DE102021133357A1 - Sensor element, sensor system and method for manufacturing the sensor element - Google Patents

Abstract

The invention relates to a sensor element (10) for detecting an analyte, comprising: - a light guide (20) which extends along an axis (A) and a first end (21), a second end (22) and a between the first end (21) and the second end (22) extending lateral surface (23), wherein the light guide (20) is suitable for introducing a stimulation light (S) into the light guide (20) at the first end (21), - a Functional layer (30), which is arranged on the light guide (20) so that the lateral surface (23) is covered by the functional layer (30), the functional layer (30) being suitable for being stimulated by the stimulation light (S). to emit a luminescent light (L).

Description

The invention relates to a sensor element, a sensor system and a method for producing the sensor element.

In analytical measurement technology, especially in the field of water management, environmental analysis, in the industrial sector, e.g. in food technology, biotechnology and pharmacy, as well as for a wide variety of laboratory applications, measured variables such as the pH value, conductivity or the concentration of analytes, such as ions or dissolved gases in a gaseous or liquid measuring medium is of great importance. These measured variables can be recorded and/or monitored, for example, by means of optochemical or electrochemical sensors.

Optochemical sensors have an optochemical substrate which, when stimulated with excitation radiation, emits a mostly luminescent response signal. The signal properties of the response signal can be influenced by certain target analytes. If a target analyte is present in the measurement medium, the response signal of the optochemical sensor is changed, which indicates the concentration of the target analyte in the measurement medium.

A problem with optochemical substrates is the usually low quantum yield and/or extinction coefficient, which leads to relatively weak response signals and thus to a suboptimal signal-to-noise ratio. This in turn harbors the risk of unreliable measurement signals. In order to increase the intensity of the response signals and thus achieve increased measurement reliability, it is possible to increase the intensity of the stimulation signal. However, this inevitably leads to a shortened lifetime of the optochemical substrate and increased power consumption. However, increased energy consumption is particularly disadvantageous if the sensor with the sensor element is to be used in a potentially explosive area, since specific energy regulations with strict energy limits apply there.

1. a) eine zu geringe Intensität des Sensorspots aufgrund von einer zu geringen Farbstoffquantenausbeute, eines zu geringen spezifischen Extinktionskoeffizienten des Farbstoffes, einer zu geringen Farbstoffkonzentration (besonders problematisch bei z.B. pH-Sensoren, Biosensoren und Algensensoren);
2. b) Absorptionsverluste durch zu dicke Sensorschichten und dadurch bedingt zu langsame Ansprechzeiten des Sensors (z.B. Farbstoff gelöst in Fluoropolymer wie HyflonAD oder TeflonAF).

Other known problems with optochemical substrates are:

1. a) too low an intensity of the sensor spot due to too low a dye quantum yield, too low a specific extinction coefficient of the dye, too low a dye concentration (particularly problematic with pH sensors, biosensors and algae sensors, for example);
2. b) Absorption losses due to sensor layers that are too thick and the resulting sensor response times that are too slow (e.g. dye dissolved in fluoropolymer such as HyflonAD or TeflonAF).

It is therefore an object of the invention to provide a sensor element which makes it possible to maximize reliability and sensitivity while at the same time minimizing the energy consumption for operating the sensor element.

This object is achieved according to the invention by the sensor element according to claim 1.

• - einen Lichtleiter, welcher sich entlang einer Achse erstreckt und ein erstes Ende, ein zweites Ende sowie eine sich zwischen dem ersten Ende und dem zweiten Ende erstreckende Mantelfläche aufweist,

wobei der Lichtleiter dazu geeignet ist, am ersten Ende ein Stimulationslicht in den Lichtleiter einzuleiten,

• - eine Funktionsschicht, welche auf dem Lichtleiter angeordnet ist, so dass die Mantelfläche von der Funktionsschicht bedeckt ist, wobei die Funktionsschicht dazu geeignet ist, durch das Stimulationslicht stimuliert zu werden, um ein Lumineszenzlicht zu emittieren.

