Flow cell for optical measurements, optical module and spectrometer

Abstract

A flow cell for optical measurements comprises a main body 1 with an inlet 2 and an outlet 3 and also comprises an aperture 4 arranged on a first outer side of the main body, wherein a clearance 5 containing a flow-cell measuring chamber connected to the inlet and the outlet is provided on the first outer side of the main body. The flow cell also comprises an arrangement which comprises an ATR crystal 7 and a sealing element 8 for sealing the flow-cell measuring chamber and is clamped in between the aperture and at least a first wall region of the clearance. The materials of the main body and the aperture differ in their coefficients of thermal expansion, and the aperture can be fixed on the main body at a first fixing point by a first fixing means in such a way that, at the first fixing point, the main body and the aperture are not movable relative to one another in an x direction, running parallel to the first outer side of the main body, in a y direction, running parallel to the first outer side of the main body, and in a z direction, running perpendicularly to the first outer side of the main body, and can be fixed on the main body at a second fixing point by a second fixing means 10 in such a way that, at the second fixing point, the main body and the aperture are movable relative to one another in the x direction and in the y direction, though in each case only to the extent that different expansions and / or contractions of the components of the flow cell that take place when there are changes in temperature can be compensated. In addition or as an alternative, the flow cell comprises a filter element 15, which is arranged in the clearance between the ATR crystal and an opening connected to the inlet and / or between the ATR crystal and an opening connected to the outlet.

Description

[0001] Flow cell for optical measurements, optical module and spectrometer

[0002] The present invention relates to a flow cell for optical measurements. The flow cell comprises a base body with at least one inlet and at least one outlet for substances to be measured and a

[0003] An aperture arranged on the outside of the base body, wherein a recess is provided on the first outside of the base body, said recess containing a flow cell measuring chamber connected to the at least one inlet and the at least one outlet. The flow cell comprises an arrangement comprising an ATR crystal and at least one first sealing element for sealing the flow cell measuring chamber, clamped between the aperture and at least one first wall region of the recess, wherein the at least one first sealing element is arranged on a side of the ATR crystal facing away from the aperture. The present invention further relates to an optical module comprising the flow cell according to the invention and to a spectrometer comprising the optical module.In recent decades, growing interest in the integration of continuous bioprocesses has led to the development and implementation of process analytical technologies (PATs) capable of monitoring key process parameters in real time. Adapting these technologies to continuous processing aims to achieve a better understanding of the process. This leads to shortened production cycles and ultimately increased yield and productivity.

[0004] Protein concentration is a fundamental parameter that must be monitored in downstream processes. Therefore, there is a growing need to transition protein concentration measurement from offline to inline analysis. For this purpose, spectroscopic techniques have proven to be powerful analytical tools, enabling continuous and simultaneous monitoring of critical quality attributes, particularly the concentrations of metabolites, nutrients, and excipients.

[0005] For optical or spectroscopic measurements for inline analysis, a flow cell can be used as a component of the optical module of a spectrometer. A portion of the reaction mixture can be drawn from the reactor during the process, then passed through the flow cell, and then returned to the reactor. The reaction mixture is optically or spectroscopically measured within a measuring chamber as it passes through the flow cell, for example, to determine concentrations of metabolites, nutrients, and excipients in the reaction mixture.

[0006] Problems with such measurements can arise primarily from contamination with microorganisms, such as bacteria, viruses, or fungal spores, or from deposits of microorganisms, biomolecules, or cell debris in the flow cell measurement chamber. For example, microorganisms that enter the flow cell measurement chamber from outside can be transported into the reactor with the measured reaction mixture, leading to contamination of the reactor and the reaction product produced therein. Furthermore, deposits of microorganisms, biomolecules, or cell debris in the flow cell measurement chamber can lead to a deterioration of the optical measurements.

[0007] Based on this, the object of the present invention was to provide a flow cell for optical measurements with which contamination of the flow cell measuring chamber and / or the substances measured therein can be better avoided.

[0008] This object is achieved with respect to a flow cell having the features of patent claim 1, with respect to an optical module having the features of patent claim 12, and with respect to a spectrometer having the features of patent claim 15. The respective dependent patent claims represent advantageous developments.

[0009] According to the invention, a flow cell for optical measurements (or for use in optical measurements) is thus specified, which comprises a base body with at least one inlet (for substances to be measured) and at least one outlet (for measured substances) and an aperture arranged on a first outer side of the base body, wherein a recess is provided on the first outer side of the base body, which contains a flow cell measuring chamber (fluidically) connected to the at least one inlet and the at least one outlet, wherein the base body can preferably consist of at least one material which has a first thermal expansion coefficient and the aperture can consist of at least one material which has a second thermal expansion coefficient different from the first thermal expansion coefficient.

[0010] The first thermal expansion coefficient and the second thermal expansion coefficient can be determined, for example, by dilatometry, e.g. according to ISO 11359-2:2021-11.

[0011] Preferably, the second thermal expansion coefficient differs by at least 10 • 10 -6 K -1 , preferably by at least 20 • 10 -6 K -1 , particularly preferably by at least 50 • 10 -6 K -1 , most preferably by at least 80 • 10 -6 K -1 , e.g. around 80 • 10 -6 K 1 up to 200 • 10 -6 K 1from the first thermal expansion coefficient. Furthermore, the flow cell comprises an arrangement comprising an ATR crystal and at least one first sealing element for sealing the flow cell measuring chamber, clamped between the aperture and at least one first wall region of the recess (facing the aperture), wherein the at least one first sealing element is arranged on a side of the ATR crystal facing away from the aperture.

[0012] An ATR crystal is an element that can be used as an ATR crystal or ATR element in ATR infrared spectroscopy (ATR = "attenuated total reflection").

[0013] It is provided that the base body consists of at least one material which has a first thermal expansion coefficient and the aperture consists of at least one material which has a second thermal expansion coefficient which differs from the first thermal expansion coefficient, wherein the aperture can be fixed to at least one first fixing point on the base body via at least one first fixing means such that the base body and the aperture are essentially not movable relative to one another at the at least one first fixing point in an x-direction running parallel to the first outer side of the base body, in a y-direction running parallel to the first outer side of the base body and in a z-direction running perpendicular to the first outer side of the base body,and wherein the aperture can be fixed to at least one second fixing point on the base body via at least one second fixing means such that the base body and the aperture are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and the y-direction only to the extent that different expansions and / or contractions of the flow cell components that occur during temperature changes can be compensated, and / or the flow cell comprises at least one filter element, which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet and / or between the ATR crystal and at least one opening connected to the at least one outlet.

[0014] The aperture can be fixed or secured to at least one first fixing point on the base body via at least one first fixing means such that the base body and the aperture are essentially not movable relative to one another at the at least one first fixing point in an x-direction running parallel to the first outer side of the base body, in a y-direction running parallel to the first outer side of the base body (and perpendicular to the x-direction), and in a z-direction running perpendicular to the first outer side of the base body. "Essentially not movable relative to one another" can be understood to mean that the base body and the aperture are movable relative to one another at the at least one first fixing point in the x-direction, the y-direction, and the z-direction by less than 10 μm each, preferably by at most 9 μm, particularly preferably by at most 5 μm, and most preferably by at most 1 μm.Particularly preferably, the base body and the aperture at the at least one first fixation point are not movable at all relative to each other in the x-direction, in the y-direction and in the z-direction.

[0015] In addition, the aperture can be fixed or secured to at least one second fixing point on the base body via at least one second fixing means in such a way that the base body and the aperture are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and in the y-direction only to the extent that, in the event of temperature changes (preferably of up to 80 K, particularly preferably of up to 120 K, e.g. from 10 K to 130 K), different expansions and / or contractions of the components of the flow cell (in particular of the base body and the aperture) can be compensated for (or can be compensated for in such a way that the temperature changes do not cause any bending or a bending of a maximum of 0.1 mm of the components of the flow cell - in particular of the base body and the aperture)."Substantially not movable relative to one another" can be understood to mean that the base body and the aperture at the at least one second fixation point are movable relative to one another in the z-direction by less than 10 pm, preferably by at most 9 pm, particularly preferably by at most 5 pm, most particularly preferably by at most 1 pm. Particularly preferably, the base body and the aperture are not movable relative to one another at all in the z-direction.

[0016] The value for the bending of the components (e.g. the base body and / or the aperture) can be determined as the distance between a point of the component in the unbent state in the middle (a direct connecting line) between the first fixation point and the second fixation point and the same point of the component in the bent state.

[0017] The base body and the aperture can be made of different materials, meaning the aperture can be made of a different material than the base body, so that the aperture material has a different thermal expansion coefficient than the base body material. By designing the flow cell with a base body and an aperture made of different materials, the different areas of the flow cell can be better adapted to specific requirements compared to flow cells where the base body and aperture are implemented in a single element made of a single material.

[0018] The base body can contain a flow structure, e.g., a channel structure, through which the substances to be measured or measured are guided through the flow cell (or from the inlet to the flow cell measuring chamber and from the flow cell measuring chamber to the outlet). The base body can preferably be a polymeric, e.g., thermoplastic, base body, which can be produced, for example, by means of 3D printing. In this way, a base body with a suitable - possibly complex - channel structure can be realized in a simple and inexpensive manner. The aperture can serve as a connecting element of the flow cell to a module main body of an optical module. The aperture can be made of a harder material (preferably an alloy, e.g.,stainless steel) than the base body, so that in this way a very strong connection of the flow cell to the module main body can be achieved and a sealing element used to seal the connection between the flow cell and the module main body can seal well.

[0019] The aperture is located on the first outer side of the base body, where the recess containing the flow cell measuring chamber is also located. Thus, the recess containing the flow cell measuring chamber borders the aperture. The aperture diaphragm can be located in this area of ​​the aperture, so that the aperture diaphragm borders the recess.

[0020] The arrangement comprising the ATR crystal and the at least one first sealing element for sealing the flow cell measuring chamber is clamped between the aperture and the at least one first wall region of the recess (facing the aperture), wherein the at least one first sealing element is arranged on a side of the ATR crystal facing away from the aperture. As a result, the flow cell chamber can now be designed such that it is delimited by the ATR crystal, the at least one first sealing element, and wall regions of the recess. By fixing the aperture to the base body, the arrangement comprising the ATR crystal and the at least one first sealing element for sealing the flow cell measuring chamber can be clamped between the aperture and the at least one first wall region of the recess (facing the aperture), thus sealing the flow cell chamber.

[0021] If the base body and the aperture (and possibly also the ATR crystal and / or the at least one first sealing element) are made of materials with different thermal expansion coefficients, a significant temperature change (e.g. during sterilization or autoclaving of the flow cell) can lead to different expansion of the components (i.e. the base body and the aperture and possibly the ATR crystal and / or the at least one first sealing element). If the aperture were fixed to the base body in such a way that at all fixing points the base body and the aperture are in all three spatial directions (i.e.Since the components (i.e. in the x-direction, in the y-direction and in the z-direction) are essentially not movable relative to one another, the different expansion of the components leads to stresses which can lead to a bending of the components, which can lead to a loosening of the clamped arrangement comprising the ATR crystal and the at least one first sealing element, which ultimately leads to leaks in the arrangement at which the flow cell measuring chamber is no longer sufficiently sealed, so that on the one hand the reaction mixture can escape to the outside through the leaks and on the other hand contaminants or microorganisms from the outside can enter the flow cell chamber through the leaks.

