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Axial illumination for capillary electrophoresis

Axial illumination for capillary electrophoresis description/claims

This application is a continuation application which claims the benefit of U.S. Provisional Application No. 60/653,606 filed Feb. 16, 2005, the disclosure of which is herein incorporated by reference in its entirety. Furthermore, this application incorporates by reference U.S. Provisional Application No. 60/774,462, filed Feb. 16, 2006.

The present teachings relate to devices and methods for generating and detecting fluorescence.

Molecular biology and other sciences can utilize fluorescent detection because of its wide acceptance and sensitivity. Examples of methods utilizing fluorescent detection include chromatography and electrophoresis. Fluorescent light can be generated by exciting dyes in a sample using excitation light or chemical means. The fluorescent light emitted can be diffuse due to low concentrations of dye in the sample. It is desirable to collect more of the diffuse light to increase the efficiency of fluorescent detection.

The fluorescent light emitted can be proportional to the amount of excitation light that can be directed to the detection zone. For non-coherent light sources, such as, for example, light emitting diodes (LEDs), filament lamps, and arc lamps, only a small amount of the light can typically be directed through the wall of the sample housing to the detection zone. To provide sufficiently high irradiance of excitation light at the detection zone, lasers have been used to focus light through the wall of the sample housing. Lasers at desirable wavelengths, however, are often large, expensive, and consume a lot of power.

Due to the coherent nature of laser light, lasers have also been used to focus light into an end of a tube shaped sample housing having an inner core to illuminate the detection zone. Coupling illumination to propagate along an axis of a sample housing non-laser excitation light, however, has not been realized because of problems coupling non-coherent light into the sample housing. For example, in the case where the housing is a capillary with an inner core, it is difficult to couple non-coherent light into the core to propagate along the axis of the capillary.

Fluorescent light detection systems can benefit from smaller, lower cost, and lower power excitation light sources. It is desirable to replace lasers with non-coherent excitation light sources that provide sufficient excitation light at the detection zone by, for example, coupling illumination to propagate down housing to the detection zone.

It is to be understood that both the foregoing general description and the following description of various embodiments are exemplary and explanatory only and are not restrictive.

In various embodiments, the present teachings provide an excitation system for analyzing samples. The system further comprises: a non-coherent light source; a housing, wherein the housing transports samples and propagates light from the non-coherent light source by total internal reflection; and a coupling optical element configured to introduce light from the non-coherent light source into the housing through a wall of the housing.

In other embodiments, the present teachings provide a fluorescence excitation system for analyzing samples comprising: a non-coherent light source; a housing, wherein the housing transports the samples and propagates light from the non-coherent light source; and at least one high NA optical element configured to focus light from the non-coherent light source onto an end of the housing.

In still other embodiments, the present teachings provide a method for exciting fluorescence of samples. The method further comprises: transporting a plurality of samples through a detection zone with a capillary; directing a non-coherent light into the capillary with a coupling optical element; and illuminating the detection zone with the non-coherent light propagating through the capillary.

In further embodiments, the present teachings provide a system for analyzing samples comprising: a light source that provides a non-coherent excitation light; at least one housing, wherein the housing transports samples and propagates the non-coherent excitation light by total internal reflection; a coupling optical element configured to introduce the non-coherent excitation light into the at least one housing through a wall of the at least one housing; and at least one NA enhancing optical element to collect an emitted fluorescence, wherein the NA enhancing optical element is constructed of a first material and the housing is constructed of a second material, wherein the first material has a greater index of refraction than the second material.

In still further embodiments, the present teachings provide a system for analyzing samples comprising: a light source that provides a non-coherent excitation light; at least one housing, wherein the housing transports samples and propagates the non-coherent excitation light by total internal reflection; a coupling optical element configured to introduce the non-coherent excitation light into the at least one housing through a wall of the at least one housing; and at least one NA enhancing optical element to collect an emitted fluorescence, wherein the NA enhancing optical element is constructed of a first material and the housing is constructed of a second material, wherein the first material has a greater index of refraction than the second material.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments. In the drawings,

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