ARRANGEMENT FOR OPERATING A BIOSENSOR AND ARRANGEMENT FOR DETERMINING THE GLUCOSE CONTENT IN THE BLOOD

Abstract

An arrangement for operating a biosensor emitting radiation includes an excitation light source, which generates at least one excitation radiation for the biosensor; a coupling fiber, at the entry surface of which the excitation radiation is coupled in; an optical Y-coupler, including an excitation arm, which is connected to the exit surface of the coupling fiber, a detector arm, which is connected to an optical detector, and a sensor foot, which can be connected to the biosensor. The excitation arm has a conical shape. The radiation axis of the excitation arm includes an angle in the range of 5° to 70° with the main radiation axis of the detector arm. The diameter of the excitation arm at the connecting point to the detector arm is less than two thirds the diameter of the detector arm. An arrangement for determining the glucose content blood is also provided.

Claims

1. An arrangement for operating a biosensor emitting radiation, comprising: an excitation light source, which generates at least one excitation radiation for the biosensor; a coupling fiber, at the entry surface of which the excitation radiation is coupled in; an optical Y-coupler, including an excitation arm, which is connected to the exit surface of the coupling fiber, a detector arm, which is connected to an optical detector, and a sensor foot, which can be connected to the biosensor, the excitation arm having a conical shape, the radiation axis of the excitation arm including an angle in the range of 5° to 70° with the main radiation axis of the detector arm (13), and the diameter of the excitation arm at the connecting point to the detector arm being less than two thirds the diameter of the detector arm.

2. The arrangement according to claim 1, wherein characterized in that the diameter of the excitation arm at the connecting point is less than half as large as at the entry surface thereof.

3. The arrangement according to claim 1, wherein the detector arm and the sensor have a shared main radiation axis.

4. The arrangement according to claim 1, wherein any one of claims 1 the excitation light source is an LED chip, the emission plane of which is positioned at a distance of 0.1 to 10 times the diameter of the coupling fiber from the entry surface of the coupling fiber.

5. The arrangement according to claim 4, wherein the coupling fiber has a length that is 7 times to 13 times the distance between the excitation light source and the entry surface of the coupling fiber, in particular in the range of 7 to 13 mm.

6. The arrangement according to claim 4, wherein the entry surface of the coupling fiber is designed as a planar, spherical, aspherical or free-form surface.

7. The arrangement according claim 1, wherein a cut-off filter, which filters the wavelength of the radiation emittable by the biosensor out of the excitation radiation, is arranged between the exit surface of the coupling fiber and the entry surface of the excitation arm.

8. The arrangement according to claim 1, wherein the coupling fiber is designed with a rectilinearly extending longitudinal axis.

9. The arrangement according to claim 7, wherein the cut-off filter is composed of a carrier glass including optical filter layers applied thereon, the exit surface of the coupling fiber preferably being glued to the filter layers.

10. The arrangement according to claim 7, wherein a colored glass piece in waveguide form is arranged between the carrier glass and the entry surface of the excitation arm.

11. The arrangement according to claim 1, wherein a lens is arranged between the exit surface of the detector arm and the detector for collimating the radiation emitted by the biosensor.

12. The arrangement according to claim 1, wherein an optical filter, which blocks incoming fractions of the excitation radiation, is arranged between the lens and the detector.

13. The arrangement according to claim 1, wherein a colored glass piece in waveguide form is arranged at the exit-side end of the detector arm.

14. The arrangement according to claim 1, wherein the excitation light source, the coupling fiber, the Y-coupler and the optical detector are integrated in a shared housing.

15. The arrangement according to claim 1, wherein the sensor foot comprises a curved section, in which a beam deflection is carried out at an angle of more than 45°, and preferably of approximately 90°.

16. The arrangement according to claim 15, wherein a beam-deflecting, toric surface is formed in the sensor foot.

17. An arrangement for determining the glucose content, in particular of blood, comprising: a biosensor, which can be implanted into tissue and emits radiation upon excitation; an excitation light source, which generates at least an excitation radiation for the biosensor; a coupling fiber, at the entry surface of which the excitation radiation is coupled in; an optical Y-coupler, including an excitation arm, which is connected to the exit surface of the coupling fiber, a detector arm, which is connected to an optical detector, and a sensor foot, which is connected to the biosensor, the excitation arm having a conical shape, the radiation axis of the excitation arm including an angle in the range of 5° to 70° with the main radiation axis of the detector arm (13), and the diameter of the excitation arm at the position of the connecting point to the detector arm being less than two thirds the diameter of the detector arm.