The sensor element according to the invention for detecting an analyte, comprising:

• - a light guide which extends along an axis and has a first end, a second end and a lateral surface extending between the first end and the second end,

wherein the light guide is suitable for introducing a stimulation light into the light guide at the first end,

• - a functional layer which is arranged on the light guide so that the lateral surface is covered by the functional layer, the functional layer being suitable for being stimulated by the stimulation light in order to emit a luminescent light.

The sensor element according to the invention makes it possible for the signal intensity of the luminescence light emitted by the functional layer to be maximized. At the same time, the sensor element enables the intensity of the stimulation light to be minimized, which leads to a minimization of energy. The sensor element is therefore particularly suitable for use in sensors which are used in potentially explosive areas in which there are strict energy limits for sensors. Likewise, thanks to the possible low stimulation light, a reduced long-term drift is achieved with a sufficient layer thickness of the measured values determined using the sensor element. The reliability of the measurement results determined by the sensor element is thus maximized by the sensor element, the sensitivity of relevant analytes is maximized and the energy consumption of a sensor with the sensor element is minimized. Another advantage is that minimal material quantity is required to create the functional layer. A sensor element is thus made available which has an optimal response time and minimal material consumption for the functional view.

According to one embodiment of the invention, the functional layer is a gas-permeable one and/or covered with a water-permeable membrane layer.

According to a further embodiment of the invention, the gas-permeable and/or water-permeable membrane layer is covered by a gas-permeable and/or water-permeable protective layer.

According to one embodiment of the invention, a reflection layer is arranged at the second end, and the reflection layer is suitable for reflecting the stimulation light.

According to one embodiment of the invention, the light guide has a refractive index greater than the refractive index of the functional layer.

According to one embodiment of the invention, a reflection layer and/or an optical insulation layer is applied to the functional layer.

According to an embodiment of the invention, the light guide has a cylindrical shape, a truncated cone shape, a cone shape, a pyramidal shape or a tetragonal shape.

The above object is also achieved by a sensor system according to claim 8.

• - mindestens ein erfindungsgemäßes Sensorelement,
• - eine Lichtquelle, welche dazu geeignet ist, ein Stimulationslicht zu emittieren und derart angeordnet ist, dass das Stimulationslicht am ersten Ende des Lichtleiters in den Lichtleiter einleitbar ist,
• - einen Detektor, welcher dazu geeignet ist, ein Lumineszenzlicht zu detektieren,
• - eine Steuereinheit, welche mit der Lichtquelle und dem Detektor verbunden ist, und dazu geeignet ist, eine Emission des Stimulationslichts der Lichtquelle zu steuern und ein von dem Detektor detektiertes Lumineszenzlicht auszuwerten.

The sensor system according to the invention includes:

• - at least one sensor element according to the invention,
• - a light source which is suitable for emitting a stimulation light and is arranged in such a way that the stimulation light can be introduced into the light guide at the first end of the light guide,
• - a detector which is suitable for detecting a luminescent light,
• - a control unit which is connected to the light source and the detector and is suitable for controlling an emission of the stimulation light of the light source and for evaluating a luminescence light detected by the detector.

According to one embodiment of the invention, the light source and the detector are each connected to the first end of the light guide via an optical fiber.

The above object is also achieved by a method for manufacturing a sensor element according to claim 10.

• - Bereitstellen eines Lichtleiterrohlings,
• - Ausbilden mindestens eines Lichtleiters mittels einem Laserverfahren oder einem spanenden Materialabtragungsverfahren,
• - Auftragen einer Funktionsschicht auf den mindestens einen Lichtleiter mittels einem Eintauch-Verfahren, Spraycoating-Verfahren, Spincoating-Verfahren oder Inkjet-Verfahen.

The method according to the invention comprises the following steps:

• - Provision of a light guide blank,
• - Forming at least one light guide by means of a laser process or a material removal process,
• - Application of a functional layer to the at least one light guide by means of an immersion method, spray coating method, spin coating method or inkjet method.

The above object is also achieved by a method for producing a sensor element according to claim 11.

