Membrane component for an ATR measuring element, ATR sensor having such a membrane component, and method for arranging the membrane component on an ATR sensor base assembly

Abstract

The invention relates to a membrane component (79) for arrangement on an ATR measuring element (24) conducting a measurement radiation at a distance from a sensor surface (26) of the ATR measuring element (24) intended to form an evanescent field, wherein the membrane component (79) comprises: - a membrane (84) which is permeable to a target liquid (ZF) and is made of a membrane material (83), and - a sacrificial component (86) which is arranged on one side of the membrane (84) and is formed from a sacrificial material (87) which is different from the membrane material (83) and is soluble by the target liquid (ZF).

Description

[0001] 68581 P WO Hamilton Bonaduz AG

[0002] - 1 -

[0003] Membrane component for an ATR measuring element, ATR sensor with such a membrane component and method for arranging the membrane component on an ATR sensor base assembly

[0004] Description

[0005] The present invention relates to a membrane component. The membrane component is suitable and intended for arrangement on an ATR measuring element. In an ATR sensor, the ATR measuring element serves to guide a measurement radiation by total internal reflection. A surface of the ATR measuring element, along which the measurement radiation is guided within the ATR measuring element, is intended as the sensor surface of the ATR measuring element for generating an evanescent field for measurement purposes. The membrane component comprises a membrane made of a membrane material that is permeable to a target liquid. The membrane is intended to be arranged at a distance from the sensor surface.

[0006] An ATR sensor with an ATR measuring element is fundamentally known from US 2021 / - 165123 A1. "ATR" stands for "Attenuated Total Reflection," a measurement principle based on attenuated total reflection. This measurement principle is generally known. The physical properties and operating principles used by this measurement principle to gain insights, as well as their metrological application, are very well explained in German patent DE 103 16 514 A1, to whose description reference is made here for the explanation of the measurement principle.

[0007] Other ATR sensors are known, for example, from US 7,593,107 B2 and EP 3 026 426 A1. These known ATR sensors use infrared radiation as the measuring radiation and include an infrared measuring sensor for detecting the attenuated measuring radiation in the evanescent field and an infrared reference sensor to provide a comparison scale for the signal of the infrared measuring sensor. 68581 P WO Hamilton Bonaduz AG

[0008] - 2 -

[0009] An ATR sensor of the applicant is known from DE 10 2022 114 935 A1. This known ATR sensor has a membrane as described above, which, however, is intended to lie directly on the sensor surface.

[0010] The ATR sensor is typically used for the metrological analysis of a fluid. Particularly in the application area of ​​fermentation technology, which is also the preferred application for the subject matter of the present application, the fluid under investigation may contain suspended particles or solids that could interfere with the measurement result of the ATR sensor if they enter the detection range of the ATR measuring element. Such suspended particles can be, for example, cell membranes or cell membrane fragments originating from dead and / or damaged cells in the cell-suspending target liquid. To prevent unwanted suspended particles or solids from interfering with the measurement result of the ATR sensor, the aforementioned membrane is arranged on an ATR sensor base assembly, extending over the sensor area of ​​the ATR measuring element.The membrane is permeable to the fluid being measured, but not to solids contained in the fluid, such as the aforementioned suspended particles.

[0011] An ATR sensor base assembly comprises at least one sensor housing, the ATR measuring element, a measuring radiation source emitting the measuring radiation, and a measuring sensor that responds to the measuring radiation emitted by the measuring radiation source. The ATR sensor base assembly may include, within the sensor housing, further sensors as well as evaluation electronics for processing signals from the at least one measuring sensor and / or control electronics for controlling the measuring radiation source and, optionally, the at least one measuring sensor. Furthermore, the ATR sensor base assembly may include transmission and / or connection means for transmitting signals between a higher-level data processing unit and the ATR sensor base assembly and / or for connecting signal transmission lines. These signal transmission lines can then, in turn, be used to transmit signals between a higher-level data processing unit and the ATR sensor base assembly.A transmission device can be a transmitting / receiving device or just a transmitting device. 68581 P WO Hamilton Bonaduz AG.