18. The arrangement according to claim 17, wherein the biosensor is formed as an optical fiber, which includes glucose-sensitive fluorescent luminophores at the exit surface thereof, which upon excitation by the excitation radiation emit fluorescent radiation having a fluorescent wavelength.

19. The arrangement according to claim 17, comprising an arrangement for operating a biosensor including: an excitation light source, which generates at least one excitation radiation for the biosensor; a coupling fiber, at the entry surface of which the excitation radiation is coupled in; an optical Y-coupler, including an excitation arm, which is connected to the exit surface of the coupling fiber, a detector arm, which is connected to an optical detector, and a sensor foot, which can be connected to the biosensor, the excitation arm having a conical shape, the radiation axis of the excitation arm including an angle in the range of 5° to 70° with the main radiation axis of the detector arm, and the diameter of the excitation arm at the connecting point to the detector arm being less than two thirds the diameter of the detector arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further advantages and details of the invention will be apparent from the following description of preferred embodiments with reference to the drawings. In the drawings:

[0030] FIG. 1 shows a schematic diagram of a first embodiment of an arrangement according to the invention for operating a biosensor;

[0031] FIG. 2 shows a schematic diagram of a second embodiment of the arrangement for operating the biosensor; and

[0032] FIG. 3 shows an optical beam path in a sensor foot for beam deflection and for coupling into or outcoupling from the sensor fiber, with low optical losses.

DETAILED DESCRIPTION OF THE INVENTION

[0033] FIG. 1 shows an arrangement for operating a biosensor in a simplified lateral illustration. The biosensor is formed as a sensor fiber 01 here, which at the free end thereof is equipped with immobilized, glucose-sensitive fluorescent luminophores 02. Upon excitation by an excitation radiation, these fluorescent luminophores emit fluorescent radiation, the intensity of which is dependent on the glucose concentration in a medium in which the end of the biosensor is positioned. The medium can in particular be blood.

[0034] The arrangement for operating the biosensor includes an LED chip 03 as an excitation light source, preferably a thin-film LED. The LED chip 03 emits the excitation radiation and couples it at a flat angle into a coupling fiber 04. The angle between the excitation radiation and the core of the coupling fiber is preferably <30°. For this purpose, the LED 03 is positioned spaced approximately 1 mm apart from the entry surface of the coupling fiber 04 in the shown embodiment. The entry surface of the coupling fiber can be configured as a free-form, spherical, aspherical or planar surface. The coupling fiber 04 has a diameter of 0.5 mm and a length of 10 mm, for example. The exit surface of the coupling fiber 04 is attached to a carrier glass 07 by way of an adhesive 06. The carrier glass 07 is equipped with one or more filter layers 08 so as to act as a cut-off filter and to filter the wavelength of the fluorescent radiation that is emitted by the fluorescent luminophores 02 out of the excitation radiation. A first colored glass piece 09, which enhances the action of the cut-off filter, follows the carrier glass 07 in the propagation direction of the excitation radiation. The first colored glass piece 09 is configured in the form of a waveguide and, on the opposite side, adjoins an excitation arm 11 of an optical Y-coupler 12. The excitation arm 11 and the first colored glass piece 09 have a cross-section that tapers in the radiation direction. The diameter of the excitation arm 11 at the end thereof facing away from the coupling fiber 04 is thus only 0.1 to 0.2 mm, for example.

[0035] The Y-coupler 12 additionally includes a detector arm 13 and a sensor foot 14. At a connecting point 16, the excitation arm 11 joins the material that, otherwise, is continuous from the detector arm 13 to the sensor foot 14. At the connecting point 16, the detector arm 13 and the excitation arm 11 include an angle in the range of 5° to 70°, preferably 5° to 30°, and particularly preferably approximately 15°. The main radiation axes of the detector arm 13 and of the sensor foot 14 extend coaxially in the shown embodiment. In modified embodiments, the main radiation axes of the detector arm and of the sensor foot, however, can also extend at an angle with respect to one another, for example at a change in angle of 10° to 40°. The sensor foot 14 is configured to be flexible or curved at the end thereof facing away from the connecting point 16, so as to be able to be connected to the sensor fiber 01. The detector arm 13 and the sensor foot 14 have a diameter of 0.5 mm, for example.

[0036] The excitation radiation is guided from the LED chip 03 via the coupling fiber 04, the excitation arm 11 and the sensor foot 14 into the sensor fiber 01, where it excites the fluorescent luminophores 02. The fluorescent radiation emitted by the luminophores runs through the sensor fiber 01, back to the sensor foot 14 of the Y-coupler 12, and then, for the most part, into the detector arm 13. A second colored glass piece 17, which is formed in the form of a waveguide, adjoins the end of the detector arm 13 facing away from the connecting point 16. An optical lens 18 is provided for collimating the fluorescent radiation exiting at the exit surface of the second colored glass piece 17, which is followed by a further filter 19 so as to allow only the fluorescent radiation to pass to a downstream detector 21.