• - Ausbilden mindestens eines Lichtleiters mittels einem additiven Materialauftragungsverfahren, insbesondere einem 3D-Druck-Verfahren,
• - Auftragen einer Funktionsschicht auf den mindestens einen Lichtleiter mittels einem Eintauch-Verfahren, Spraycoating-Verfahren, Spincoating-Verfahren oder Inkjet-Verfahen.

The method according to the invention comprises the following steps:

• - Forming at least one light guide by means of an additive material application process, in particular a 3D printing process,
• - Application of a functional layer to the at least one light guide by means of an immersion method, spray coating method, spin coating method or inkjet method.

• - 1: eine schematische Darstellung eines erfindungsgemäßen Sensorsystems mit einem erfindungsgemäßen Sensorelement,
• - 2: eine weitere schematische Schnittzeichnung eines erfindungsgemäßen Sensorsystems und eines erfindungsgemäßen Sensorelements,
• - 3: eine schematische Darstellung eines Schritts des erfindungsgemäßen Herstellungsverfahrens des erfindungsgemäßen Sensorelements,
• - 4: einen auf den in 3 dargestellten Schritt nachfolgenden Schritt,
• - 5: einen auf den in 4 dargestellten Schritt nachfolgenden Schritt,
• - 6: einen auf den in 5 dargestellten Schritt nachfolgenden Schritt,
• - 7: einen auf den in 6 dargestellten Schritt nachfolgenden Schritt,
• - 8: einen auf den in 6 dargestellten Schritt nachfolgenden alternativen Schritt,
• - 9: eine alternative Ausführungsform eines Sensorelements,
• - 10: eine alternative Ausführungsform des Sensorsystems aus 2.

The invention is explained in more detail with reference to the following description of the figures. Show it:

• - 1 : a schematic representation of a sensor system according to the invention with a sensor element according to the invention,
• - 2 : another schematic sectional drawing of a sensor system according to the invention and a sensor element according to the invention,
• - 3 : a schematic representation of a step of the manufacturing method according to the invention of the sensor element according to the invention,
• - 4 : one on the in 3 shown step following step,
• - 5 : one on the in 4 shown step following step,
• - 6 : one on the in 5 shown step following step,
• - 7 : one on the in 6 shown step following step,
• - 8th : one on the in 6 shown step subsequent alternative step,
• - 9 : an alternative embodiment of a sensor element,
• - 10 : an alternative embodiment of the sensor system 2 .

1 shows a sensor system 1 according to the invention with at least one sensor element 10, a light source 2, a detector 3 and a control unit 4.

2 shows the sensor system 1 and sensor element 10 according to the invention for detecting an analyte. The light source 2 and the detector 3 are also shown schematically in 2 shown, which will be discussed in detail later.

The sensor element 10 is suitable for being exposed to a measurement medium M in which a specific analyte N is present. The analyte N is a specific molecule, such as oxygen, or is a specific ion, such as a potassium ion, a sodium ion, or a hydrogen ion.

The sensor element 10 comprises a light guide 20 and a functional layer 30. The sensor element 10 extends along an axis A and has a first end 21, a second end 22 and a lateral surface 23 extending between the first end 21 and the second end 22. The lateral surface 23 connects the first end 21 and the second end 22.

The light guide 20 is suitable for introducing a stimulation light S into the light guide 20 at the first end 21 . The light guide 20 is made, for example, from glass, glass ceramic, silicate, sapphire, polymer, polycarbonate, PET, PEN, PVDF, Teflon, or hybrid materials such as ormosile and derivatives thereof. Hydrophilized surfaces of these materials are also possible for use of the light guide 20. The light guide 20 has, for example, a cylindrical shape, a truncated cone shape, a cone shape, a pyramidal shape, a rhombic shape, or a tetragonal shape (see FIG 9 ). A surface-to-volume ratio of the light guide 20 is preferably greater than 3, more preferably greater than 5, and most preferably greater than 10. The light guide 20 has, for example, a refractive index between 1.3 and 1.7. The refractive index of the light guide 20 is preferably greater than the refractive index of the functional layer 30. According to one embodiment, the light guide 20 is designed as a type of side light fiber. In other words, the stimulation light S guided in the core of the light guide 20 is not only guided along the axis A, but is also specifically emitted laterally into the functional layer 30 . The lateral surface 23 of the light guide 20 is preferably designed to be rough or porous, for example by means of a sandblasting process, so that the adhesion of the functional layer 30 is optimal and/or that the stimulation light S is suitable for being scattered into the functional layer 30. If the lateral surface 23 is porous, the functional layer 30 extends at least partially into the light guide 20. In other words, the functional layer 30 fills the pores of the surface of the light guide 20.