[0012] - 3 -

[0013] For the purposes of this application, a "membrane" is understood, according to the generally accepted definition, to be a planar layered body which, compared to its dimensions in two mutually orthogonal principal directions defining a membrane surface, has a significantly smaller thickness. Typically, a membrane of the present application has dimensions of at least several millimeters along each of its principal directions, while the thickness of the membrane is less than 1 mm, in particular less than 0.1 mm.

[0014] The membrane can be dimensionally unstable, meaning it can deform more than negligibly under its own weight. Conversely, the membrane can also be dimensionally stable and, although it inevitably deforms under its own weight due to its finite modulus of elasticity, this deformation is negligible. The membrane can also be elastically deformable under the influence of forces that occur during normal operation, including pre-assembly of the membrane on an ATR sensor base assembly.

[0015] WO 97 / 49985 A1 discloses an ATR sensor with a membrane, which is intended to detect partial pressures of gases dissolved in a liquid. In one embodiment described therein, the membrane is arranged at a distance from the sensor surface to form a detection chamber. The reason for this is that spectroscopic properties of the membrane material used, such as polytetrafluoroethylene, silicone, or fluoride polymers in general, react with the measurement radiation to interfere with or adversely affect the desired measurement of the dissolved gas.

[0016] WO 97 / 49985 A1 proposes, in the event of undesirable interference with the ATR measurement by the membrane material, to leave a gap on the order of a few wavelengths of the measurement radiation used between the membrane and the ATR measuring element and to fill this gap with an unspecified chemically and biologically inert fluid. This prevents the evanescent field formed at the sensor surface from affecting the membrane during sensor operation. 68581 P WO Hamilton Bonaduz AG

[0017] - 4 - achieve. The chemically and biologically inert fluid, which is only generally mentioned, must be selected according to the teachings of WO 97 / 49985 A1 according to the dissolved gas to be measured, because the gas to be measured is to diffuse through the membrane into the chemically and biologically inert fluid and be absorbed by it. Instead of being detected in its original solvent, the gas is detected in the chemically and biologically inert fluid. From the known membrane properties, as well as from the diffusion and absorption properties of the original solvent on the one hand and the chemically and biologically inert fluid arranged in the detection chamber on the other, conclusions can be drawn about the partial pressure of the measured gas in its original solvent.

[0018] One problem with the membrane ATR sensors described above is that the basic ATR sensor assembly is relatively expensive due to the high-quality technical and electronic components it contains, and is therefore reused for multiple measurement cycles. In contrast, the membrane is replaced after each measurement to prevent contamination of the next liquid to be measured between measurements in different containers or liquids, based on impurities from a previously measured liquid.

[0019] When attaching a new membrane to the ATR sensor base assembly, unwanted air inclusions can occur between the membrane and the sensor surface. These air inclusions prove stable during measurement, meaning that air bubbles trapped between the membrane and the sensor surface are not displaced by the target liquid, even over extended periods. The air inclusions inevitably lead to a distorted measurement result, as the evanescent field generated at the sensor surface cannot be attenuated by the target liquid in the area of ​​the air inclusions.

[0020] A temporary application of an auxiliary fluid, such as sterile water, between the membrane and the sensor surface does not reliably prevent air or gas exposure. 68581 P WO Hamilton Bonaduz AG

[0021] - 5 - inclusions to be avoided, because sterilization prior to trade fair operation eliminates such auxiliary fluids, usually by evaporation.

[0022] The object of the present invention is to provide a technical teaching which improves the accuracy of the measurement result achievable with ATR sensors with replaceable membranes without compromising the hygiene of the ATR sensor and its measurement environment.

[0023] This problem is solved according to the present invention by a membrane component with the features of claim 1. In addition to the membrane mentioned above, such a membrane component has a sacrificial component arranged on one side of the membrane, which is made of a sacrificial material different from the membrane material. The sacrificial material is selected such that it is soluble in the target fluid. For better understanding, the membrane component is described below in the context of its application to an ATR sensor. The advantages of the ATR sensor with a membrane component of the present application highlighted therein are also further developments of the ATR sensor of the present application presented below.

[0024] The membrane component is a component that can be manufactured and traded independently of an ATR sensor base assembly.