[0022] This can be prevented by a special fastening of the aperture to the base body. In this case, the aperture can be fixed to the at least one first fixing point on the base body via the at least one first fixing means in such a way that the base body and the aperture at the at least one first fixing point are orientable in all three spatial directions (iein the x-direction, in the y-direction and in the z-direction) are essentially not movable relative to one another, whereas the aperture can be fixed to the at least one second fixing point on the base body via the at least one second fixing means in such a way that the base body and the aperture are essentially not movable relative to one another in the z-direction at the at least one second fixing point, and are movable relative to one another in the x-direction and in the y-direction only to the extent that different expansions and / or contractions of the components of the flow cell that occur when temperature changes can be compensated for. The at least one second fixing means thus guarantees a certain mobility of the base body and the aperture relative to one another in the x- and y-direction, by means of which different expansions and / or contractions of the components can be compensated for.As a result, although there is still varying expansion of the components in the event of significant temperature changes (e.g. during sterilization or autoclaving of the flow cell), this does not lead to bending of the components (due to a certain degree of mobility in the x and y directions), and therefore the clamped arrangement comprising the ATR crystal and the at least one first sealing element does not become loose. This prevents the formation of leaks in the arrangement at which the flow cell measuring chamber is no longer sufficiently sealed. Consequently, the flow cell is highly leak-tight - even in the event of significant temperature changes (e.g. during sterilization or autoclaving of the flow cell), so that contaminants can no longer enter the flow cell chamber through leaks from the outside.As a result, contamination of the flow cell chamber and the substances measured therein by external contaminants or microorganisms can be better avoided.

[0023] The flow cell can comprise at least one filter element, which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet and / or between the ATR crystal and at least one opening connected to the at least one outlet. The object of the present invention can also be achieved in this way, as explained below.

[0024] The substances being measured, which are passed through the flow cell, may contain larger molecules (e.g., proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. This deposit or biofouling subsequently leads to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum, thus affecting the quality of the measurement. Furthermore, deposits on the ATR crystal can contaminate the substance being measured there in a subsequent measurement.

[0025] The at least one filter element, which can be arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet, can now keep larger molecules (e.g., proteins), cell debris, and microorganisms contained in the substances to be measured away from the ATR crystal, as these components are retained by the filter element, while the liquid containing the smaller molecules relevant for the optical measurement passes through the filter element. As a result, deposits or biofouling on the ATR crystal can be better prevented. Consequently, the filter element can better prevent contamination of the flow cell chamber and also of the substances to be measured (in the future) therein.

[0026] In addition, the filter element can also keep away from the ATR crystal any gas bubbles present in the substances to be measured, which, if they attach to the ATR crystal, would also lead to an undesired influence on the measurement or the measured spectrum.

[0027] Advantageously, the flow cell according to the invention can be used as a replaceable and / or disposable product. Preferably, the flow cell according to the invention is a replaceable and / or disposable product. A replaceable flow cell allows for sterilization and replacement, since the surface of ATR crystals quickly becomes dirty in bioprocesses.

[0028] Instead of fixing the aperture to the base body via the aforementioned at least one first fixing means and the aforementioned at least one second fixing means, the aperture can also be attached to the base body in another way. For example, the aperture can be attached (or glued) to the base body using at least one adhesive.

[0029] A preferred embodiment of the flow cell according to the invention is characterized in that the aperture can be fixed to the at least one second fixing point on the base body via the at least one second fixing means in such a way that the base body and the aperture at the at least one second fixing point are essentially not movable relative to one another in the z-direction and are movable relative to one another in the x-direction and in the y-direction by at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.1 mm, and / or by at most 1 mm, preferably at most 0.8 mm, particularly preferably at most 0.5 mm."Substantially not movable relative to one another" can be understood to mean that the base body and the aperture at the at least one second fixation point are movable relative to one another in the z-direction by less than 10 μm, preferably by at most 9 μm, particularly preferably by at most 5 μm, most particularly preferably by at most 1 μm. Particularly preferably, the base body and the aperture are not movable relative to one another at all in the z-direction.

[0030] A further preferred embodiment of the flow cell according to the invention is characterized in that the at least one first fixing means is selected from the group consisting of countersunk head screws, as well as combinations thereof, wherein the at least one first fixing means is preferably at least one countersunk head screw, and / or the at least one second fixing means is selected from the group consisting of lens head screws, rivets, cylinder head screws, as well as combinations thereof, wherein the at least one first fixing means is preferably at least one lens head screw

[0031] With these special fixation means, the desired immobility in all three spatial directions at the at least one first fixation point and in the z-direction at the at least one second fixation point as well as the desired limited mobility in the x- and y-direction at the at least one second fixation point can be achieved in a simple manner.

[0032] A further preferred embodiment of the flow cell according to the invention is characterized in that the at least one material from which the base body is made is at least one polymer, particularly preferably at least one thermoplastic polymer. Most preferably, the material from which the base body is made is at least one polymer selected from the group consisting of polyetheretherketones, polytetrafluoroethylene, polypropylene, polysulfones, polyethersulfones, polycarbonates, polyvinyl chlorides, polylactides, polyamides, thermoplastic polyurethanes, acrylonitrile-butadiene-styrene, UV-curing (autoclavable) synthetic resins, and mixtures thereof. In this case, the base body can be produced simply and inexpensively using 3D printing. This allows a flow or channel structure to be easily realized.For example, the at least one material comprising the base body may contain or consist of bisphenol A dimethacrylate, 2-hydroxyethyl methacrylate, and urethane dimethacrylate. For example, the product "BioMed Clear" from the manufacturer formlabs can be used as the material for the base body.

[0033] According to a further preferred embodiment of the flow cell according to the invention, the at least one material from which the aperture is made is selected from the group consisting of metals, e.g., iron; alloys, preferably iron-containing alloys, e.g., stainless steel; polymers, e.g., polyetheretherketones; and mixtures and combinations thereof, wherein the aperture preferably contains or consists of stainless steel. In this way, a very strong connection of the flow cell to a module main body of an optical module can be achieved, so that a sealing element used to seal the connection between the flow cell and the module main body can provide a good seal.

[0034] A further preferred embodiment of the flow cell according to the invention is characterized in that the ATR crystal contains or consists of at least one material which is at least partially transparent to light with a wavelength in the range from 2 pm to 20 pm, preferably from 4 pm to 12 pm, wherein the ATR crystal preferably contains or consists of at least one material which is selected from the group consisting of silicon, diamond, germanium, zinc selenide, zinc sulfide, and mixtures and combinations thereof, wherein the ATR crystal particularly preferably contains or consists of silicon, and / or comprises a plurality of microprisms, and / or has a structuring, preferably structuring with grooves or notches, particularly preferably a structuring with V-shaped grooves or V-shaped notches, on a side facing the aperture.

[0035] The transparency of the at least one material that the ATR crystal contains or consists of can be determined, for example, by means of DIN 4522-4:1993-04.

[0036] Preferably, the at least one material that the ATR crystal contains or consists of, at least in part, has a transmittance for light with a wavelength in the range of 2 pm to 20 pm, preferably 4 pm to 12 pm, of more than 10%. The transmittance can be determined, for example, according to DIN 4522-4:1993-04.

[0037] Microprisms enable high light throughput while maintaining low positioning accuracy. Structuring with grooves or notches makes it easy for the light to be coupled in, reducing positioning accuracy.

[0038] A further preferred embodiment of the flow cell according to the invention is characterized in that the at least one first sealing element

[0039] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0040] • is designed in the form of a circular ring, and / or

[0041] • is in sealing contact with the ATR crystal and / or the at least one first wall region of the recess and / or the flow cell comprises at least one second sealing element which is arranged around the recess, wherein the at least one second sealing element is preferably

[0042] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0043] • is designed in the form of a circular ring, and / or • is arranged at least partially in a further recess arranged around the recess on the first outer side of the base body, and / or

[0044] • is in sealing contact with the base body and / or the aperture.

[0045] Because the at least one first sealing element contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or is designed in the form of a circular ring, and / or is in sealing contact with the ATR crystal and / or the at least one first wall region of the recess, a good seal of the flow cell measuring chamber can be achieved in a simple manner by the at least one first sealing element. It should be noted that it is also possible in principle for the at least one first sealing element not to be in contact with the ATR crystal and / or the at least one first wall region of the recess, namely e.g.when a further element is arranged between the at least one first sealing element and the ATR crystal or between the at least one first sealing element and the at least one first wall region of the recess.

[0046] The at least one second sealing element can ensure that no gases from the environment can enter areas (e.g. a cavity) between the ATR crystal and the aperture.

[0047] A further preferred embodiment of the flow cell according to the invention is characterized in that the flow cell comprises at least one filter element which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet (and / or between the ATR crystal and at least one opening connected to the at least one outlet), wherein preferably the at least one filter element is selected from the group consisting of cellulose filter elements, e.g.Filter elements made of regenerated cellulose; paper filter elements; glass fiber filter elements; cellulose acetate filter elements; polyethersulfone filter elements; nylon filter elements; polyvinylidene fluoride filter elements; polytetrafluoroethylene filter elements; polypropylene filter elements; polycarbonate filter elements; and combinations thereof, wherein the at least one filter element is preferably selected from the group consisting of cellulose filter elements, paper filter elements, glass fiber filter elements, and combinations thereof, and / or has a thickness in the range from 0.001 mm to 5 mm, preferably from 0.01 mm to 1 mm, particularly preferably from 0.02 mm to 0.2 mm.

[0048] The substances to be measured that are passed through the flow cell may contain larger molecules (e.g. proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. The deposits or biofouling subsequently lead to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum and therefore influence the quality of the measurement. In addition, deposits on the ATR crystal can contaminate the substance to be measured in a subsequent measurement. The filter element now allows larger molecules contained in the substances to be measured (e.g.Proteins), cell debris, and microorganisms are kept away from the ATR crystal, as these components are retained by the filter element, while the liquid containing the smaller molecules relevant for the optical measurement passes through the filter element. Consequently, the filter element can better prevent contamination of the flow cell chamber and the substances to be measured therein (in the future). Furthermore, the filter element can also keep away from the ATR crystal any gas bubbles present in the substances to be measured, which, if they attach to the ATR crystal, would also lead to an undesired influence on the measurement or the measured spectrum.

[0049] Various materials can be used for the at least one filter element, preferably selected from the group consisting of cellulose, e.g. regenerated cellulose; paper; glass fiber; cellulose acetate; polyethersulfone; nylon; polyvinylidene fluoride; polytetrafluoroethylene; polypropylene; polycarbonate; and combinations thereof. Cellulose acetate has good chemical resistance and low protein binding. Polyethersulfone (PES) enables high flow rates and has low protein binding. Nylon has high mechanical strength and good chemical resistance. Polyvinylidene fluoride (PVDF) has high chemical resistance but low protein binding. Polytetrafluoroethylene (PTFE) is extremely chemically resistant and good for aggressive solvents. Polypropylene is chemically resistant and has lower protein binding compared to other materials.Regenerated cellulose (RC): has good chemical resistance and low protein binding. Polycarbonates can be used for track-etched membranes with uniform pore sizes.

[0050] It is also possible that the flow cell does not have a filter element which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet and / or between the ATR crystal and at least one opening connected to the at least one outlet.

[0051] A further preferred embodiment of the flow cell according to the invention is characterized in that the flow cell additionally comprises at least one filter holder for holding the at least one filter element, which is arranged between the ATR crystal and the at least one filter element, wherein the at least one filter holder preferably has a grid structure and a frame extending around the grid structure.It is particularly preferred here that the frame is in contact with the ATR crystal and the grating structure is not in contact with the ATR crystal, wherein the grating structure is preferably arranged at a distance of 0.001 mm to 5 mm, preferably from 0.005 mm to 2 mm, particularly preferably from 0.008 mm to 1 mm, very particularly preferably from 0.01 mm to 0.1 mm, from the ATR crystal, and / or the at least one filter element is clamped between the frame and at least one second wall region of the recess facing the aperture, and / or a central wall region of the recess facing the aperture has at least one holding element, preferably at least two holding elements, wherein the at least one filter element is clamped between the grating structure and the at least one holding element.

[0052] The filter holders allow the filter element to be placed at a convenient distance from the ATR crystal, preventing the filter from coming into contact with the ATR crystal and thus interfering with the optical measurement. The grid structure can easily prevent a central area of ​​the filter, which is saturated with the substance to be measured, from sagging and coming into contact with the ATR crystal. The at least one retaining element in the central wall area of ​​the recess also allows the filter to be better secured, thus better preventing the filter from slipping.