The functional layer 30 is arranged on the light guide 20 such that the lateral surface 23 is covered by the functional layer 30 . The functional layer 30 is suitable for being stimulated by the stimulation light S in order to introduce a luminescence light L into the light guide 20, so that the luminescence light L can be led out at the first end 21 (see FIG 2 - 8th ). The functional layer 30 has an indicator dye which emits a luminescent light L when stimulated with the stimulation light S, preferably at a specific wavelength, for example 300 nm-1500 nm, preferably at the wavelength of 350 nm-2000 nm. Depending on the concentration of the analyte N in the measurement medium M, the properties (intensity, phase, etc.) of the luminescence light L are influenced (so-called quenching; or an intensity increase). The luminescent light L emitted by the indicator dye is preferably fluorescent. According to one embodiment, the functional layer 30 also has a reference dye which emits a luminescence light L independently of the concentration of an analyte N in the measurement medium. Thus, in this embodiment, part of the luminescence light L is generated by the reference dye. The portion of the luminescent light L that is generated by the reference dye is phosphorescent. A sensor element 10 of this embodiment is suitable for use in so-called dual lifetime referencing. The functional layer preferably has a thickness of 0.01 μm-10 μm, particularly preferably 0.1-5 μm.

In the following, reflection is understood to mean: scattering (e.g. by means of an oxide coating), mirroring (e.g. by means of a metal coating), total reflection (layer has a lower refractive index than the layer in front of the light path).

If the reflective layer 60 is arranged at the second end 22 of the light guide 20, then scattering or reflection takes place at the reflective layer 60 (see FIG 4 - 8th ).

If the reflection layer 60' is arranged laterally to the light guide 20, i.e. along the axis A, then total reflection, scattering or reflection takes place at the reflection layer 60' (see Fig 10 ). In this embodiment, the reflection layer 60` is optionally formed in multiple layers, with the refractive index of the respective layers decreasing the more the layers are removed from the light guide 20.

Alternatively, in the case of thin layers and a porous structure (so-called ter "Leaky Mode Waveguide") can also be applied directly to the indicator dye. Ideally, the reflection layer 60 is applied to the end of the fiber, that is to say to the second end 22 .

According to one embodiment, the functional layer 30 is covered by a gas-permeable and/or water-permeable membrane layer 40 (see FIG 6 ).

According to one embodiment, the gas-permeable and/or water-permeable membrane layer 40 is covered by a gas-permeable and/or water-permeable protective layer 50 (see FIG 7 - 8th ). The protective layer 50 also has, for example, optically insulating properties.

According to an embodiment that is compatible with all embodiments, a reflection layer 60 is arranged at the second end 22 . The reflection layer 60 is suitable for reflecting the stimulation light S (see FIG 3 - 8th ). The reflective layer 60 is made of silver or another mirror-like material, for example. The reflection layer 60 preferably has optically isolating properties. Optically isolating is understood to mean that the reflective layer 60 cannot be traversed by, for example, stimulation light S or luminescence light L.

All layers arranged above the functional layer 30 preferably have a thickness of less than 10 μm, preferably between 0.01-5 μm, particularly preferably between 0.1-2 μm.

The light source 2 is suitable for emitting a stimulation light S. The stimulation light S preferably has a wavelength between 300 nm and 1500 nm, particularly preferably between 450-900 μm. The wavelength is selected depending on the area of application of the sensor element, i.e. depending on the medium to be measured. The light source 2 is arranged in such a way that the stimulation light S can be introduced into the light guide 20 at the first end 21 of the light guide 20 . For example, the light source 2 is connected to the first end 21 of the light guide 20 by means of an optical fiber 5 (see FIG 1 ). The stimulation light S is preferably introduced into the light guide 20 in such a way that the stimulation light S propagates in the light guide 20 by reflection and/or total reflection. For example, the stimulation light S exits the light guide 20 again at the first end 21 .

