WO2022174277A1

WO2022174277A1 - Optical unit for measuring fluorescent light

Info

Publication number: WO2022174277A1
Application number: PCT/AT2022/060046
Authority: WO
Inventors: Johannes KROTTMAIER; Volker Ribitsch
Original assignee: Krottmaier Johannes; Volker Ribitsch
Priority date: 2021-02-19
Filing date: 2022-02-18
Publication date: 2022-08-25
Also published as: DE112022001134A5; AT524748A1; AT524748B1

Abstract

In an optical unit (1) for measuring fluorescent light during an optochemical detection of constituents of a fluid, comprising a housing (2) securable to a baseplate (11), at least one light source (3), a fluorescent dye (6) excitable by light from the light source (3), and also a photodetector (4), which detects fluorescent light emitted by the fluorescent dye (6), the substantially ring-shaped housing (2) has the at least one light source (3) and the photodetector (4) in the interior of said housing, the photodetector (4) is surrounded by a shielding element (5), the shielding element (5) and the housing (2) are arranged substantially concentrically with respect to one another, the shielding element (5) and the housing (2) have a substantially mutually corresponding height, and the fluorescent dye (6) is arranged at a top side of the housing (2) facing away from the baseplate (11).

Description

OPTICAL UNIT FOR FLUORESCENT LIGHT MEASUREMENT

The present invention relates to an optical unit for measuring fluorescence light in an optochemical detection of components of a fluid, comprising a housing, at least one light source, a fluorescent dye that can be excited with light from the light source, and a fluorescent light emitted by the fluorescent dye that can be detected ing photodetector. Optical units, such as optochemical sensors, are used to measure a wide variety of fluids, such as gases, liquids or mixtures thereof, both in medical, biological or biochemical areas and in food and other laboratory or industrial areas, in order to detect the presence or to be able to quickly and reliably detect the absence and also the concentration of certain substances with an accuracy of well under 5% uncertainty. Gases whose presence or absence can be determined with such sensors include, for example, oxygen, CO ₂ , but also ozone or ammonia. Furthermore, with such sensors in the medical field, for example by measuring biomolecules or pathogenic substances, certain conclusions can be drawn about processes such as wound healing, the contamination of wounds, the presence or absence of certain pathogens or dgi. be drawn by using them, for example, to measure the pH value, which can be used to draw conclusions about such processes.

However, optochemical sensors can also be used, for example, to check the quality of foodstuffs stored in warehouses, such as fruit or grain. The gas concentration in the storage facility is used to determine whether, for example, rotting or mold problems are occurring or could occur, which can be identified by the emission of specific gases that can be detected with the optical units. The functional principle of optical units such as optochemical sensors is based on the interaction of a light-excitable substance with the analyte to be measured, with the excitable substance being excited with light of a specific suitable wavelength and the molecules after their excitation emit the absorbed energy in the form of fluorescent light when they return to their original state. This fluorescent light is quenched by interactions with the analyte as a function of its concentration. In order to be able to detect such a fluorescence quenching, it is necessary for the fluorescent light to have sufficient intensity on the one hand, and on the other hand, the emitted fluorescent light is reflected or radiated onto a detector, which detects the presence or absence and the concentration of an analyte from the measurement of properties of the light, eg the intensity of the light or the lifetime of the fluorescent light.

The substance to be excited by the incident light, the fluorescent dye, is usually a so-called fluorophore, which is either in direct contact with the substance to be measured during use of an optochemical device or has a cover that is permeable to the substance to be detected - is protected from environmental influences. During operation of such a device, the fluorescent dye is usually irradiated from the side facing away from the substance to be measured, excited and the emitted fluorescent light is picked up by a suitable detector, amplified and measured. This also faces away from the sample to be measured or is positioned in a housing that is protected from the sample to be measured. In particular when using such optical units in the medical or biological field, it is essential that they are dimensioned as small as possible and that they can preferably be used in so-called total microanalysis systems.