[0053] A further preferred embodiment of the flow cell according to the invention is characterized in that the at least one filter element is arranged in direct contact with at least one photoresist coating applied to the ATR crystal, wherein the at least one photoresist coating preferably has a thickness in the range from 0.1 pm to 100 pm, preferably from 1 pm to 50 pm, particularly preferably from 5 pm to 20 pm, and / or the at least one photoresist coating is applied to the ATR crystal in the form of a grid or in strip form, wherein the arrangement of the photoresist coating on the ATR crystal is preferably adapted to a structuring of the ATR crystal which the ATR crystal has on a side facing the aperture, and / or the at least one filter element is fastened to the at least one first sealing element, preferably is integrally connected to the at least one first sealing element.A conventional photoresist commonly used in the state of the art can be used for the photoresist coating. This photoresist allows for very precise and thin coatings. Thus, the photoresist coating allows the filter element to be placed at an advantageous, very small distance from the ATR crystal. This prevents the filter from coming into contact with the ATR crystal and thereby interfering with the optical measurement. Furthermore, only very small amounts of liquid remain between the ATR crystal and the filter element, resulting in a very short diffusion time and thus a significant increase in measurement speed (or a reduction in time offset). Because the at least one photoresist coating is applied to the ATR crystal in the form of a grid or strip, interference with the optical measurement caused by the photoresist coating can be prevented or at least minimized.Particularly preferably, the arrangement of the photoresist coating on the ATR crystal can be adapted to a structuring of the ATR crystal which the ATR crystal has on a side facing the aperture, so that the photoresist coating is applied only at those locations which are not reached by the optical rays (e.g. infrared rays) during an optical measurement.

[0054] If, for example, the ATR crystal has a structure with grooves or notches on a side facing the aperture, the photoresist coating can only be applied to those strip-shaped areas that run along these grooves or notches (on the opposite side of the ATR crystal).

[0055] For example, the light path through the geometry (of the ATR crystal or the pattern on the ATR crystal) can be selected such that unilluminated areas are created on top of the ATR crystal. A spacer (e.g., the photoresist coating or the filter holder) can be applied to these areas. This spacer can be manufactured using various processes, such as lithography, 3D printing, or CNC / CAM (CNC = "Computerized Numerical Control"; CAM = "Computer-Aided Manufacturing"). The filter (or the actual filter membrane) can be applied to this spacer.

[0056] A further preferred embodiment of the flow cell according to the invention is characterized in that the at least one filter element is arranged in direct contact with at least one spacer arranged, preferably applied, on the ATR crystal, wherein the at least one spacer preferably has a thickness in the range from 0.1 µm to 100 µm, preferably from 1 µm to 50 µm, particularly preferably from 5 µm to 20 µm, and / or the at least one spacer is applied to the ATR crystal in the form of a grid or in strip form, wherein the arrangement of the spacer on the ATR crystal is preferably adapted to a structuring of the ATR crystal which the ATR crystal has on a side facing the aperture (e.g. adapted such that it is arranged only in those regions which, due to the structuring of the ATR crystal (orthe geometry of the structuring) are not reached (or illuminated) by optical rays during an optical measurement), and / or the at least one spacer is fastened to the at least one first sealing element, preferably is materially connected to the at least one first sealing element, and / or the at least one spacer can be produced or is produced by means of a method selected from the group consisting of lithography, 3D printing, CNC ("Computerized Numerical Control"), and combinations thereof, and / or the at least one spacer is at least one photoresist coating, and / or is arranged only in those regions which, due to a structuring of the ATR crystal (or the geometry of the structuring) which the ATR crystal has on a side facing the aperture, are not reached (or illuminated) by optical rays during an optical measurement.

[0057] There are various options for implementing the spacer. For example, grooves can be etched into the wafer in the area where the beams hit, creating raised stripes that serve as spacers for the filter. Or, stripes can be applied to the optically inactive areas. These stripes can be created using photoresist, a precision foil, or micro 3D printing. It is also conceivable that these stripes are very thin, periodically arranged wires. The second option (i.e., applying stripes to the optically inactive areas) is more advantageous, since any etching of the surface roughens it, which can also lead to optical problems.

[0058] Furthermore, it is also possible in principle for the at least one filter element to be arranged in direct contact with the at least one ATR crystal, i.e., without any gap between the filter element and the ATR crystal. In this case, neither a filter holder nor a photoresist coating is required.

[0059] A further preferred embodiment of the flow cell according to the invention is characterized in that the aperture is arranged between the at least one first fixing point and the at least one second fixing point, wherein the at least one first fixing point and the at least one second fixing point preferably have the same distance from the recess, and / or has a structuring, preferably a serrated structuring, on a central wall region of the recess facing the aperture, and / or has at least one opening connected to the at least one inlet on a central wall region of the recess facing the aperture, and / or has at least one opening connected to the at least one outlet on a central wall region of the recess facing the aperture.

[0060] The (serrated) structuring helps prevent biofouling on the filter element.

[0061] By arranging the recess between the at least one first fixation point and the at least one second fixation point, or by arranging the fixation points (with the fixation elements) such that the recess (and thus also the flow cell measuring chamber) lies between the two fixation points, in particular exactly in the middle between the two fixation points, particularly good fixation with a particularly high degree of tightness of the flow cell measuring chamber can be achieved. The distance between the at least one first fixation point and the at least one second fixation point is preferably 5 mm to 100 mm, preferably 15 mm to 50 mm, particularly preferably 20 mm to 40 mm.Preferably, the distance between the at least one first fixing point and the recess and / or the distance between the at least one second fixing point and the recess is 2 mm to 50 mm, preferably 7 mm to 25 mm, particularly preferably 10 mm to 20 mm.

[0062] A further preferred embodiment of the flow cell according to the invention is characterized in that the flow cell comprises at least one third fixing means, preferably a single third fixing means, for fastening the flow cell to a module main body of an optical module, wherein the at least one third fixing means has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture has a protruding area,which protrudes beyond a second outer side of the base body (adjacent to the first outer side of the base body), wherein the recess is preferably arranged between the second outer side of the base body and the at least one third fixing means, and / or the flow cell additionally comprises at least one third sealing element arranged around the at least one third fixing means and sealingly connected to the at least one third fixing means. The third fixing means allows the flow cell to be firmly connected to the main module body of an optical module in a simple manner.

[0063] It is preferred that the at least one third sealing element contains or consists of at least one polymer which is selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or is formed in the form of a circular ring

[0064] The present invention further relates to an optical module comprising a module main body and a flow cell according to the invention which is attached to the module main body.

[0065] A preferred embodiment of the optical module according to the invention is characterized in that the flow cell is fastened to the module main body via at least one third fixing means, preferably a single third fixing means, and a stop element arranged on an outer side of the module main body facing the flow cell, wherein the stop element has a stop surface against which the flow cell is pressed by the at least one third fixing means, and wherein preferably an angle between the stop surface and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 65°, particularly preferably from 40° to 50°, and / or the at least one third fixing means has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 70°,particularly preferably from 40° to 65°, and / or the at least one third fixing means is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture has a protruding region which protrudes beyond a second outer side of the base body (adjacent to the first outer side of the base body), wherein the protruding region is pressed against the stop surface, and wherein the recess is preferably arranged between the second outer side of the base body and the at least one third fixing means, and / or the flow cell additionally has at least one third sealing element,which is arranged around the at least one third fixing means and is sealingly connected to the at least one third fixing means.,

[0066] The third fixing means and the stop element enable the flow cell to be firmly connected to the main module body in a simple manner. The third fixing means can be attached at a specific angle to the first outer side of the base body so that the flow cell is pressed at a specific angle against the main module body and against the stop surface of the stop element, i.e. a first force component is directed towards the main module body and a second force component is directed towards the stop surface. The stop surface can then be arranged at a corresponding angle to the first outer side of the base body in order to effectively absorb the force component exerted by the fixing means on the stop surface and to redirect it onto the main module body. In this way, a very strong fixation can be achieved.

[0067] A preferred embodiment of the optical module according to the invention is characterized in that the module main body comprises a (single) lens for coupling in a light beam incident on the ATR crystal and for coupling out a light beam reflected by the ATR crystal, wherein the lens preferably contains or consists of zinc selenide, and / or comprises an optical window arranged between the ATR crystal and the lens, wherein the optical window preferably contains or consists of zinc sulfide, and / or comprises at least one fourth sealing element arranged on an outer side of the module main body facing the flow cell, which sealing element is in sealing contact with a side of the flow cell facing the module main body, wherein the at least one fourth sealing element is designed in the form of a circular ring,and / or a polarizer for polarizing a light beam reflected by the ATR crystal and subsequently coupled out.

[0068] The use of a single lens for coupling and decoupling the light has the advantage that it requires virtually no adjustment, as this design is self-correcting to a certain extent (cat's eye). This is advantageous for compensating for inaccuracies in the ATR crystal and the flow cell. The at least one fourth sealing element arranged on an outer side of the module main body facing the flow cell ensures that no gases or liquids penetrate the light path. This improves long-term stability, as water vapor in particular is IR-active. It is preferred that the at least one fourth sealing element contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof.

[0069] Furthermore, the present invention also relates to a spectrometer comprising at least one light source, at least one light detector, and an optical module according to the invention. The spectrometer is preferably an FTIR spectrometer and / or a QCL-based infrared spectrometer.

[0070] The present invention also relates to a flow cell for optical measurements (or for use in optical measurements), comprising a base body with at least one inlet (for substances to be measured) and at least one outlet (for measured substances) as well as a flow cell arranged on a first outer side of the base body (orattached) aperture, wherein a recess is provided on the first outer side of the base body, which recess contains a flow cell measuring chamber (fluidically) connected to the at least one inlet and the at least one outlet, wherein the flow cell further comprises an arrangement comprising an ATR crystal and at least one first sealing element for sealing the flow cell measuring chamber, clamped between the aperture and at least one first wall region of the recess (facing the aperture), wherein the at least one first sealing element is arranged on a side of the ATR crystal facing away from the aperture, and wherein the flow cell comprises at least one filter element which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet and / or between the ATR crystal and at least one opening connected to the at least one outlet.

[0071] The object of the present invention can also be achieved by this flow cell, as will be explained below.

[0072] The substances being measured, which are passed through the flow cell, may contain larger molecules (e.g., proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. This deposit or biofouling subsequently leads to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum, thus affecting the quality of the measurement. Furthermore, deposits on the ATR crystal can contaminate the substance being measured there in a subsequent measurement.

[0073] The at least one filter element, which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet, can now keep larger molecules (e.g., proteins), cell debris, and microorganisms contained in the substances to be measured away from the ATR crystal, as these components are retained by the filter element, while the liquid containing the smaller molecules relevant for the optical measurement passes through the filter element. As a result, deposits or biofouling on the ATR crystal can be better prevented. Consequently, the filter element can better prevent contamination of the flow cell chamber and also of the substances to be measured (in the future) therein.

[0074] In addition, the filter element can also keep away from the ATR crystal any gas bubbles present in the substances to be measured, which, if they attach to the ATR crystal, would also lead to an undesired influence on the measurement or the measured spectrum.

[0075] It is preferred that the base body consists of at least one material having a first thermal expansion coefficient, and the aperture consists of at least one material having a second thermal expansion coefficient different from the first thermal expansion coefficient.

[0076] The present invention also relates to the following aspects A1 to A15:

[0077] Aspect Al:

[0078] A flow cell (100) for optical measurements, comprising a base body (1) with at least one inlet (2) and at least one outlet (3) and an aperture (4) arranged on a first outer side of the base body (1), wherein a recess (5) is provided on the first outer side of the base body (1) which contains a flow cell measuring chamber connected to the at least one inlet (2) and the at least one outlet (3), wherein the base body (1) consists of at least one material which has a first thermal expansion coefficient and the aperture (4) consists of at least one material which has a second thermal expansion coefficient different from the first thermal expansion coefficient,wherein the flow cell (100) further comprises an arrangement comprising an ATR crystal (7) and at least one first sealing element (8) for sealing the flow cell measuring chamber, clamped between the aperture (4) and at least one first wall region of the recess (5), wherein the at least one first sealing element (8) is arranged on a side of the ATR crystal (7) facing away from the aperture (4), TI wherein the aperture (4) can be fixed to at least one first fixing point on the base body (1) via at least one first fixing means (9) such that the base body (1) and the aperture (4) are essentially not movable relative to one another at the at least one first fixing point in an x-direction running parallel to the first outer side of the base body (1), in a y-direction running parallel to the first outer side of the base body (1), and in a z-direction running perpendicular to the first outer side of the base body (1),and wherein the aperture can be fixed to at least one second fixing point on the base body (1) via at least one second fixing means (10) such that the base body (1) and the aperture (4) are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and in the y-direction only to the extent that different expansions and / or contractions of the components of the flow cell (100) occurring during temperature changes can be compensated.