The detector 3 is suitable for detecting a luminescence light L and is arranged in such a way that a luminescence light L exiting at the first end 21 of the light guide 20 can be detected by the detector 3 . For example, the detector 3 is connected to the first end 21 of the light guide 20 by means of an optical fiber 5 (see FIG 1 ). If the stimulation light S exits the light guide 20 again and also falls on the detector 3, the detector 3 has a filter, for example, in order to filter the stimulation light S but to detect the luminescence light L. The detector 3 is suitable, for example, for only detecting light in a restricted wavelength range, in particular the wavelength range which corresponds to the luminescence light L. FIG.

The control unit 4 is connected to the light source 2 and the detector 3 . The control unit 4 is suitable for controlling an emission of the stimulation light S from the light source 2 and for evaluating a luminescence light L detected by the detector 3 .

10 shows a further embodiment of the sensor system 1, which is based on the so-called transmitted light variant. The difference to the in 1 Sensor system 1 shown is that the light guide 20 is free of coatings at the second end 22, so that the stimulation light S and luminescence light L is suitable for exiting at the second end 22 of the light guide 20. In this embodiment, the detector 3 is arranged at the second end 22 . For example, the detector 3 is provided with a filter 6 so that only the luminescence light L passes through the filter 6. Optionally, the reflection layer 60 ′ is arranged on the functional layer 30 so that luminescence light L emerging from the functional layer 30 is reflected back into the light guide 20 . The reflective layer 60' has, for example, a lower refractive index than the functional layer 30, or comprises a reflective metal such as silver, chromium, etc., or comprises a light-scattering material, for example metal oxides such as titanium oxide.

The sensor system 1 can be designed in different variants, for example.

• Die Funktionsschicht 30 weist den Indikatorfarbstoff auf und ist auf der Oberfläche des Lichtleiters 20 angeordnet. Die Reflexionsschicht 60 ist am Faserende angeordnet. Die Zwischenräume zwischen den einzelnen Sensorelementen 10 sind mit permeablen Füllmaterial (Silikon+Pigmentmaterial) gefüllt. Der Indikatorfarbstoff ist direkt in Fluoropolymere wie Teflon AF, Hyflon AD etc. gelöst, was das Sensorsystem 1 besonders für Anwendungen wie gelöst Sauerstoffmessungen und für die Verwendung als Biosensor eignen lässt. Die Anregungswellenlänge des Stimulationslichts S liegt hier bei 450 - 1000nm (Ausnahmen möglich bis 1500nm).

Option A:

• The functional layer 30 has the indicator dye and is arranged on the surface of the light guide 20 . The reflection layer 60 is arranged at the end of the fiber. The spaces between the individual sensor elements 10 are filled with permeable filling material (silicone+pigment material). The indicator dye is dissolved directly in fluoropolymers such as Teflon AF, Hyflon AD, etc., which makes the sensor system 1 particularly suitable for applications such as dissolved oxygen measurements and for use as a biosensor. The excitation wavelength of the stimulation light S is 450 - 1000 nm (exceptions possible up to 1500 nm).

• Die Funktionsschicht 30 weist den Referenzfarbstoff auf und ist auf der Oberfläche des Lichtleiters 20 angeordnet. Die Reflexionsschicht 60 ist am Faserende angeordnet. Die Zwischenräume zwischen den einzelnen Sensorelementen 10 sind ohne Füllmaterial oder aber mit wasserdurchlässigem Material (Hydrogele, Polyurethane, Polysaccharide, Cellulosederivate, Siloxane, Aerogele, Solgel) versehen, was eine Verwendung des Sensorsystems besonders für Anwendungen wie Algenmessung und Öl-Messung ermöglicht. Die Anregungswellenlänge des Stimulationslichts S liegt bei: 250-550nm.