The question of the size of such optical units is thus becoming increasingly important, since not only has their area of application drastically expanded in recent times, but attempts are also being made, for example, in small-sized, for example medical devices, in addition to the other necessary devices such as for example in the case of a catheter, which has tools that can be inserted into wounds, optical devices to be able to observe the condition on site or the like, also to be able to directly and without particular effort, for example, detect the presence and absence of analytes to be examined It has proven to be particularly important that such optical units can be miniaturized and designed so small that they can be integrated into microchips or fixed on printed circuit boards, which cannot or cannot be adequately achieved with currently available systems.

If optical units of this type are integrated into chips, it is a regularly occurring problem that the fluorescent light must be separated from the excitation light by means of a spectrometer or by means of optical filters, which has proven to be unsatisfactory since the intensity of the excitation light is usually significantly higher than the intensity of the generated fluorescence light, which is particularly the case with miniaturized systems poses a problem in terms of measurement accuracy, since scattered light can disrupt or falsify the measurement.

Such a device is already known from WO 2015/058221 A2, in which both the excitation light source and the detector are fixed on a base plate arranged parallel to the measuring element, in which the excitation light source and detector are covered by at least part of a material thickness Cover hood are separated from one another and the device is also designed in such a way that excitation light impinges on the measuring element at such an angle that the fluorescence light emitted by the measuring element impinges perpendicularly on a detector.

A high-performance fluorescence sensor has become known from US 2005/0237518 A1, in which a light source and a photodetector are separated by an opaque partition and the light emitted by the light source strikes a fluorescent dye and is directed to the detector by means of internal reflection. Here, the light source and the detector are arranged in one plane, and the substance generating the fluorescent light is separated from both the light source and the detector by arranging a waveguide layer having a certain thickness. In this case, the waveguide layer that is essential for US 2005/237518 is designed in such a way as to minimize an undesired influence of light by the light source, since the light is guided out through the waveguide.

The invention now aims to further simplify the construction of such an optical unit and further miniaturize it, so that it can be used in miniaturized detection devices such as test heads for minimally invasive examinations and. Like. Can be used.

The invention also aims to provide an optical unit with which it is possible to simultaneously excite and detect a wide variety of fluid substances to be measured, so that, for example, the oxygen content of an environment as well as nitrogen oxides or ammonia resulting from the decomposition of substances with one and can be measured and detected with the same sensor.

To solve this problem, the optical unit according to the invention is essentially characterized in that the essentially ring-shaped housing fixed on the base plate has the at least one light source and the photodetector in its interior, that the photodetector is surrounded by a shielding element, that the shielding element and the housing are arranged essentially concentrically with one another, that the shielding element and the housing essentially correspond to one another Having height and that the fluorescent dye is arranged on the top of the housing facing away from the base plate.

Because the essentially ring-shaped housing fixed to the base plate has the at least one light source and the photodetector inside, it is possible to design a particularly compact optical unit that can be arranged, for example, at the tip of a medical test head. Due to the lack of any corners or edged areas on the outer circumference of the unit, such an optical unit can also be used directly in the most sensitive environments such as tissue, for testing sensitive surfaces or the like. In that a photodetector is also surrounded by a shielding element, it is possible to prevent the interfering influence of light from the light source on the photodetector and to ensure that only light emitted by the fluorescent dye impinges on the photodetector or is guided to it. In order to increase this effect even further, the shielding element is designed according to the invention in such a way that the housing and the shielding element are arranged essentially concentrically with one another and have a height which essentially corresponds to one another. This arrangement allows a light source to be arranged in the immediate vicinity of the photodetector, since the concentric arrangement of the housing and shielding element ensures on the one hand that essentially the entire light output of the light source must strike the fluorescent dye upwards and on the other hand through the

Forming the shielding element with essentially the same height as that of the housing ensures that the unintentional impingement of light from the light source directly onto the photodetector, which would represent an interfering light for every optochemical measurement, is avoided or significantly reduced becomes. by applying the fluorescent dye in a known manner to the top of the housing facing away from the base plate, the extremely small design of the optical unit ensures that all of the light emitted by the light source, regardless of whether it is in the inside the housing is reflected once or several times or is guided via a light conductor, in any case on the fluorescent dye ^' meets.