[0079] Aspect A2:

[0080] Flow cell (100) according to the preceding aspect, characterized in that the aperture (4) can be fixed to the at least one second fixing point on the base body (1) via the at least one second fixing means (10) in such a way that the base body (1) and the aperture (4) are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and in the y-direction by at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.1 mm, and / or by at most 1 mm, preferably at most 0.8 mm, particularly preferably at most 0.5 mm.

[0081] Aspect A3:

[0082] Flow cell (100) according to one of the preceding aspects, characterized in that the at least one first fixing means (9) is selected from the group consisting of countersunk head screws, as well as combinations thereof, wherein the at least one first fixing means (9) is preferably at least one countersunk head screw, and / or the at least one second fixing means (10) is selected from the group consisting of lens head screws, rivets, cylinder head screws, as well as combinations thereof, wherein the at least one first fixing means (10) is preferably at least one lens head screw.

[0083] Aspect A4:

[0084] Flow cell (100) according to one of the preceding aspects, characterized in that the at least one material from which the base body (1) is made is at least one polymer, which is preferably selected from the group consisting of polyetheretherketones, polytetrafluoroethylene, polypropylene, polysulfones, polyethersulfones, polycarbonates, polyvinyl chlorides, polylactides, polyamides, thermoplastic polyurethanes, acrylonitrile-butadiene-styrene, UV-curing synthetic resins, and mixtures thereof, and / or the at least one material from which the aperture (4) is made is selected from the group consisting of metals, e.g. iron; alloys, preferably iron-containing alloys, e.g. stainless steel; polymers, e.g. polyetheretherketones; and mixtures and combinations thereof, wherein the aperture (4) preferably contains or consists of stainless steel.

[0085] Aspect A5:

[0086] Flow cell (100) according to one of the preceding aspects, characterized in that the ATR crystal (7) contains or consists of at least one material which is at least partially transparent to light with a wavelength in the range from 2 pm to 20 pm, preferably from 4 pm to 12 pm, wherein the ATR crystal (7) preferably contains or consists of at least one material which is selected from the group consisting of silicon, diamond, germanium, zinc selenide, zinc sulfide, and mixtures and combinations thereof, wherein the ATR crystal particularly preferably contains or consists of silicon, and / or comprises a plurality of microprisms, and / or has a structuring (7a) on a side facing the aperture, preferably a structuring (7a) with grooves or grooves.

[0087] Aspect A6:

[0088] Flow cell (100) according to one of the preceding aspects, characterized in that the at least one first sealing element (8)

[0089] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0090] • is designed in the form of a circular ring, and / or

[0091] • is in sealing contact with the ATR crystal (7) and / or the at least one first wall region of the recess (5) and / or the flow cell (100) comprises at least one second sealing element (11) which is arranged around the recess (5), wherein the at least one second sealing element (11) is preferably

[0092] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0093] • is designed in the form of a circular ring, and / or

[0094] • is arranged at least partially in a further recess arranged around the recess (5) on the first outer side of the base body (1), and / or

[0095] • is in sealing contact with the base body (1) and / or the aperture (4). Flow cell (100) according to one of the preceding aspects, characterized in that the flow cell (100) comprises at least one filter element (15) which is arranged in the recess (5) between the ATR crystal (7) and at least one opening connected to the at least one inlet (2) and / or between the ATR crystal (7) and at least one opening connected to the at least one outlet (3), wherein preferably the at least one filter element is selected (from the group consisting of cellulose filter elements, e.g.made of regenerated cellulose; paper filter elements; glass fiber filter elements; cellulose acetate filter elements; polyethersulfone filter elements; nylon filter elements; polyvinylidene fluoride filter elements; polytetrafluoroethylene filter elements; polypropylene filter elements; polycarbonate filter elements; and combinations thereof, wherein the at least one filter element is preferably selected) from the group consisting of cellulose filter elements, paper filter elements, glass fiber filter elements, and combinations thereof, and / or has a thickness in the range from 0.001 mm to 5 mm, preferably from 0.01 mm to 1 mm, particularly preferably from 0.02 mm to 0.2 mm.

[0096] Aspect A8:

[0097] Flow cell (100) according to aspect A7, characterized in that the flow cell (100) additionally comprises at least one filter holder (16) for holding the at least one filter element (15), which is arranged between the ATR crystal (7) and the at least one filter element (15), wherein the at least one filter holder (16) preferably has a grid structure and a frame extending around the grid structure, wherein the frame is in contact with the ATR crystal (7) and the grid structure is not in contact with the ATR crystal (7), wherein the grid structure is preferably arranged at a distance of 0.001 mm to 5 mm, preferably from 0.005 mm to 2 mm, particularly preferably from 0.008 mm to 1 mm, very particularly preferably from 0.01 mm to 0.1 mm, from the ATR crystal (7), and / or the at least one filter element (15) is arranged between the frame and at least one second wall area of ​​the recess (5) is clamped,and / or a central wall region of the recess (5) facing the aperture (4) has at least one holding element, preferably at least two holding elements, wherein the at least one filter element (15) is clamped between the grid structure and the at least one holding element.

[0098] Aspect A9:

[0099] Flow cell (100) according to aspect A7, characterized in that the at least one filter element (15) is arranged in direct contact with at least one photoresist coating (16) applied to the ATR crystal (7), wherein preferably the at least one photoresist coating (16) has a thickness in the range from 0.1 pm to 100 pm, preferably from 1 pm to 50 pm, particularly preferably from 5 pm to 20 pm, and / or the at least one photoresist coating (16) is applied in the form of a grid or in strip form to the ATR crystal (7), wherein the arrangement of the photoresist coating (16) on the ATR crystal (7) is preferably adapted to a structuring of the ATR crystal (7) which the ATR crystal (7) has on a side facing the aperture (4), and / or the at least one filter element (15) is fastened to the at least one first sealing element (8), preferably with which is integrally connected to at least one first sealing element (8).

[0100] Aspect A10:

[0101] Flow cell (100) according to one of the preceding aspects, characterized in that the recess (5) is arranged between the at least one first fixing point and the at least one second fixing point, wherein the at least one first fixing point and the at least one second fixing point preferably have the same distance from the recess (5), and / or has a structuring, preferably a serrated structuring, on a central wall region of the recess (5) facing the aperture (4), and / or has at least one inlet connected to the at least one inlet

[0102] (2) connected to the aperture (4), and / or at a central wall area of ​​the recess (5) facing the aperture (4) at least one outlet

[0103] (3) connected opening.

[0104] Aspect All:

[0105] Flow cell (100) according to one of the preceding aspects, characterized in that the flow cell (100) comprises at least one third fixing means (12), preferably a single third fixing means (12), for fastening the flow cell (100) to a module main body of an optical module, wherein the at least one third fixing means (12) has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body (1) lies in a range from 20° to 85°, preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means (12) is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means (12) is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw,and / or the aperture (4) has a protruding region (13) which projects beyond a second outer side of the base body (1), wherein the recess (5) is preferably arranged between the second outer side of the base body (1) and the at least one third fixing means (12), and / or the flow cell (100) additionally has at least one third sealing element (14) which is arranged around the at least one third fixing means (12) and is sealingly connected to the at least one third fixing means (12).

[0106] Aspect A12:

[0107] Optical module (1000) comprising a module main body (200) and a flow cell (100) according to one of the preceding aspects, which is attached to the module main body.

[0108] Aspect A13:

[0109] Optical module (1000) according to aspect A12, characterized in that the flow cell (100) is fastened to the module main body (200) via at least one third fixing means (12), preferably a single third fixing means (12), and a stop element (23) arranged on an outer side of the module main body (200) facing the flow cell (100), wherein the stop element (23) has a stop surface against which the flow cell (100) is pressed by the at least one third fixing means (12), and wherein preferably an angle between the stop surface and the first outer side of the base body (1) lies in a range from 20° to 85°, preferably from 30° to 65°, particularly preferably from 40° to 50°, and / or the at least one third fixing means (12) has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body (1) in a range of 20° to 85°,preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means (12) is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means (12) is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture (4) has a protruding region (13) that protrudes beyond a second outer side of the base body (1), wherein the protruding region (13) is pressed against the stop surface, and wherein the recess (5) is preferably arranged between the second outer side of the base body (1) and the at least one third fixing means (12), and / or the flow cell (100) additionally has at least one third sealing element (14) that is arranged around the at least one third fixing means (12).

[0110] Aspect A14:

[0111] Optical module (1000) according to aspect A12 or A13, characterized in that the module main body (200) comprises a lens (17) for coupling in a light beam incident on the ATR crystal (7) and for coupling out a light beam reflected by the ATR crystal (7), wherein the lens (17) preferably contains or consists of zinc selenide, and / or comprises an optical window (18) which is arranged between the ATR crystal (7) and the lens (17), wherein the optical window (18) preferably contains or consists of zinc sulfide, and / or comprises at least one fourth sealing element (19) arranged on an outer side of the module main body (200) facing the flow cell (100), which is in sealing contact with a side of the flow cell (100) facing the module main body (200), wherein the at least one fourth sealing element (19) is preferably in the form of a circular Rings are formed,and / or a polarizer (20) for polarizing a light beam reflected by the ATR crystal (7) and subsequently coupled out.,

[0112] Aspect A15:

[0113] Spectrometer comprising at least one light source, at least one light detector and an optical module (1000) according to one of aspects A12 to A14, wherein the spectrometer is preferably an FTIR spectrometer or a QCL-based infrared spectrometer.

[0114] The present invention also relates to the following aspects B1 to B15:

[0115] Aspect Bl:

[0116] Flow cell for optical measurements, comprising a base body with at least one inlet and at least one outlet and a flow cell arranged on a first outer side of the base body (orattached) aperture, wherein a recess is provided on the first outer side of the base body, which recess contains a flow cell measuring chamber connected to the at least one inlet and the at least one outlet, wherein the flow cell further comprises an arrangement comprising an ATR crystal and at least one (first) sealing element for sealing the flow cell measuring chamber, clamped between the aperture and at least one first wall region of the recess, wherein the at least one (first) sealing element is arranged on a side of the ATR crystal facing away from the aperture, and wherein the flow cell comprises at least one filter element which is arranged in the recess between the ATR crystal and at least one opening connected to the at least one inlet and / or between the ATR crystal and at least one opening connected to the at least one outlet.

[0117] Aspect B2:

[0118] Flow cell according to aspect B1, characterized in that the base body consists of at least one material having a first thermal expansion coefficient and / or the aperture consists of at least one material having a second thermal expansion coefficient different from the first thermal expansion coefficient, wherein preferably the aperture can be fixed to at least one first fixing point on the base body via at least one first fixing means such that the base body and the aperture are essentially not movable relative to one another at the at least one first fixing point in an x-direction running parallel to the first outer side of the base body, in a y-direction running parallel to the first outer side of the base body, and in a z-direction running perpendicular to the first outer side of the base body,and the aperture can be fixed to at least one second fixing point on the base body via at least one second fixing means in such a way that the base body and the aperture are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and the y-direction only to the extent that different expansions and / or contractions of the components of the flow cell (in particular of the base body and the aperture) that occur during temperature changes can be compensated (or can be compensated in such a way that the temperature changes do not cause any bending of the components of the flow cell - in particular of the base body and the aperture), wherein particularly preferably the aperture can be fixed to the at least one second fixing point on the base body via the at least one second fixing means,that the base body and the aperture at the at least one second fixation point are essentially not movable relative to each other in the z-direction and in the y-direction by at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.1 mm, and / or by at most 1 mm, preferably at most 0.8 mm, particularly preferably at most 0.5 mm, relative to each other.

