Miniaturized fluorescence analysis system

Abstract

According to embodiments of the present invention, a fluorescence analysis system includes a light emitting diode (LED) array to excite a fluorophor sample for analysis. The system includes an LED array driver that pulses the LEDs in the array with currents in excess of maximum rated current at low duty cycles to reduce LED degradation over time. An LED selection optimization process and software select the LEDs to be included in the array from among various colors and currents to be applied. The LED selection optimization process and software take filters and attenuation into consideration.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 606,000, filed Aug. 31, 2004.GOVERNMENT LICENSE RIGHTS [0002] The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant No. NIH 1-P50-HG002360-01.BACKGROUND [0003] 1. Field [0004] Embodiments of the present invention relate to fluorescence analysis systems and in particular to light emitting diode (LED)-based fluorescence analysis systems. [0005] 2. Discussion of Related Art [0006] Fluorescence is the emission of light by molecules which have absorbed light. The fluorescing characteristics of such molecules (called fluorophors) are useful in detecting and tagging various microbiological events. The emission signal is shifted to higher wavelengths (Stokes-Shift) in relation to the excitation signal because the energy of t...

AI Technical Summary

Benefits of technology

[0012] Embodiments of the present invention are directed to automated and modular optimization of fluorescence analysis system that may maximize signal extraction (SNR) from an excited fluorophor. In one embodiment, the system includes an array of light emitting diodes (LEDs) that emit excitation light. The excitation light may have a first color and / or wavelength (blue, blue-green, green, purple, or other suitable color / wavelength. The color and / or wavelength of the excitation light of one LED may be different than the color and / or wavelength of another excitation light of one LED.

[0025] As will be described below, the optimization software takes into account a variety of factors of practical fluorescence analysis including optics, photodetector properties, attenuation in the sample itself, and leakage of the excitation signal to the output signal path. While most fluorometer systems use a single light source such as a Xenon or Mercury lamp, in embodiments of the present invention the optimization software relies on a combination of several LEDs in an array driven at various nominal and overdrive currents. Overdriving the LEDs enables spectral shifts from nominal peak excitation wavelengths that increase the flexibility and intensity of spectra identified by optimization software. Given a fluorophor, environmental conditions, and optical path constraints, the optimization software may generate the best possible combination of LEDs to excite the sample and maximize the emission signal collected in the output path.

Problems solved by technology

The use of LEDs, however, is often limited by three primary factors: (a) the broadband output of an LED often interferes with the measurement of emission signal; (b) the power (intensity) of light generated by an LED (mWatts) is often small compared to white light source (Watts) counterparts; and (c) the excitation peaks of the LED are often not well matched to the absorption efficiency of the fluorophor under analysis.

The use of LEDs, for this reason, has been largely limited to high concentration applications where emitted fluorescence is sufficiently high (and noise sufficiently low) that LED limitations do not restrict effective measurements of the sample under analysis.

In many approaches using LEDs, the choice of LED (or LEDs) is usually not optimized prior to the collection of data by the fluorescence analysis system.

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