Since the design is such that only the fluorescent dye is applied to the upper side of the housing, it is ensured that only the fluorescent light emitted by the fluorescent dye can impinge on the photodetector. Furthermore, since any reflecting elements are absent in the optical unit, it is further ensured that no excitation light is reflected onto the photodetector. With such a design, it is not only possible to provide extremely compact devices for optical measurement or detection of fluorescent light, but also to further reduce the overall height of the optical unit compared to conventional devices, which on the one hand can increase the measurement accuracy and on the other hand reduces interference. freely a high luminous efficiency of the fluorescent light can be guaranteed. In addition, with such a design of an optical unit, the use of, for example, waveguides or other cost-intensive components or elements can be completely dispensed with, as a result of which an optical unit suitable for extremely cheap mass production is provided and, moreover, a significantly simplified assembly of the optical unity can be achieved.

Since, as corresponds to a development of the invention, the optical unit is designed in such a way that the housing is open on the top side facing away from the carrier and the fluorescent dye is applied to an optical adhesive that fills a free space in the housing, it is possible to provide an optical unit that is particularly easy to produce, in which it is also ensured by filling the free space in the housing with an optical adhesive that no disturbing elements are introduced into the interior of the optical unit and on the other hand a design find on which fluorescent dye can be applied directly and thus the light intensity of the light source that hits this fluorescent dye can be maximized due to the lack of a separate carrier or an air gap.

By, as corresponds to another or supplementary development of the invention, that the housing is closed on the top side facing away from the base plate with a cover that is permeable to excitation light emitted by the light source and fluorescent light to be detected and that the cover is seamlessly connected to the If the free space in the housing forms an optical adhesive that falls out, a more stable construction of the optical unit is provided than that in which the free space is filled with an optical adhesive . The fact that only fluorescent light emitted by the fluorescent dye reaches the interior of the optical unit, where the photodetector is arranged, and not, for example, scattered light from the light source or from an external light source can enter, makes it possible to significantly increase the measurement accuracy of the optical unit. By allowing the cover to seamlessly connect with the free space in the Optical adhesive that fills the housing further ensures that any penetration of scattered light or desired reflections are avoided.

For further miniaturization of the optical unit, the invention is further developed such that the fluorescent dye is applied directly to the cover that is permeable to the excitation light and the fluorescent light to be detected. With such a design, it is possible to provide an extremely thin cover for the optical unit compared to conventional optical units and thus miniaturize it even further. Furthermore, with such a design, it is possible to maximize the light yield of both the light source and the fluorescent dye, since the number of layers that are arranged between the respective light sources and the fluorescent dye on the one hand and the fluorescent dye and the photodetector on the other are also minimized.

In order to optimize the light output, the optical unit, as corresponds to a development of the invention, is designed in such a way that the cover extends to a lower edge of the housing and that a side wall of the cover is designed with a mirror finish.

By, as corresponds to a development of the invention, the optical unit is further developed in such a way that the housing is designed as a light guide and that the at least one light source is arranged covered by a wall part of the housing, it is possible to form a unit in which the at least one light source is arranged covered by a wall part of the housing and thus the emission of scattered light to the inside as well as to the outside of the optical unit is undoubtedly avoided by the arrangement of the wall part and the light source. Since all of the light from the at least one light source is transported through this light guide to the top of the optical unit and is available there for exciting the fluorescent dye, the light yield is maximized and a light signal that is easy to detect and unaffected by external light influences is achieved ! for detection in the photodetector. Needless to say, the housing can be designed as a circular ring, ellipse or other shape in a plan view, or the light sources can also be arranged at the corners of a polygon and can be covered by columnar parts of the housing . Finally, there is no need to state that not all light sources have to be identical to one another, but that the light sources can be selected in such a way that different excitation wavelengths are emitted in order to be able to detect different analytes. By, as corresponds to a development of the invention, the optical unit is designed so that the housing is designed as a hollow body closed on one side, that on the closed top of the hollow body a substantially funnel-shaped, the closed top of the hollow body with the Shielding element of the photodetector connecting wall element is arranged, it is possible to direct any fluorescent light exclusively onto the photodetector, which ensures that light is not reflected into the interior of the optical unit, especially in that area that is not bw from the photodetector. is occupied by its shielding element. With such a design, it is thus possible to safely and reliably conduct even weak fluorescent light signals into the photodetector, since it is ensured that these signals are free from the influence of light.