[0119] Aspect B3:

[0120] Flow cell according to aspect B2, characterized in that the at least one first fixing means is selected from the group consisting of countersunk head screws, as well as combinations thereof, wherein the at least one first fixing means is preferably at least one countersunk head screw, and / or the at least one second fixing means is selected from the group consisting of lens head screws, rivets, cylinder head screws, as well as combinations thereof, wherein the at least one first fixing means is preferably at least one lens head screw

[0121] Aspect B4:

[0122] Flow cell according to one of aspects B1 to B3, characterized in that the base body contains or consists of at least one polymer, which is preferably selected from the group consisting of polyetheretherketones, polytetrafluoroethylene, polypropylene, polysulfones, polyethersulfones, polycarbonates, polyvinyl chlorides, polylactides, polyamides, thermoplastic polyurethanes, acrylonitrile-butadiene-styrene, UV-curing synthetic resins, and mixtures thereof, and / or the aperture contains or consists of at least one material, which is selected from the group consisting of metals, e.g. iron; alloys, preferably iron-containing alloys, e.g. stainless steel; polymers, e.g. polyetheretherketones; and mixtures and combinations thereof, wherein the aperture preferably contains or consists of stainless steel.

[0123] Aspect B5:

[0124] Flow cell according to one of aspects B1 to B4, characterized in that the ATR crystal contains or consists of at least one material which is transparent to light with a wavelength in the range from 2 pm to 20 pm, preferably from 4 pm to 12 pm, wherein the ATR crystal preferably contains or consists of at least one material which is selected from the group consisting of silicon, diamond, germanium, zinc selenide, zinc sulfide, and mixtures and combinations thereof, wherein the ATR crystal particularly preferably contains or consists of silicon, and / or comprises a plurality of microprisms, and / or has a structuring, preferably structuring with grooves (or notches), on a side facing the aperture.

[0125] Aspect B6:

[0126] Flow cell according to one of the aspects Bl to B5, characterized in that the at least one first sealing element

[0127] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0128] • is designed in the form of a circular ring, and / or

[0129] • is in sealing contact with the ATR crystal and / or the at least one first wall region of the recess and / or the flow cell comprises at least one second sealing element which is arranged around the recess, wherein the at least one second sealing element is preferably

[0130] • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or

[0131] • is designed in the form of a circular ring, and / or

[0132] • is arranged at least partially in a further recess arranged around the recess on the first outer side of the base body, and / or

[0133] • is in sealing contact with the base body and / or the aperture.

[0134] Flow cell according to one of aspects B1 to B6, characterized in that the at least one filter element is selected from the group consisting of cellulose filter elements, paper filter elements, glass fiber filter elements, and combinations thereof, and / or has a thickness in the range from 0.001 mm to 5 mm, preferably from 0.01 mm to 1 mm, particularly preferably from 0.02 mm to 0.2 mm.

[0135] Aspect B8:

[0136] Flow cell according to one of the aspects B1 to B7, characterized in that the flow cell additionally comprises at least one filter holder for holding the at least one filter element, which is arranged between the ATR crystal and the at least one filter element, wherein the at least one filter holder preferably has a grid structure and a frame running around the grid structure, wherein the frame is in contact with the ATR crystal and the grid structure is not in contact with the ATR crystal, wherein the grid structure is preferably at a distance of 0.001 mm to 5 mm, preferably from 0.005 mm to 2 mm, particularly preferably from 0.008 mm to

[0137] 1 mm, very particularly preferably from 0.01 mm to 0.1 mm, to the ATR crystal, and / or the at least one filter element is clamped between the frame and at least one second wall region of the recess facing the aperture, and / or a central wall region of the recess facing the aperture has at least one holding element, preferably at least two holding elements, wherein the at least one filter element is clamped between the grid structure and the at least one holding element.

[0138] Aspect B9:

[0139] Flow cell according to one of aspects B1 to B7, characterized in that the at least one filter element is arranged in direct contact with at least one photoresist coating applied to the ATR crystal, wherein the at least one photoresist coating preferably has a thickness in the range from 0.1 pm to 100 pm, preferably from 1 pm to 50 pm, particularly preferably from 5 pm to 20 pm, and / or the at least one photoresist coating is applied to the ATR crystal in the form of a grid or in strip form, wherein the arrangement of the photoresist coating on the ATR crystal is preferably adapted to a structuring of the ATR crystal which the ATR crystal has on a side facing the aperture, and / or the at least one filter element is fastened to the at least one first sealing element, preferably is integrally connected to the at least one first sealing element.

[0140] Aspect B10:

[0141] Flow cell according to one of aspects B1 to B9, characterized in that the recess is arranged between the at least one first fixing point and the at least one second fixing point, wherein the at least one first fixing point and the at least one second fixing point preferably have the same distance from the recess, have a structuring, preferably a serrated structuring, on a central wall region of the recess facing the aperture, and / or have at least one opening connected to the at least one inlet on a central wall region of the recess facing the aperture, and / or have at least one opening connected to the at least one outlet on a central wall region of the recess facing the aperture.

[0142] Aspect Bll:

[0143] Flow cell according to one of aspects B1 to B10, characterized in that the flow cell comprises at least one third fixing means, preferably a single third fixing means, for fastening the flow cell to a module main body of an optical module, wherein the at least one third fixing means has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture has a protruding region,which protrudes beyond a second outer side of the base body (adjacent to the first outer side of the base body), wherein the recess is preferably arranged between the second outer side of the base body and the at least one third fixing means (and / or the flow cell additionally comprises at least one third sealing element which is arranged around the at least one third fixing means and is sealingly connected to the at least one third fixing means).

[0144] Aspect B12:

[0145] Optical module comprising a module main body and a flow cell according to one of the aspects Bl to Bll, which is attached to the module main body.

[0146] Aspect B13:

[0147] Optical module according to aspect B12, characterized in that the flow cell is fastened to the module main body via at least one third fixing means, preferably a single third fixing means, and a stop element arranged on an outer side of the module main body facing the flow cell, wherein the stop element has a stop surface against which the flow cell is pressed by the at least one third fixing means, and wherein preferably an angle between the stop surface and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 65°, particularly preferably from 40° to 50°, and / or the at least one third fixing means has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body lies in a range from 20° to 85°, preferably from 30° to 70°, particularly preferably from 40° to 65°,and / or the at least one third fixing means is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture has a protruding region that protrudes beyond a second outer side of the base body (adjacent to the first outer side of the base body), wherein the protruding region is pressed against the stop surface, and wherein the recess is preferably arranged between the second outer side of the base body and the at least one third fixing means (and / or the flow cell additionally has at least one third sealing element arranged around the at least one third fixing means).

[0148] Aspect B14:

[0149] Optical module according to aspect B12 or B13, characterized in that the module main body comprises a lens for coupling in a light beam incident on the ATR crystal and for coupling out a light beam reflected by the ATR crystal, wherein the lens preferably contains or consists of zinc selenide, and / or comprises an optical window arranged between the ATR crystal and the lens, wherein the optical window preferably contains or consists of zinc sulfide, and / or comprises at least one fourth sealing element arranged on an outer side of the module main body facing the flow cell, which is in sealing contact with a side of the flow cell facing the module main body, wherein the at least one fourth sealing element is designed in the form of a circular ring, and / or comprises a polarizer for polarizing a light beam reflected by the ATR crystal and subsequently coupled out.

[0150] Aspect B15:

[0151] Spectrometer comprising at least one light source, at least one light detector and an optical module according to one of aspects B12 to B14, wherein the spectrometer is preferably an FTIR spectrometer or a QCL-based infrared spectrometer.

[0152] The present invention is explained in more detail with reference to the following figures and examples, without limiting the invention to the specifically illustrated parameters.

[0153] Example 1

[0154] Figs. 1a to 1c show several views of a first exemplary embodiment of a flow cell according to the invention. Fig. 1a shows a top view of the flow cell 100. Fig. 1b shows a side sectional view of the flow cell 100, the section being taken along the line AA shown in Fig. 1a. Furthermore, Fig. 1c shows an exploded view of the flow cell.

[0155] The flow cell 100 comprises a polymeric base body 1 (e.g., made of the product "BioMed Clear" from the manufacturer formlabs) with an inlet 2 for substances to be measured and an outlet 3 for measured substances, as well as an aperture 4 arranged on a first outer side of the base body 1, which aperture is made of an alloy, e.g., stainless steel. The base body 1 and the aperture 4 are thus made of different materials that have different thermal expansion coefficients.

[0156] On the first outer side of the base body 1, a recess 5 is provided, which contains a flow cell measuring chamber fluidically connected to the inlet 2 and the outlet 3. The aperture 4 is arranged on the first outer side of the base body 1, on which the recess 5 containing the flow cell measuring chamber is also provided. Thus, the recess 5 with the flow cell measuring chamber borders the aperture 4. The aperture stop 6 is also formed in this area of ​​the aperture 4, so that the aperture stop 6 borders the recess 5.

[0157] Fig. 1d shows an enlarged section of Fig. 1b, which shows an enlarged lateral view of the recess 5 and the elements arranged therein. The flow cell 100 further comprises an arrangement consisting of an ATR crystal 7 and a first sealing element 8 for sealing the flow cell measuring chamber, which is clamped between the aperture 4 and a first wall region of the recess 5 facing the aperture 4. The first sealing element 8 is arranged on a side of the ATR crystal 7 facing away from the aperture 4 and is in sealing contact with the ATR crystal 7 and the first wall region of the recess 5. A central wall region of the recess facing the aperture 4 has an opening connected to one inlet 2 and an opening connected to the outlet 3.

[0158] The ATR crystal 7, which is made of silicon, for example, comprises several microprisms and has a structure 7a with V-shaped grooves or notches on a side facing the aperture. The first sealing element 8 is made of a polymeric material (e.g., ethylene propylene diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0159] The flow cell chamber is now configured such that it is defined by the ATR crystal 7, the sealing element 8, and wall regions of the recess 5. By fixing the aperture 4 to the base body 1, the assembly comprising the ATR crystal 7 and the sealing element 8 can be clamped between the aperture 4 and the first wall region of the recess 5, thereby sealing the flow cell chamber.

[0160] Here, the aperture 4 can be fixed to a first fixing point on the base body 1 via a first fixing means 9 and to a second fixing point via a second fixing means 10. The recess 5 is arranged between the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10), wherein the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10) are at the same distance from the recess 5. The first fixing means 9 is a countersunk head screw, and the second fixing means 10 is a lens head screw.By means of the countersunk head screw, the aperture 4 can be fixed at the first fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to one another at the first fixing point in an x-direction running parallel to the first outer side of the base body 1, in a y-direction running parallel to the first outer side of the base body 1 and in a z-direction running perpendicular to the first outer side of the base body 1.By means of the lens head screw, the aperture 4 can be fixed to the second fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to each other in the z-direction at the second fixing point and are only movable relative to each other to a limited extent in the x-direction and in the y-direction, so that different expansions and contractions of the components of the flow cell that occur when the temperature changes can be compensated.

[0161] As a result, in the event of a significant temperature change (e.g. during sterilization or autoclaving of the flow cell), there is a different expansion of the base body 1 and the aperture 4 (due to the different thermal expansion coefficients), but this does not lead to a bending of the components (due to a certain mobility in the x and y directions), so that the clamped arrangement comprising the ATR crystal 7 and the first sealing element 8 does not loosen. In this way, the formation of leaks in the arrangement at which the flow cell measuring chamber is no longer sufficiently sealed can be prevented. Therefore, the flow cell - even in the event of a significant temperature change (e.g. during sterilization or autoclaving of the flow cell) - has a high level of tightness, so that contaminants can no longer enter the flow cell chamber through leaks from the outside.As a result, contamination of the flow cell chamber and the substances measured therein by external contaminants or microorganisms can be better avoided.

