor having a color and/or wavelength band that is different from the color and/or wavelength band of the excitation light coupled to the holder, the light emitted from the fluorophor also being different from the emitted light using first drive current and the second or more drive current; and

coupling the light from emitted from the fluorophor to one or more photodetectors, the photodetectors having a spectral sensitivity to capture differences in color or wavelength band between emissions corresponding to the first drive current and the second or more drive currents.

19. The method of claim 18, further comprising varying the duty cycle of the first drive current.

20. The method of claim 18, further comprising varying the duty cycle of the second drive current.

21. The method of claim 18, further comprising measuring an intensity of a portion of the excitation light.

22. The method of claim 21, further comprising using feedback to adjust the first and/or the second drive currents in response to measuring the intensity of the portion of the excitation light.

23. A method for performing fluorescence analysis, comprising:

receiving a first drive current at a light emitting diode (LED);

emitting excitation light having a first color and/or first wavelength band in response to the first drive current;

receiving a second drive current at the LED; and

emitting excitation light having a second color and/or second wavelength band in response to the second drive current, wherein at least one of the drive currents is greater than a nominal drive current for the LED

detecting the excitation light emitted from the LED;

coupling the excitation light from the LED to a holder for a fluorophor;

emitting light from the excitation light, the light emitted from the fluorophor having a color and/or wavelength band that is different from the color and/or wavelength band of the excitation light coupled to the holder; and

coupling the light emitted from the fluorophor to a photodetector.