If, as is desired in some cases, only certain wavelengths of the fluorescence light are to be directed to the photodetector, the invention is further developed such that an optical filter is also arranged between the photodetector and the fluorescence dye.

By, as corresponds to a development of the invention, the design is such that a plurality of light sources, which may emit light with different wavelengths, are arranged in the housing or covered by a wall part of the housing and that between each of the plurality of Light sources and shielding elements are arranged ^, it is possible to provide an optical unit with which it is possible to excite _, stimulate and measure different analytes with one and the same optical unit, always provided that the fluids to be measured and the fluorescent dye can be excited by the different wavelengths, it also being possible for several or different fluorescent dyes to be arranged on the upper side of the optical unit. The type and form of the arrangement is arbitrary.

Since the design is such that shielding elements are arranged between each of a plurality of light sources, it is simultaneously avoided that excitation light possibly emitted by different light sources can propagate unhindered inside an optical unit and thus light with different wavelengths Excitation wave lengths hit a sample to be measured containing various excitable substances, so that fluorescent light may be extinguished before it is detected. In order to avoid this, shielding elements are arranged which prevent an unintentional propagation of excitation light. By further arranging shielding elements between each individual one of the plurality of light sources, it is ensured that that only the excitation light with precisely defined wavelengths hits the fluorescent dye.

This problem of the simultaneous excitation of the sample to be measured by a plurality of light sources of different wavelengths can be avoided by being able to control each light source selectively, with the result that a configuration which does not require any shielding elements can be achieved.

In order to ensure that, especially when used in practice or in direct contact of the optical unit with substances to be measured, there is no damage to the optical unit, in particular the fluorescent dye of the same, the invention is further developed to the effect that the fluorescent dye with covered by a light protection membrane and/or an optical filter. The light-protection membrane and/or the optical filter prevent the access of external light to the fluorescent dye and the access of excitation light to the photodetector. To avoid damage to the fluorescent dye, the outer light-protection membrane is essentially designed such that the outer light-protection membrane has a pore size of 0.1 μm to 100 μm, preferably 1 μm to 20 μm. If the outer light protection membrane has pore sizes between 0.1 μm and 100 μm, preferably between 1 μm and 20 μm, it is ensured that damage to the fluorescent dye is prevented, any ingress of dust, for example, is avoided and at the same time it is ensured that substances to be detected can interact with the fluorescent dye.

For a particularly compact optical element or an optical unit, the invention is further developed such that the base plate is a carrier plate for electronic components. With such a construction it is possible to provide optical units which can be parts of an integrated circuit or can be directly connected to evaluation units or are integrated into them.

The fact that the components, namely the photodetector and the microprocessor, are positioned in direct or very small distance from one another, or a microprocessor with an integrated photodetector is used, enables signal evaluation without a preamplifier. The invention is explained in more detail below with reference to embodiments shown in the drawing _:

Fig. Figure 1 is a sectional side view of a first embodiment of an optical unit according to the invention.

FIG. 2 shows a plan view of the optical unit according to FIG. 1,

3, 4 and 5 further embodiments of the optical unit according to the invention, and

Fig. 6 shows a more detailed sectional view of a variant of an optical unit according to Fig. 1, in detail an optical unit 1 is constructed from a housing 2, in which housing 2 at least one light source 3 is contained, a photodetector 4 is provided and a shielding element 5. The shielding element 5 is designed in such a way that its height essentially corresponds to that of the photodetector 4, so that no light emitted by the light source or the photodiode 3 can impinge on the photodetector 4 without this light first being in contact with the light on the Top applied fluorescent dye 6 can reach. In the illustration according to FIG. 1, the interior of the optical unit 1 is filled with an optical adhesive 7, on the upper side of which the fluorescent dye 6 is applied directly. Finally, an optical filter 8 is also arranged on top of the photodetector 4 in the embodiment according to FIG.

According to an embodiment variant of the optical unit 1, a glass element can be inserted into the optical adhesive 7 on the upper side of the optical unit 1, which glass element carries the fluorescent dye on the outside and is mirrored on the outer ring. Such a design contributes to a further improvement in the fluorescent light yield.