[0162] The flow cell 100 additionally comprises a second sealing element 11 which is arranged around the recess 5, wherein the second sealing element consists of a polymeric material (e.g. ethylene-propylene-diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0163] Furthermore, the flow cell 100 comprises a single third fixing means 12 for attaching the flow cell to a module main body of an optical module. The third fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the third fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1. Here, the recess 5 is arranged between the second outer side of the base body 1 and the third fixing means 12. The aperture also additionally has a third sealing element 14 that is arranged around the at least one third fixing means and is sealingly connected to the third fixing means 12.

[0164] Example 2

[0165] Figs. 2a to 2c show several views of a second exemplary embodiment of a flow cell according to the invention. Fig. 2a shows a top view of the flow cell 100. Fig. 2b shows a side sectional view of the flow cell 100, taken along the line AA shown in Fig. 2a. Furthermore, Fig. 2c shows an exploded view of the flow cell.

[0166] The flow cell 100 comprises a polymeric base body 1 (e.g., made of the product "BioMed Clear" from the manufacturer formlabs) with an inlet 2 for substances to be measured and an outlet 3 for measured substances, as well as an aperture 4 arranged on a first outer side of the base body 1, which aperture is made of an alloy, e.g., stainless steel. The base body 1 and the aperture 4 are thus made of different materials that have different thermal expansion coefficients.

[0167] On the first outer side of the base body 1, a recess 5 is provided, which contains a flow cell measuring chamber fluidically connected to the inlet 2 and the outlet 3. The aperture 4 is arranged on the first outer side of the base body 1, on which the recess 5 containing the flow cell measuring chamber is also provided. Thus, the recess 5 with the flow cell measuring chamber borders the aperture 4. The aperture stop 6 is also formed in this area of ​​the aperture 4, so that the aperture stop 6 borders the recess 5.

[0168] Fig. 2d shows an enlarged section of Fig. 2b, which shows an enlarged lateral view of the recess 5 and the elements arranged therein. The flow cell 100 further comprises an arrangement consisting of an ATR crystal 7 and a first sealing element 8 for sealing the flow cell measuring chamber, which is clamped between the aperture 4 and a first wall region of the recess 5 facing the aperture 4. The first sealing element 8 is arranged on a side of the ATR crystal 7 facing away from the aperture 4 and is in sealing contact with the ATR crystal 7 and the first wall region of the recess 5. A central wall region of the recess facing the aperture 4 has an opening connected to one inlet 2 and an opening connected to the outlet 3.

[0169] The ATR crystal 7, which is made of silicon, for example, comprises several microprisms and has a structure 7a with V-shaped grooves or notches on a side facing the aperture. The first sealing element 8 is made of a polymeric material (e.g., ethylene propylene diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0170] The flow cell chamber is now configured such that it is defined by the ATR crystal 7, the sealing element 8, and wall regions of the recess 5. By fixing the aperture 4 to the base body 1, the assembly comprising the ATR crystal 7 and the sealing element 8 can be clamped between the aperture 4 and the first wall region of the recess 5, thereby sealing the flow cell chamber.

[0171] Here, the aperture 4 can be fixed to a first fixing point on the base body 1 via a first fixing means 9 and to a second fixing point via a second fixing means 10. The recess 5 is arranged between the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10), wherein the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10) are at the same distance from the recess 5. The first fixing means 9 is a countersunk head screw, and the second fixing means 10 is a lens head screw.By means of the countersunk head screw, the aperture 4 can be fixed at the first fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to one another at the first fixing point in an x-direction running parallel to the first outer side of the base body 1, in a y-direction running parallel to the first outer side of the base body 1 and in a z-direction running perpendicular to the first outer side of the base body 1.The lens-head screw allows the aperture 4 to be fixed to the second fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to one another in the z-direction at the second fixing point, and are only movable relative to one another to a limited extent in the x-direction and the y-direction, so that different expansions and contractions of the flow cell components that occur during temperature changes can be compensated. As a result, in the event of a significant temperature change (e.g. during sterilization orAlthough autoclaving the flow cell leads to a different expansion of the base body 1 and the aperture 4 (due to the different thermal expansion coefficients), this does not lead to a bending of the components (due to a certain mobility in the x and y directions), so that the clamped arrangement comprising the ATR crystal 7 and the first sealing element 8 does not become loose. In this way, the formation of leaks in the arrangement at which the flow cell measuring chamber is no longer sufficiently sealed can be prevented. Therefore, the flow cell has a high level of tightness - even in the event of significant temperature changes (e.g. when sterilizing or autoclaving the flow cell) - so that contaminants can no longer enter the flow cell chamber through leaks from the outside.As a result, contamination of the flow cell chamber and the substances measured therein by external contaminants or microorganisms can be better avoided.

[0172] The flow cell 100 additionally comprises a second sealing element 11 which is arranged around the recess 5, wherein the second sealing element consists of a polymeric material (e.g. ethylene-propylene-diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0173] Furthermore, the flow cell 100 comprises a single third fixing means 12 for attaching the flow cell to a module main body of an optical module. The third fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the third fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1. Here, the recess 5 is arranged between the second outer side of the base body 1 and the third fixing means 12. The aperture also additionally has a third sealing element 14 that is arranged around the at least one third fixing means and is sealingly connected to the third fixing means 12.

[0174] In addition, the flow cell 100 additionally comprises a filter element 15, which is arranged in the recess 5 between the ATR crystal 7 and the opening connected to the inlet 2, as well as between the ATR crystal 7 and the opening connected to the outlet 3. The filter element 15 can be, for example, a cellulose filter element with a thickness in the range of 0.02 mm to 0.2 mm.

[0175] The substances being measured, which are passed through the flow cell, may contain larger molecules (e.g., proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. This deposit or biofouling subsequently leads to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum, thus affecting the quality of the measurement. Furthermore, deposits on the ATR crystal can contaminate the substance being measured there in a subsequent measurement.

[0176] The filter element 15 can keep larger molecules (e.g. proteins), cell residues and microorganisms contained in the substances to be measured away from the ATR crystal 8, as these components are retained by the filter element 15, while the liquid with the smaller molecules relevant for the optical measurement passes through the filter element 15. As a result, deposits or biofouling on the ATR crystal 7 can be better avoided. Consequently, the filter element 15 can better prevent contamination of the flow cell chamber and also of the substances to be measured (in the future) therein. In addition, the filter element 15 can also keep gas bubbles present in the substances to be measured away from the ATR crystal 7, which, if they accumulate on the ATR crystal 7, would also lead to an undesired influence on the measurement or the measured spectrum.

[0177] Furthermore, the flow cell 100 additionally comprises a filter holder 16 for holding the filter element 15, which is arranged between the ATR crystal 7 and the filter element 15. The filter holder 16 has a grid structure and a frame extending around the grid structure. Preferably, the frame can be in contact with the ATR crystal 7, and the grid structure can not be in contact with the ATR crystal 7. For example, the grid structure can be arranged at a distance of 0.01 mm to 1 mm from the ATR crystal 7. The filter element 15 can preferably be clamped between the frame and a second wall region of the recess 5 facing the aperture 4. Preferably, the central wall region of the recess 5 facing the aperture 4 can have three holding elements, wherein the filter element 15 can be clamped between the grid structure and the holding elements.In addition, the central wall area of ​​the recess 5 can have a serrated structure, by means of which the risk of biofouling occurring on the filter element 15 can be reduced.

[0178] Example 3

[0179] Figs. 3a to 3c show several views of a third exemplary embodiment of a flow cell according to the invention. Fig. 3a shows a top view of the flow cell 100. Fig. 3b shows a side sectional view of the flow cell 100, taken along the line AA shown in Fig. 3a. Furthermore, Fig. 3c shows an exploded view of the flow cell.

[0180] The flow cell 100 comprises a polymeric base body 1 (e.g., made of the product "BioMed Clear" from the manufacturer formlabs) with an inlet 2 for substances to be measured and an outlet 3 for measured substances, as well as an aperture 4 arranged on a first outer side of the base body 1, which aperture is made of an alloy, e.g., stainless steel. The base body 1 and the aperture 4 are thus made of different materials that have different thermal expansion coefficients.

[0181] On the first outer side of the base body 1, a recess 5 is provided, which contains a flow cell measuring chamber fluidically connected to the inlet 2 and the outlet 3. The aperture 4 is arranged on the first outer side of the base body 1, on which the recess 5 containing the flow cell measuring chamber is also provided. Thus, the recess 5 with the flow cell measuring chamber borders the aperture 4. The aperture stop 6 is also formed in this area of ​​the aperture 4, so that the aperture stop 6 borders the recess 5.

[0182] Fig. 3d shows an enlarged section of Fig. 3b, which shows an enlarged lateral view of the recess 5 and the elements arranged therein. The flow cell 100 further comprises an arrangement consisting of an ATR crystal 7 and a first sealing element 8 for sealing the flow cell measuring chamber, which is clamped between the aperture 4 and a first wall region of the recess 5 facing the aperture 4. The first sealing element 8 is arranged on a side of the ATR crystal 7 facing away from the aperture 4 and is in sealing contact with the ATR crystal 7 and the first wall region of the recess 5. A central wall region of the recess facing the aperture 4 has an opening connected to one inlet 2 and an opening connected to the outlet 3.

[0183] The ATR crystal 7, which is made of silicon, for example, comprises several microprisms and has a structure 7a with V-shaped grooves or notches on a side facing the aperture. The first sealing element 8 is made of a polymeric material (e.g., ethylene propylene diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0184] The flow cell chamber is now configured such that it is defined by the ATR crystal 7, the sealing element 8, and wall regions of the recess 5. By fixing the aperture 4 to the base body 1, the assembly comprising the ATR crystal 7 and the sealing element 8 can be clamped between the aperture 4 and the first wall region of the recess 5, thereby sealing the flow cell chamber.

[0185] Here, the aperture 4 can be fixed to a first fixing point on the base body 1 via a first fixing means 9 and to a second fixing point via a second fixing means 10. The recess 5 is arranged between the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10), wherein the first fixing point (or the first fixing means 9) and the second fixing point (or the second fixing means 10) are at the same distance from the recess 5. The first fixing means 9 is a countersunk head screw, and the second fixing means 10 is a lens head screw.By means of the countersunk head screw, the aperture 4 can be fixed at the first fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to one another at the first fixing point in an x-direction running parallel to the first outer side of the base body 1, in a y-direction running parallel to the first outer side of the base body 1 and in a z-direction running perpendicular to the first outer side of the base body 1.By means of the lens head screw, the aperture 4 can be fixed to the second fixing point on the base body 1 in such a way that the base body 1 and the aperture 4 are essentially not movable relative to each other in the z-direction at the second fixing point and are only movable relative to each other to a limited extent in the x-direction and in the y-direction, so that different expansions and contractions of the components of the flow cell that occur when the temperature changes can be compensated.

[0186] As a result, in the event of a significant temperature change (e.g. during sterilization or autoclaving of the flow cell), there is a different expansion of the base body 1 and the aperture 4 (due to the different thermal expansion coefficients), but this does not lead to a bending of the components (due to a certain mobility in the x and y directions), so that the clamped arrangement comprising the ATR crystal 7 and the first sealing element 8 does not loosen. In this way, the formation of leaks in the arrangement at which the flow cell measuring chamber is no longer sufficiently sealed can be prevented. Therefore, the flow cell - even in the event of a significant temperature change (e.g. during sterilization or autoclaving of the flow cell) - has a high level of tightness, so that contaminants can no longer enter the flow cell chamber through leaks from the outside.As a result, contamination of the flow cell chamber and the substances measured therein by external contaminants or microorganisms can be better prevented. The flow cell 100 additionally comprises a second sealing element 11 arranged around the recess 5. The second sealing element is made of a polymeric material (e.g., ethylene propylene diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0187] Furthermore, the flow cell 100 comprises a single third fixing means 12 for attaching the flow cell to a module main body of an optical module. The third fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the third fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1. Here, the recess 5 is arranged between the second outer side of the base body 1 and the third fixing means 12. The aperture also additionally has a third sealing element 14 that is arranged around the at least one third fixing means and is sealingly connected to the third fixing means 12.