Variant B:

• The functional layer 30 has the reference dye and is arranged on the surface of the light guide 20 . The reflection layer 60 is arranged at the end of the fiber. The spaces between the individual sensor elements 10 are provided without filling material or with water-permeable material (hydrogels, polyurethanes, polysaccharides, cellulose derivatives, siloxanes, aerogels, solgel), which allows the sensor system to be used in particular for applications such as measuring algae and oil. The excitation wavelength of the stimulation light S is: 250-550nm.

• Die Funktionsschicht 30 weist den Indikatorfarbstoff und den Referenzfarbstoff auf und ist auf der Oberfläche des Lichtleiters 20 angeordnet. Die Reflexionsschicht 60 ist am Faserende angeordnet. Die Zwischenräume zwischen den einzelenen Sensorelementen 10 sind mit wasserdurchlässigem Material (Hydrogel, Hydrogele, Polyurethane, Polysaccharide, Cellulosederivate Siloxane, Aerogele, Solgel) gefüllt, was eine Eignung des Sensorsystems 1 besonders für pH-Messungen und eine Verwendung als Biosensor ermöglicht. Die Anregungswellenlänge des Stimulationslichts S liegt bei 450-1000 nm (Ausnahmen möglich bis 1500nm).

Variant C:

• The functional layer 30 has the indicator dye and the reference dye and is arranged on the surface of the light guide 20 . The reflection layer 60 is arranged at the end of the fiber. The spaces between the individual sensor elements 10 are filled with water-permeable material (hydrogel, hydrogels, polyurethanes, polysaccharides, cellulose derivatives, siloxanes, aerogels, solgel), which makes the sensor system 1 particularly suitable for pH measurements and use as a biosensor. The excitation wavelength of the stimulation light S is 450-1000 nm (exceptions possible up to 1500 nm).

The method for producing the sensor element 10 is described below.

According to a first implicit step, a light guide blank is provided (in 3 shown dashed).

At least one light guide 20 is then formed by means of a laser process or a material-removing process. A plurality of light guides 20 is preferably formed (see FIG 3 ). A base of the light guide blank, a so-called substrate base, is preferably retained for optimum stability of the light guide 20 or the light guide 20 (see FIG 3 ). The light guides 20 are preferably perpendicular to the substrate floor.

The functional layer 30 is then applied to the at least one light guide 20 by means of an immersion method, spray coating method, spin coating method, inkjet method, a combination of these aforementioned methods, or another suitable method (see 5 ).

If the immersion method is used, for example by means of an immersion bath, this is ideally followed by a step of removing excess material from the functional layer 30 from the sensor element 10, so that when a plurality of light guides 20 have each been coated with the functional layer 30, the respective functional layers 30 do not touch along axis A. In other words, after the functional layer 30 has been applied, there is still a gap between the various sensor elements 10 . This enables the analytes N to be measured to be apt to come into contact with the functional layers 30 . Excess material is removed, for example, with the help of a centrifugal process. This enables a homogeneous layer thickness of the functional layer 30 to be achieved.

According to one embodiment of the manufacturing method, the light guide 20 is manufactured using an additive material application method. According to this alternative embodiment, the step of providing the light guide blank and the step of forming the light guide 20 by means of a laser process or a material-removing process are omitted. The additive material application process is, for example, a 3D printing process or a pipetting process using a nanopipetting robot. An advantage of using a 3D printing method is that the light guide 20 can be produced in geometries that can only be produced with great effort or not at all using other production methods.

According to an embodiment of the manufacturing method, this embodiment being compatible with all the described embodiments, and in 4 is shown, a reflection layer 60 is applied to the second end 22 of the light guide 20 before the step of applying the functional layer 30 . The reflective layer 60 is, for example, doctored or applied to the light guides 20 or, in the case of several light guides 20, to the individual light guides 20 by means of a stencil. The reflection layer 60 is produced, for example, by vapor-depositing silver or aluminum onto the light guide 20 .