From FIG. 2, which shows a plan view of the design of the optical unit 1 from FIG. which are arranged in such a way that they shield the individual light sources 3 from one another. With this design, it is possible, for example, to arrange two light sources 3 inside the optical unit 1, which can each emit different excitation wavelengths. Surrounding the photodetector 4 is a shielding element 5, which is designed as a ring-shaped shielding element 5 in the embodiment of FIGS. In addition, a fluorescent dye is not shown in FIG. 2, which otherwise corresponds to that of FIG. 1, since otherwise a view into the interior of the optical unit 1 would be covered.

Fig. 3, in which the reference numerals from Figs. 1 and 2 are retained as far as possible, shows another embodiment of the optical unit 1 of Fig. 1.

In this embodiment, the housing 2 is designed in such a way that it rests on the light sources 3 . In this configuration, the housing 2 is in the form of an optical waveguide which is permeable to the light emitted by the light sources 3 and guides it to the fluorescent dye on the upper side. In addition to the fact that the housing 2 is designed as an optical waveguide, it is different from the illustration in Fig.

1 designed as a closed housing so that it covers the entire interior of the optical unit 1. A fluorescent dye 6 is applied to the top of the housing 2 . In the representation of FIG. 3, an optical filter 8 is provided as well as the shielding element 5. The shielding element 5 is used in the embodiment according to FIG

2 does not cover the entire cross section of the light source 3 and thus light is unintentionally emitted into the interior of the optical unit 1, in particular at

Mass production of such optical units 1 can lead to such an imprecise positioning of the housing 2 on the light source 3, so that in order to ensure trouble-free functioning of the optical unit 1, the shielding element 5 is provided for safety reasons.

In contrast to the embodiment in FIG. 1, however, in the embodiment in FIG. 3 it is not necessary for the cavity of the optical unit 1 to be filled with an optical adhesive 7, since the housing as such is designed to be closed. However, the shielding element 5 can also be brought forward to the underside of the closed housing 2 and only this shielding element 5 can be filled with an optical adhesive. This ensures that the air gap between the photodetector 4 and the closed housing 2 is minimized, which in turn results in better fluorescent light expansion.

The design according to FIG. 4 essentially corresponds to that of FIG. ter-shaped guide element 10 is provided, which directs the fluorescent light from the fluorescent dye 6 directly to the photodetector 4 or the optical filter 8 .

With regard to the arrangement of the light sources, FIG. 5 corresponds to FIG. 1, the housing 2 in FIG. 5 also being designed as a closed housing, on the upper side of which the fluorescent dye 6 is applied. With such a closed housing, at least that part of the housing 2 that is intended as a carrier element for the fluorescent dye 8, i.e. the cover 2a for the fluorescent light can be designed to be permeable. In order to avoid unintentional exposure of the photodetector 4 to light from the light sources 3 in this variant as well, the photodetector 4 must in turn be surrounded by a shielding element 5 .

FIG. 6 corresponds to the representation of FIG. 1, in which a base plate 11 is additionally provided, which can be an electronic circuit board. In the representation of FIG. 6, the housing 2 and the shielding element 5 are made of one and the same material and both elements are not light-conducting, as described in connection with FIG. In the representation according to FIG. 8, light sources 3 are each accommodated in a base 12 which is soldered directly onto the electronic circuit board 11 . In this variant, the entire cavity of the optical unit 1 is in turn filled with an optical sealing compound or an optical adhesive 7 , which optical adhesive or optical sealing compound 7 serves as a carrier for the fluorescent dye 6 .

It goes without saying that the optical unit 1 according to the invention can also be designed in a large number of other variants and that in particular the shielding element 5 in particular in those variants of the optical unit 1 according to the invention in which the light source is directly connected to the housing 2 is covered and this housing 2 also completely overlaps the light source, can theoretically be omitted, but should be retained for safety reasons, in particular due to inaccuracies that occur again and again in mass production, and can advantageously be brought forward to the lower edge of the housing.

