Optics: measuring and testing – By dispersed light spectroscopy – With sample excitation
Reexamination Certificate
1999-04-06
2001-11-13
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
With sample excitation
C356S417000, C250S458100
Reexamination Certificate
active
06317206
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for the detection of a fluorescent dye in samples, comprising a device for exciting the fluorescent dye to be detected, said device comprising a surface provided for the application of samples and an excitation light coupling device by means of which excitation light from a predefined direction of impingement can be coupled into the device in such a way that, by means of an evanescent field of the coupled light, the fluorescent dye to be detected can be excited in the samples applied, and further comprising a means for the detection of the fluorescent light emitted by the fluorescent dye to be detected.
BACKGROUND ART
Such a device is known from the article “A Planar Indium Phosphate Monomode Waveguide Evanescent Field Immunosensor” by A. N. Sloper, J. K. Deacon and M. T. Flanagan, in Sensors and Actuators, B1 (1990), pp. 589-591.
This article particularly refers to a first embodiment in which a thin-film waveguide is provided on a glass substrate. By means of a device for coupling in excitation light, which is fixed relative to the thin-film waveguide, monochromatic laser light is coupled into the thin-film waveguide in such a way that it is conducted through the thin-film waveguide parallel to the surface thereof. The fluorescent dye which is contained in a sample applied to the thin-film waveguide is excited by the evanescent field of the laser light propagating along the thin-film waveguide. The fluorescent light emitted by the fluorescent dye is finally detected by a photomultiplier means.
The article further reveals a second embodiment of the above-described device, in which the device for exciting the fluorescent dye to be detected is provided in the form of a glass plate with a device for coupling in excitation light, monochromatic laser light from a light source which is fixed relative to the glass plate being coupled into said glass plate by said excitation light coupling device in such a way that it is conducted through said glass plate at an angle of total reflectance.
Just as in the case of the thin-film waveguide, a fluorescent dye contained in a sample applied to the glass plate is excited by the evanescent field of the laser light also in the case of this embodiment. The fluorescent light resulting from this excitation is then again detected by a photomultiplier means.
A disadvantage of both embodiments known from the prior art is, however, that these embodiments are very difficult to handle in practical applications, i.e. when a plurality of samples is to be analyzed. In particular, the thin-film waveguide and the glass plate, respectively, must be cleaned after each analysis of a sample, whereupon a new sample has to be applied and the thin-film waveguide or the glass plate with the sample applied thereto has to be adjusted with respect to the light source and the detecting means. An analysis of a plurality of samples by means of the device known from the prior art is therefore very time-consuming.
SUMMARY OF THE INVENTION
In view of this disadvantage of the devices according to the prior art, it is the object of the present invention to improve the handling characteristics of the known device for detecting one or several fluorescent dyes, especially with regard to the analysis of a plurality of samples.
This object is achieved by a device of the type cited at the start, which is characterized in that the device for exciting the fluorescent dye to be detected is provided in such a way that the surface to which the samples are to be applied is movable relative to the direction of impingement so as to excite the fluorescent dye to be detected in different subsections of said surface.
Due to the fact that the excitation device can be moved relative to the direction of impingement, the surface provided for the application of samples can have applied thereto a plurality of samples at the same time, and the respective fluorescent dye contained in said samples can be excited in a predefined sequence, and, finally, the fluorescent light emitted by the fluorescent dye can be detected by the means used for detecting the fluorescent light.
According to a preferred embodiment of the present invention, the detecting means is located opposite the surface in such a way that said surface is scanned completely when a complete movement of said surface is carried out. This permits samples to be applied all over the surface of the device for exciting the fluorescent dye, whereby the surface is optimally utilized.
The detecting means can, for example, be provided with a linear photodiode array or a CCD array. Alternatively, the detecting means can be provided with a detector, in particular a photomultiplier tube, which is arranged such that it is guidable along a predefined surface scanning direction. Such adapted detecting means permit the whole surface of the device used for exciting the fluorescent dye to be scanned completely and in a simple way, thus ensuring that all samples applied are analyzed.
If necessary, and in order to enhance the quality of the detection signal, the detecting means can be provided with a lens system and/or a colour filter means adjusted to the wavelength of the fluorescent light to be detected by said means. This lens system permits the emitted fluorescent light to be focussed onto the detecting means, whereby a higher local resolution on the detecting means can be achieved. Due to the fact that the filter means is adjusted to the fluorescent light, it can be guaranteed that it is only fluorescent light that will be detected by the detecting means and that the detection result will not be influenced by other light radiation, such as stray light of excitation.
In accordance with a first alternative, the device for exciting the fluorescent dye to be detected can be provided in such a way that its surface carries out a rotational movement relative to the direction of impingement. In this case, the surface can be a rotationally-symmetric, in particular a circular-ring surface in an advantageous manner. This arrangement permits a particularly effective utilization of the surface available. In addition, the rotational movement of the surface can be realized with comparatively simple mechanical means.
In accordance with an advantageous embodiment, at least one further detecting means can be provided; in particular said first detecting means and each further detecting means can be arranged parallel to the surface and at a predefined angle relative to each other. This measure helps to reduce the measuring time, corresponding to the number of the additional detecting means, still further. This at least one further detecting means can also be provided with a lens system and/or a colour filter means adjusted to the wavelength of the fluorescent light to be detected by said means.
The first and/or the at least one further detecting means can be provided with various colour filter means. In this way, a fluorescent dye emitting fluorescent light at different wavelengths or, alternatively, different fluorescent dyes can be detected simultaneously, whereby the measuring time can again be reduced in comparison with the device known from the prior art.
If linear photodiode arrays or CCD arrays are used in connection with a surface carrying out a rotational movement, it will be advantageous to orientate said photodiode arrays or CCD arrays in a substantially radial direction. Similarly, if a photomultiplier tube is used, said photomultiplier tube should be provided such that it is guidable in a substantially radial surface scanning direction. By means of this measure, the total number of means used for the detection can be maximized.
According to a second alterantive, the device for exciting the fluorescent dye to be detected can be provided in such a way that the surface carries out a translational movement relative to the direction of impingement.
In order to simplify the manufacturing process, it will be advantageous to provide the surface with a substantially rectangular shape.
When linear photodiode
Bodenseewerk Perkin-Elmer GmbH
Evans F. L.
Perman & Green LLP
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