[0188] In addition, the flow cell 100 additionally comprises a filter element 15, which is arranged in the recess 5 between the ATR crystal 7 and the opening connected to the inlet 2, as well as between the ATR crystal 7 and the opening connected to the outlet 3. The filter element 15 is fastened to the first sealing element 8. It is integrally connected to the inner edge of the annular first sealing element 8, so that the (entire) area lying between the inner edge of the annular first sealing element 8 is closed by the filter element 15. The first sealing element 8 is thus arranged around the filter element 15 or runs along the edge of the filter element 15. The first sealing element 8 and the filter element 15 can also be regarded here as a common sealing-filter element. The filter element 15 can be, for example, a cellulose filter element having a thickness in the range of 0.02 mm to 0.2 mm.The filter element 15 is arranged in direct contact with at least one photoresist coating 16 applied to the ATR crystal. The photoresist coating 16 is applied in stripes to the ATR crystal, with the arrangement of the photoresist coating on the ATR crystal being adapted to the structuring 7a of the ATR crystal, which the ATR crystal has on the side facing the aperture. The photoresist coating can, for example, have a thickness in the range of 0.1 pm to 100 pm.

[0189] The substances being measured, which are passed through the flow cell, may contain larger molecules (e.g., proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. This deposit or biofouling subsequently leads to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum, thus affecting the quality of the measurement. Furthermore, deposits on the ATR crystal can contaminate the substance being measured there in a subsequent measurement.

[0190] The filter element 15 can keep larger molecules (e.g., proteins), cell debris, and microorganisms contained in the substances to be measured away from the ATR crystal 8, as these components are retained by the filter element 15, while the liquid containing the smaller molecules relevant for the optical measurement passes through the filter element 15. As a result, deposits or biofouling on the ATR crystal 7 can be better prevented. Consequently, the filter element 15 can better prevent contamination of the flow cell chamber and also of the substances to be measured (in the future). Furthermore, the filter element 15 can also keep gas bubbles present in the substances to be measured away from the ATR crystal 7, which, if they accumulate on the ATR crystal 7, would also lead to an undesired influence on the measurement or the measured spectrum. Embodiment 4

[0191] Fig. 4 shows a sectional view of an exemplary embodiment of a spectrometer according to the invention. This comprises an exemplary embodiment of an optical module 1000 according to the invention (indicated by the dashed frame in Fig. 4), which comprises a module main body 200 and an exemplary embodiment of a flow cell 100 according to the invention, which is attached to the module main body 200.

[0192] The module main body 200 comprises a lens 17 for coupling in a light beam incident on the ATR crystal 7 and for coupling out a light beam reflected by the ATR crystal 7, wherein the lens 17 is made of zinc selenide, for example. Furthermore, the module main body 200 comprises an optical window 18 arranged between the ATR crystal 7 and the lens 17, wherein the optical window 18 is made of zinc sulfide, for example. The module main body 200 also comprises a fourth sealing element 19 arranged on an outer side of the module main body 200 facing the flow cell 100, which sealing element is in sealing contact with a side of the flow cell 100 facing the module main body 200. The fourth sealing element 19 is in the form of a circular ring (O-ring).In addition, the module main body 200 comprises a polarizer 20 for polarizing a light beam reflected by the ATR crystal 7 and then coupled out, a motor 21 for rotating the polarizer 20 and two mirrors 22d, 22e.

[0193] The flow cell 100 is fastened to the module main body via a single third fixing means 12 and a stop element 23 arranged on an outer side of the module main body 200 facing the flow cell 100. The stop element 23 has a stop surface against which the flow cell 100 is pressed by the third fixing means 12. The third fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the third fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. The angle between the stop surface and the first outer side of the base body 1 also lies in a range of 40° to 50°.Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1, wherein the protruding region 13 is pressed against the stop surface of the stop element 23. The recess 5 is arranged between the second outer side of the base body 1 and the third fixing means 12.

[0194] The third fixing means 12 and the stop element 23 enable the flow cell 100 to be firmly connected to the module main body 200 in a simple manner. The third fixing means 12 is mounted at a specific angle to the first outer side of the base body 1, so that the flow cell 100 is pressed at a specific angle against the module main body 200 and against the stop surface of the stop element 23, i.e., a first force component is directed toward the module main body 200, and a second force component is directed toward the stop surface. The stop surface can then be arranged at a corresponding angle to the first outer side of the base body 1 in order to effectively absorb the force component exerted by the third fixing means 12 on the stop surface and redirect it to the module main body 200. In this way, a very firm fixation can be achieved.

[0195] The spectrometer further comprises a light source 24, a light detector 25, a beam splitter 26, three mirrors 22a, 22b, 22c and two parabolic mirrors 27a, 27b.

[0196] Example 5

[0197] Fig. 5 shows a sectional view of an exemplary embodiment of a spectrometer according to the invention. This includes an exemplary embodiment of an optical module 1000 according to the invention (indicated by the dashed frame in Fig. 5), which includes a module main body 200 and an exemplary embodiment of a flow cell 100 according to the invention, which is attached to the module main body 200.

[0198] The module main body 200 comprises a lens 17 for coupling in a light beam incident on the ATR crystal 11 7 and for coupling out a light beam reflected by the ATR crystal 7, wherein the lens 17 is made of zinc selenide, for example. Furthermore, the module main body 200 comprises an optical window 18 arranged between the ATR crystal 7 and the lens 17, wherein the optical window 18 is made of zinc sulfide, for example. The module main body 200 also comprises a fourth sealing element 19 arranged on an outer side of the module main body 200 facing the flow cell 100, which is in sealing contact with a side of the flow cell 100 facing the module main body 200. The fourth sealing element 19 is in the form of a circular ring (O-ring). In addition, the module main body 200 comprises two mirrors 22d, 22e.

[0199] The flow cell 100 is fastened to the module main body via a single third fixing means 12 and a stop element 23 arranged on an outer side of the module main body 200 facing the flow cell 100. The stop element 23 has a stop surface against which the flow cell 100 is pressed by the third fixing means 12. The third fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the third fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. The angle between the stop surface and the first outer side of the base body 1 also lies in a range of 40° to 50°.Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1, wherein the protruding region 13 is pressed against the stop surface of the stop element 23. The recess 5 is arranged between the second outer side of the base body 1 and the third fixing means 12.

[0200] The third fixing means 12 and the stop element 23 enable the flow cell 100 to be firmly connected to the module main body 200 in a simple manner. The third fixing means 12 is mounted at a specific angle to the first outer side of the base body 1, so that the flow cell 100 is pressed at a specific angle against the module main body 200 and against the stop surface of the stop element 23, i.e., a first force component is directed toward the module main body 200, and a second force component is directed toward the stop surface. The stop surface can then be arranged at a corresponding angle to the first outer side of the base body 1 in order to effectively absorb the force component exerted by the third fixing means 12 on the stop surface and redirect it to the module main body 200. In this way, a very firm fixation can be achieved.

[0201] The spectrometer further comprises a light source 24, two light detectors 25a, 25b, a spectrometer-internal polarizer 28, a beam splitter 26, four mirrors 22a, 22b, 22c, 22f and three parabolic mirrors 27a, 27b, 27c.

[0202] Example 6

[0203] Fig. 6 shows a part of another exemplary embodiment of a flow cell according to the invention in a side sectional view. In this embodiment, the flow cell comprises a filter element 15, which is arranged in the recess between the ATR crystal 7 and an opening connected to the inlet and / or between the ATR crystal 7 and an opening connected to the outlet. The filter element 15 is arranged in direct contact with a spacer 16 arranged, preferably applied, on the ATR crystal. For reasons of clarity, only the ATR crystal 7, the filter element 15 and the spacer 16 are shown in Fig. 6, i.e. all other elements of the flow cell are not shown in Fig. 6.The spacer 16 can be applied to the ATR crystal 7 in the form of a grid or in strip form, wherein the arrangement of the spacer 16 on the ATR crystal 7 is adapted to a structuring of the ATR crystal 7, which the ATR crystal 7 has on a side facing the aperture, in such a way that it is arranged only in those regions which, due to the structuring of the ATR crystal 7 (or the geometry of the structuring), are not reached (or illuminated) by optical beams 29 during an optical measurement. The light path is thus selected by the geometry of the ATR crystal 7 (or the geometry of the structuring) such that unilluminated regions arise on the upper side of the ATR crystal, wherein the spacer 16 is applied to these regions. The filter element 15 (e.g. in the form of a filter membrane) is applied to this spacer 16. The spacer 16 can be made by various methods, such aslithography, 3D printing, or CNC. For example, the spacer 16 can be a photoresist coating.

[0204] Example 7

[0205] In Fig. 7a, another exemplary embodiment of a flow cell according to the invention is shown in a side sectional view of the flow cell 100.

[0206] The flow cell 100 comprises a base body 1 with an inlet 2 for substances to be measured and an outlet 3 for measured substances as well as an aperture 4 arranged on a first outer side of the base body 1. The aperture 4 is attached (or glued) to the base body 1 by means of at least one adhesive.

[0207] The base body 1 and the aperture 4 can preferably be made of different materials with different thermal expansion coefficients. The base body 1 is preferably a polymer base body (e.g., the product "BioMed Clear" from the manufacturer formlabs). The aperture is preferably made of an alloy, e.g., stainless steel.

[0208] On the first outer side of the base body 1, a recess 5 is provided, which contains a flow cell measuring chamber fluidically connected to the inlet 2 and the outlet 3. The aperture 4 is arranged on the first outer side of the base body 1, on which the recess 5 containing the flow cell measuring chamber is also provided. Thus, the recess 5 with the flow cell measuring chamber borders the aperture 4. The aperture stop 6 is also formed in this area of ​​the aperture 4, so that the aperture stop 6 borders the recess 5.

[0209] Fig. 7b shows an enlarged section of Fig. 7a, which shows an enlarged lateral view of the recess 5 and the elements arranged therein. The flow cell 100 further comprises an arrangement consisting of an ATR crystal 7 and a first sealing element 8 for sealing the flow cell measuring chamber, which is clamped between the aperture 4 and a first wall region of the recess 5 facing the aperture 4. The first sealing element 8 is arranged on a side of the ATR crystal 7 facing away from the aperture 4 and is in sealing contact with the ATR crystal 7 and the first wall region of the recess 5. A central wall region of the recess facing the aperture 4 has an opening connected to the inlet 2 and an opening connected to the outlet 3.

[0210] The ATR crystal 7, which is made of silicon, for example, can comprise several microprisms and have a structure with V-shaped grooves or notches on a side facing the aperture. The first sealing element 8 is made of a polymeric material (e.g., ethylene propylene diene rubber or silicone) and is designed in the form of a circular ring (O-ring).

[0211] Furthermore, the flow cell 100 comprises a single fixing means 12 for attaching the flow cell to a module main body of an optical module. The fixing means 12 is a cylinder head screw. This is arranged such that the angle between the main extension direction of the cylinder head screw (or of the fixing means 12) and the first outer side of the base body 1 lies in a range of 40° to 65°. Furthermore, the aperture 4 has a protruding region 13 that protrudes beyond a second outer side of the base body 1 adjacent to the first outer side of the base body 1. Here, the recess 5 is arranged between the second outer side of the base body 1 and the fixing means 12. The aperture also has an additional sealing element 14 that is arranged around the fixing means 12 and is sealingly connected to the fixing means 12.

[0212] In addition, the flow cell 100 additionally comprises a filter element 15, which is arranged in the recess 5 between the ATR crystal 7 and the opening connected to the inlet 2, as well as between the ATR crystal 7 and the opening connected to the outlet 3. The filter element 15 can preferably be attached to the first sealing element 8. The filter element 15 can be, for example, a cellulose filter element with a thickness in the range of 0.02 mm to 0.2 mm.