However, all other constructions or configurations are conceivable and the advantage of the optical unit according to the invention is that it is extremely compact and that, in contrast to known optical units, it does not require the fluorescent light to be directed perpendicularly must impinge on the photodetector, since it is able to capture and reliably detect the smallest amounts of fluorescent light due to the miniaturization and the extremely short distance between the photodetector and the fluorescent dye 6 . With such a device, it is not only possible to provide an inexpensive component that is easy to assemble, but such an optical unit can, for example, be used directly for long-term monitoring of certain foods, such as fruit, baby food, sausages or the like. be used, in particular used wherever, for example, goods are packaged under reduced O ₂ concentration. This is particularly so because the optical unit does not contain any sensitive or complex components.

Furthermore, as has also been stated, a plurality of different light sources can be arranged in one and the same optical unit in order to apply different excitation light wavelengths to the fluorescent dye(s) 6 . It goes without saying that if one and the same fluorescent dye 6 is not excitable with several different light wavelengths, either multilayer arrangements of the fluorescent dye or segmented arrangements of different fluorescent dyes must of course be provided. In addition, combinations of exposed light sources 3 arranged inside the optical unit 1 and light sources 3 which are covered by the housing 2 are also encompassed by the present invention.

Claims

patent claims

1. Optical unit (1) for measuring fluorescence light in an optochemical detection of components of a fluid, comprising a housing (2) that can be fixed with a base plate (11), at least one light source (3), one with light from the light source (3) excitable fluorescent dye (6) and a fluorescence light-detecting photodetector (4) emitted by the fluorescent dye (6), characterized in that the essentially ring-shaped housing (2) contains the at least one light source (3 ) and the photodetector (4), that the photodetector (4) is surrounded by a shielding element (5), that the shielding element (5) and the housing (2) are arranged essentially concentrically with one another, that the shielding element (5 ) and the housing (2) have a height that essentially corresponds to one another and that the fluorescent dye (6) is arranged on a top side of the housing (2) facing away from the base plate (11) i st

2. Optical unit (1) according to claim 1, characterized in that the housing (2) is open on the top side facing away from the carrier and that the fluorescent dye (6) fills out a free space in the housing (2). optical adhesive (7) is applied,

3. The optical unit (1) according to claim 1, characterized in that the housing (2) on the top side facing away from the base plate (11) is provided with a cover ( 2a) is closed and that the cover (2a) forms a seamless connection with the optical adhesive (7) filling the free space in the housing (2).

4. Optical unit (1) according to claim 3, characterized in that the fluorescent dye (6) is applied to the cover (2a) which is transparent to the excitation light and the fluorescent light to be detected.

5. Optical unit (1) according to claim 3 or 4, characterized in that the cover (2a) extends up to a lower edge of the housing (2) and that a side wall of the cover (2a) is mirrored.

6. Optical unit (1) according to claim 3, 4 or 5, characterized in that the housing

(2) is designed as a light guide and that the at least one light source (3) is arranged covered by a wall part of the housing (2).

7. Optical unit (1) according to one of Claims 1 to 6, characterized in that an optical filter (8) is also arranged between the photodetector (4) and the fluorescent dye (6),

8. Optical unit (1) according to one of claims 1 to 7, characterized in that the housing (2) is designed as a hollow body closed on one side, that on the closed top of the hollow body a substantially funnel-shaped, the closed top of the hollow body with the The wall element connecting the shielding element (5) of the photodetector (4) is arranged,

9. Optical unit (1) according to any one of claims 1 to 8, characterized in that a plurality of light sources (3) optionally emitting light with different wavelengths from one another in the housing (2) or from a wall part of the housing (2) are arranged covered and that between each of the plurality of light sources (3) shielding elements (5) are arranged.

10. Optical unit (1) according to one of claims 1 to 9, characterized in that the fluorescent dye (6) is/are covered with a light-protection membrane and/or an optical filter.

11. Optical unit (1) according to claim 10, characterized in that the outer light protection membrane is designed with a pore size of 0.1 μm to 100 μm, preferably 1 μm to 20 μm.

12. Optical unit (1) according to any one of claims 1 to 11, characterized in that the base plate (11) is a carrier plate for electronic components.