According to an embodiment of the manufacturing method, which in 6 and 7 is shown, after the step of applying the functional layer 30, a gas-permeable and/or a water-permeable membrane layer 40 is applied. If the membrane layer 40 is a water-permeable layer, the membrane layer 40 preferably has a hydrogel. If the membrane layer 40 is gas permeable, the membrane layer 40 preferably comprises a polymer such as a silicone or a fluoropolymer.

According to an embodiment of the manufacturing method, which in 6 and 7 is shown, after the step of applying the membrane layer 40, an optical insulation layer 40' is applied. The optical isolation layer 40' absorbs light.

According to an embodiment of the manufacturing method, which in 7 and 8th is shown, after the step of applying the functional layer 30 or after the step of applying the membrane layer 40, a protective layer 50 is applied. The protective layer 50 is preferably a layer which enables the sensor element 10 to work in a measuring medium M with particularly hygienic regulations, for example food, to measure. The protective layer 50 is made, for example, from a superhydrophilic polymer or coating or a superhydrophobic/hydrophobic polymer/coating.

Reference List

1

sensor system

2

light source

3

detector

4

control unit

5

light fiber

6

filter

10

sensor element

20

light guide

21

first end

22

second end

23

lateral surface

30

functional layer

40

membrane layer

40`

optical isolation layer

50

protective layer

60, 60'

reflective layer

S

stimulation light

L

luminescent light

A

axis

M

measuring medium

N

analyte

Claims (11)

Sensor element (10) for detecting an analyte, comprising: - A light guide (20) which extends along an axis (A) and has a first end (21), a second end (22) and a lateral surface (21) extending between the first end (21) and the second end (22). 23), wherein the light guide (20) is suitable for introducing a stimulation light (S) into the light guide (20) at the first end (21), - A functional layer (30) which is arranged on the light guide (20) so that the lateral surface (23) is covered by the functional layer (30), the functional layer (30) being suitable for being stimulated by the stimulation light (S). to emit a luminescent light (L). Sensor element (10) according to claim 1 , wherein the functional layer (30) is covered by a gas-permeable and/or water-permeable membrane layer (40). Sensor element (10) according to claim 2 , wherein the gas-permeable and/or water-permeable membrane layer (40) is covered by a gas-permeable and/or water-permeable protective layer (50). Sensor element (10) according to one of the preceding claims, wherein a reflection layer (60) is arranged at the second end (22), and the reflection layer (60) is suitable for reflecting the stimulation light (S). Sensor element (10) according to one of the preceding claims, wherein the light guide (20) has a refractive index greater than the refractive index of the functional layer (30). Sensor element according to one of the preceding claims, characterized in that a reflection layer (60`) and/or an optical insulation layer (40`) is applied to the functional layer (30). Sensor element (10) according to any one of the preceding claims, wherein the light guide (20) has a cylindrical shape, a truncated cone shape, a cone shape, a pyramidal shape or a tetragonal shape. Sensor system (1) comprising, - at least one sensor element (10) according to one of Claims 1 until 7 - a light source (2) which is suitable for emitting a stimulation light (S) and is arranged in such a way that the stimulation light (S) can be introduced into the light guide (20) at the first end (21) of the light guide (20). , - a detector (3) which is suitable for detecting a luminescent light (L), - a control unit (4) which is connected to the light source (2) and the detector (3), and thereto is suitable for controlling an emission of the stimulation light (S) of the light source (2) and for evaluating a luminescence light (L) detected by the detector (3). Sensor system (1) according to claim 8 , wherein the light source (2) and the detector (3) are each connected via an optical fiber (5) to the first end (21) of the light guide (20). Method for producing a sensor element (10) comprising the following steps: - Provision of a light guide blank, - Forming at least one light guide (20) by means of a laser process or a material removal process, - Application of a functional layer (30) to the at least one light guide (20) by means of an immersion method, spray coating method, spin coating method or inkjet method. Method for producing a sensor element (10) comprising the following steps: - Forming at least one light guide (20) by means of an additive material application method, in particular a 3D printing method, - Application of a functional layer (30) to the at least one light guide (20) by means of an immersion method, spray coating method, spin coating method or inkjet method.

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