[0213] The substances being measured, which are passed through the flow cell, may contain larger molecules (e.g., proteins), cell debris, and microorganisms. These can deposit on the ATR crystal, which can lead to biofouling. This deposit or biofouling subsequently leads to a deterioration of the measurement, as the deposited components lead to a disproportionately large signal in the measurement or the measured spectrum, thus affecting the quality of the measurement. Furthermore, deposits on the ATR crystal can contaminate the substance being measured there in a subsequent measurement.

[0214] The filter element 15 can keep larger molecules (e.g. proteins), cell residues and microorganisms contained in the substances to be measured away from the ATR crystal 8, as these components are retained by the filter element 15, while the liquid with the smaller molecules relevant for the optical measurement passes through the filter element 15. As a result, deposits or biofouling on the ATR crystal 7 can be better avoided. Consequently, the filter element 15 can better prevent contamination of the flow cell chamber and also of the substances to be measured (in the future) therein. In addition, the filter element 15 can also keep gas bubbles present in the substances to be measured away from the ATR crystal 7, which, if they accumulate on the ATR crystal 7, would also lead to an undesired influence on the measurement or the measured spectrum.

Claims

Patent claims 1. Flow cell (100) for optical measurements, comprising a base body (1) with at least one inlet (2) and at least one outlet (3) and an aperture (4) arranged on a first outer side of the base body (1), wherein a recess (5) is provided on the first outer side of the base body (1), which recess contains a flow cell measuring chamber connected to the at least one inlet (2) and the at least one outlet (3), wherein the flow cell (100) further comprises an arrangement comprising an ATR crystal (7) and at least one first sealing element (8) for sealing the flow cell measuring chamber, clamped between the aperture (4) and at least one first wall region of the recess (5), wherein the at least one first sealing element (8) is arranged on a side of the ATR crystal (7) facing away from the aperture (4), wherein the base body (1) consists of at least one material having a first thermal expansion coefficient has,and the aperture (4) consists of at least one material which has a second thermal expansion coefficient different from the first thermal expansion coefficient, wherein the aperture (4) can be fixed to at least one first fixing point on the base body (1) via at least one first fixing means (9) such that the base body (1) and the aperture (4) are essentially not movable relative to one another at the at least one first fixing point in an x-direction running parallel to the first outer side of the base body (1), in a y-direction running parallel to the first outer side of the base body (1) and in a z-direction running perpendicular to the first outer side of the base body (1), and, wherein the aperture can be fixed to at least one second fixing point on the base body (1) via at least one second fixing means (10) in such a way that the base body (1) and the aperture (4) are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and in the y-direction only to the extent that different expansions and / or contractions of the components of the flow cell (100) that occur during temperature changes can be compensated, and / or the flow cell (100) comprises at least one filter element (15) which is arranged in the recess (5) between the ATR crystal (7) and at least one opening connected to the at least one inlet (2) and / or between the ATR crystal (7) and at least one opening connected to the at least one outlet (3).

2. Flow cell (100) according to the preceding claim, characterized in that the aperture (4) can be fixed to the at least one second fixing point on the base body (1) via the at least one second fixing means (10) in such a way that the base body (1) and the aperture (4) are essentially not movable relative to one another in the z-direction at the at least one second fixing point and are movable relative to one another in the x-direction and in the y-direction by at least 0.01 mm, preferably at least 0.05 mm, particularly preferably at least 0.1 mm, and / or by at most 1 mm, preferably at most 0.8 mm, particularly preferably at most 0.5 mm.

3. Flow cell (100) according to one of the preceding claims, characterized in that the at least one first fixing means (9) is selected from the group consisting of countersunk head screws, as well as combinations thereof, wherein the at least one first fixing means (9) is preferably at least one countersunk head screw, and / or the at least one second fixing means (10) is selected from the group consisting of lens head screws, rivets, cylinder head screws, as well as combinations thereof, wherein the at least one first fixing means (10) is preferably at least one lens head screw.

4. Flow cell (100) according to one of the preceding claims, characterized in that the at least one material from which the base body (1) is made is at least one polymer, which is preferably selected from the group consisting of polyetheretherketones, polytetrafluoroethylene, polypropylene, polysulfones, polyethersulfones, polycarbonates, polyvinyl chlorides, polylactides, polyamides, thermoplastic polyurethanes, acrylonitrile-butadiene-styrene, UV-curing synthetic resins, and mixtures thereof, and / or the at least one material from which the aperture (4) is made is selected from the group consisting of metals, e.g. iron; alloys, preferably iron-containing alloys, e.g. stainless steel; polymers, e.g. polyetheretherketones; and mixtures and combinations thereof, wherein the aperture (4) preferably contains or consists of stainless steel.

5. Flow cell (100) according to one of the preceding claims, characterized in that the ATR crystal (7) contains or consists of at least one material which is at least partially transparent to light with a wavelength in the range from 2 pm to 20 pm, preferably from 4 pm to 12 pm, wherein the ATR crystal (7) preferably contains or consists of at least one material which is selected from the group consisting of silicon, diamond, germanium, zinc selenide, zinc sulfide, and mixtures and combinations thereof, wherein the ATR crystal particularly preferably contains or consists of silicon, and / or comprises a plurality of microprisms, and / or has a structuring (7a) on a side facing the aperture, preferably structuring (7a) with grooves or grooves.

6. Flow cell (100) according to one of the preceding claims, characterized in that the at least one first sealing element (8) • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or • is designed in the form of a circular ring, and / or • is in sealing contact with the ATR crystal (7) and / or the at least one first wall region of the recess (5) and / or the flow cell (100) comprises at least one second sealing element (11) which is arranged around the recess (5), wherein the at least one second sealing element (11) is preferably • contains or consists of at least one polymer selected from the group consisting of ethylene-propylene-diene rubbers, silicones, and mixtures thereof, and / or • is designed in the form of a circular ring, and / or • at least partially in a recess (5) arranged around the first outer side of the base body (1) provided further recess, and / or • is in sealing contact with the base body (1) and / or the aperture (4).

7. Flow cell (100) according to one of the preceding claims, characterized in that the at least one filter element (15) is selected from the group consisting of cellulose filter elements, e.g. made of regenerated cellulose; paper filter elements; glass fiber filter elements; cellulose acetate filter elements; polyethersulfone filter elements; nylon filter elements; polyvinylidene fluoride filter elements; polytetrafluoroethylene filter elements; polypropylene filter elements; polycarbonate filter elements; and combinations thereof, wherein the at least one filter element is preferably selected from the group consisting of cellulose filter elements, paper filter elements, glass fiber filter elements, and combinations thereof, and / or has a thickness in the range from 0.001 mm to 5 mm, preferably from 0.01 mm to 1 mm, particularly preferably from 0.02 mm to 0.2 mm.

8. Flow cell (100) according to one of the preceding claims, characterized in that the flow cell (100) additionally comprises at least one filter holder (16) for holding the at least one filter element (15), which is arranged between the ATR crystal (7) and the at least one filter element (15), wherein the at least one filter holder (16) preferably has a grid structure and a frame running around the grid structure, wherein the frame is in contact with the ATR crystal (7) and the grid structure is not in contact with the ATR crystal (7), wherein the grid structure is preferably at a distance of 0.001 mm to 5 mm, preferably from 0.005 mm to 2 mm, particularly preferably from 0.008 mm to 1 mm, very particularly preferably from 0.01 mm to 0.1 mm, to the ATR crystal (7), and / or the at least one filter element (15) is clamped between the frame and at least one second wall region of the recess (5) facing the aperture (4), and / or a central wall region of the recess (5) facing the aperture (4) has at least one holding element, preferably at least two holding elements, wherein the at least one filter element (15) is clamped between the grid structure and the at least one holding element.

9. Flow cell (100) according to one of claims 1 to 7, characterized in that the at least one filter element (15) is arranged in direct contact with at least one photoresist coating (16) applied to the ATR crystal (7), wherein preferably the at least one photoresist coating (16) has a thickness in the range from 0.1 pm to 100 pm, preferably from 1 pm to 50 pm, particularly preferably from 5 pm to 20 pm, and / or the at least one photoresist coating (16) is applied in the form of a grid or strip-shaped on the ATR crystal (7), wherein the arrangement of the photoresist coating (16) on the ATR crystal (7) is preferably adapted to a structuring of the ATR crystal (7) which the ATR crystal (7) has on a side facing the aperture (4), and / or the at least one filter element (15) is attached to the at least one first sealing element (8) is fastened, preferably is materially connected to the at least one first sealing element (8).

10. Flow cell (100) according to one of the preceding claims, characterized in that the recess (5) is arranged between the at least one first fixing point and the at least one second fixing point, wherein the at least one first fixing point and the at least one second fixing point preferably have the same distance from the recess (5), and / or has a structuring, preferably a serrated structuring, on a central wall region of the recess (5) facing the aperture (4), and / or has at least one opening connected to the at least one inlet (2) on a central wall region of the recess (5) facing the aperture (4), and / or has at least one opening connected to the at least one outlet (3) on a central wall region of the recess (5) facing the aperture (4).

11. Flow cell (100) according to one of the preceding claims, characterized in that the flow cell (100) comprises at least one third fixing means (12), preferably a single third fixing means (12), for fastening the flow cell (100) to a module main body of an optical module, wherein the at least one third fixing means (12) has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body (1) lies in a range from 20° to 85°, preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means (12) is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least one third fixing means (12) is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw,and / or the aperture (4) has a projecting region (13) which projects beyond a second outer side of the base body (1), where-, wherein the recess (5) is preferably arranged between the second outer side of the base body (1) and the at least one third fixing means (12), and / or the flow cell (100) additionally has at least one third sealing element (14) which is arranged around the at least one third fixing means (12) and is sealingly connected to the at least one third fixing means (12).

12. An optical module (1000) comprising a module main body (200) and a flow cell (100) according to any one of the preceding claims, which is attached to the module main body.

13. Optical module (1000) according to claim 12, characterized in that the flow cell (100) is fastened to the module main body (200) via at least one third fixing means (12), preferably a single third fixing means (12), as well as a stop element (23) arranged on an outer side of the module main body (200) facing the flow cell (100), wherein the stop element (23) has a stop surface against which the flow cell (100) is pressed by the at least one third fixing means (12), and wherein preferably an angle between the stop surface and the first outer side of the base body (1) lies in a range from 20° to 85°, preferably from 30° to 65°, particularly preferably from 40° to 50°, and / or the at least one third fixing means (12) has a main extension direction, wherein an angle between this main extension direction and the first outer side of the base body (1) in a range of 20° to 85°,preferably from 30° to 70°, particularly preferably from 40° to 65°, and / or the at least one third fixing means (12) is selected from the group consisting of cylinder head screws, lens head screws, and combinations thereof, wherein the at least, a third fixing means (12) is preferably at least one cylinder head screw, particularly preferably a single cylinder head screw, and / or the aperture (4) has a protruding region (13) which protrudes beyond a second outer side of the base body (1), wherein the protruding region (13) is pressed against the stop surface, and wherein the recess (5) is preferably arranged between the second outer side of the base body (1) and the at least one third fixing means (12), and / or the flow cell (100) additionally has at least one third sealing element (14) which is arranged around the at least one third fixing means (12).

14. Optical module (1000) according to claim 12 or 13, characterized in that the module main body (200) comprises a lens (17) for coupling in a light beam incident on the ATR crystal (7) and for coupling out a light beam reflected by the ATR crystal (7), wherein the lens (17) preferably contains or consists of zinc selenide, and / or comprises an optical window (18) which is arranged between the ATR crystal (7) and the lens (17), wherein the optical window (18) preferably contains or consists of zinc sulfide, and / or comprises at least one fourth sealing element (19) arranged on an outer side of the module main body (200) facing the flow cell (100), which is in sealing contact with a side of the flow cell (100) facing the module main body (200), wherein the at least one fourth sealing element (19) is preferably in the form of a circular ring,and / or a polarizer (20) for polarizing a light beam reflected by the ATR crystal (7) and subsequently coupled out., 5. Spectrometer comprising at least one light source, at least one light detector and an optical module (1000) according to one of claims 12 to 14, wherein the spectrometer is preferably an FTIR spectrometer or a QCL-based infrared spectrometer.

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