[0037] FIG. 2 shows a modified embodiment of the arrangement for operating the biosensor, which initially largely agrees with the design according to FIG. 1. One difference is that the detector is divided into two sub-detectors 21a and 21b, which are used to detect different wavelengths of the fluorescent radiation. For this purpose, a beam splitter 22 is located downstream from the filter 19 in the radiation direction, which splits the fluorescent radiation into two sub-beams, as a function of the wavelength, which are then fed to the respective sub-detectors 21a, 21b. The second colored glass piece 17 enhances the action of the filter 19.

[0038] FIG. 3 shows, by way of example, the optical beam path in the excitation arm 11, in the detector arm 13, in the region of the connecting point 16 and, above all, in the sensor foot 14. The sensor foot 14 is used for beam deflection and for coupling into or outcoupling from the sensor fiber, while creating the option of a distance of several 100 μm between the sensor foot and the sensor fiber, whereby the positioning is considerably simplified. As is already apparent from FIGS. 1 and 2, the sensor foot 14 is preferably configured to be curved or bent, so as to be easily connectable to the sensor fiber 01 and achieve a beam deflection. The entry surface at the excitation arm 11 and the exit surface at the sensor foot 14 are thus situated at an angle of more than 45°, and preferably of approximately 90°, with respect to one another. The connecting point 16 is particularly preferably optically configured in the manner of a funnel, as is illustrated by the beam path in FIG. 3.

[0039] The funnel-shaped configuration of the connecting point 16 also yields a major advantage for the optical return path, that is, the path of the fluorescent light that is guided from the sensor fiber 01 back to the detector 21. As a result of the shown beam guidance, the optical losses can be minimized, up to the point at which the excitation arm enters into the detector arm. The comparatively low emissions that originate from the fluorescent luminophores 02 can thus be evaluated particularly well at the detector. In this way, a distance of several 100 μm can be implemented between the sensor foot and the sensor fiber, which is of great advantage for designs relevant for practical applications.

[0040] A lens 23 is preferably formed on the side of the sensor foot 14 which faces the sensor fiber 01, and preferably is integrated into the material of the sensor foot. The lens 23 is situated downstream from the toric surface in the direction of the excitation radiation so as to focus the excitation radiation onto the input end face of the sensor fiber 01. The lens can be designed as a spherical or an aspherical lens, and can possibly be non-reflecting.

[0041] Particularly preferably, the numerical aperture that results downstream from the lens 23 at the sensor foot 14 in the direction of the sensor fiber 01 is adapted so as to substantially correspond to the numerical aperture of the sensor fiber.

[0042] According to a preferred embodiment, the diameter of the excitation arm 11 widens in the region of the connecting point 16, as is illustrated based on the beam path in FIG. 3. This widening preferably takes place by a linear, or alternatively by a non-linear, increase in the diameter in the direction of the sensor foot 14. The surface lines of the cone of the widening which results in the longitudinal section can thus be arbitrarily shaped.

[0043] In the region of the curvature of the sensor foot, the beams are deflected, preferably at a toric surface 24, which can be mathematically described as follows:

[00001]$z=\frac{C*y^2}{1+\sqrt{1-\left(C^2*\left(1+CC\right)*y^2\right)}}$

where
the first radius of the toric surface relates to the x axis (radius about an axis in the x direction) (R_about_x; C=1/R_about_x);
CC=conic constant;
the Y coordinate is inserted into the formula as y, yielding the Z coordinate in the case where the toric surface has its origin in point Y=0 and Z=0 and is not rotated counterclockwise by 45°; the second radius of the toric surface relates to the y axis (radius about the axis in the y direction) for the case where the toric surface is not rotated counterclockwise by 45°.

[0044] The reflection occurs at the toric surface, preferably as total reflection. For example, an additional reflecting layer can be applied in this region. This is expedient if the refractive index of the material in the sensor foot is too small, in which case total reflection is not possible. In this case, an additional reflecting layer can be provided on the toric surface.

[0045] This configuration ensures that the excitation radiation extends from the excitation arm 11, across the widening in the region of the connecting point 16 and the toric surface 24, to the lens 23, in the material of the excitation arm. A transition to air or gas, and then into the sensor fiber 01, does not occur until the lens 23.