[0025] Preferably, the sacrificial material is selected to be inert with respect to the target liquid such that no chemical and / or biological reactions occur between the sacrificial material and the target liquid, at least for the duration of the measurement process, or only negligible ones. If the target liquid is a suspension liquid for living cells or active biological material, the sacrificial material is also selected with respect to the living cells or active biological material such that the sacrificial material does not affect the living cells or active biological material, or only to a negligible extent, at least for the duration of the measurement process. 68581 P WO Hamilton Bonaduz AG

[0026] - 6 -

[0027] The sacrificial component formed from the sacrificial material exists as a solid with a defined shape at a predetermined storage temperature; otherwise, it could not be considered a sacrificial component. This significantly simplifies the transport and handling of the membrane component along with the sacrificial component. Furthermore, it ensures that the sacrificial component is available until the membrane component is used on an ATR sensor. The sacrificial component can also be formed, either by initial shaping or reshaping, into a suitable shape for its placement on the ATR sensor base component, a shape which the sacrificial component retains until it melts or softens again.

[0028] The solubility of the sacrificial material in the target fluid allows the sacrificial material located between the sensor surface and the membrane to be replaced by the target fluid itself when the membrane component is ready for use and mounted on an ATR sensor base assembly. The target fluid can then pass through the membrane to reach the sacrificial material and dissolve or break it down.

[0029] In the ready-to-use state of the membrane component arranged on the ATR sensor base assembly, a gap is formed between the membrane and the sensor surface, which is delimited on opposite sides once by the membrane and once by the sensor surface from the external environment of the ready-to-use ATR sensor.

[0030] If necessary, the target liquid in the external environment of the ready-to-use ATR sensor can also reach and dissolve the sacrificial material located in the gap space via open edge areas of the gap space. Preferably, in the ready-to-use state of the ATR sensor with membrane component, the gap space is only accessible to the target liquid through the membrane, in order to prevent unwanted suspended particles from entering the vicinity of the sensor surface and thus the evanescent field relevant for measurement accuracy via an open edge area. 68581 P WO Hamilton Bonaduz AG

[0031] - 7 -

[0032] The concentration gradient of sacrificial material dissolved in the target liquid between the membrane and the sensor surface on the one hand, and on the opposite side of the membrane on the other, initiates and maintains diffusion processes that ensure sufficient dilution of the dissolved sacrificial material in the area between the membrane and the sensor surface. Through these diffusion processes, the dissolved sacrificial material in the gap can be exchanged for pure target liquid, at least through the membrane, and possibly also through the open edge regions of the gap.

[0033] The volume of such a gap is negligibly small compared to the volume of the external environment of the operational ATR sensor. The volume of the gap can be, for example, between 20 mm². 3 and 150 mm 3 The volume is such that at least half a liter of target liquid, i.e., at least 500,000 mm³, is often present around the operational ATR sensor.3 , but usually considerably more. Therefore, sufficient target fluid is always available during the dissolution of the sacrificial material to continue the dissolution process. Tests have shown that, through diffusion, the sacrificial material present in the gap is dissolved by the target fluid reaching it within approximately one hour and thus completely replaced by the target fluid, allowing a meaningful measurement to begin. In this way, a ready-to-use ATR sensor can become an operational ATR sensor capable of performing the desired measurement on the target fluid within one hour.

[0034] For the purposes of this application, an ATR sensor and its components are considered "ready for use" when the ATR sensor or its components are fully configured and positioned at the intended measurement location, and thus ready for use. This could, for example, be the arrangement of the ATR sensor in a holder of a vessel, in particular a fermentation reactor. However, the fully configured ATR sensor, positioned at the measurement location and therefore ready for use, may still contain sacrificial material in the gap between the membrane and the sensor surface, meaning that while the ATR sensor is ready for use, it is not yet operational for performing the desired measurement. Operational readiness is achieved when the gap immediately adjacent to the sensor surface is filled with sufficient material. 68581 P WO Hamilton Bonaduz AG

[0035] - 8 - The target liquid is filled, thus enabling the ATR sensor to produce a meaningful measurement result. The target liquid is always different from the sacrificial material.

[0036] If the ready-to-use membrane is arranged at a distance from the outer surface acting as the measuring surface, this distance is preferably larger, and particularly preferably many times larger, than the dimension extending in the distance direction of an evanescent field forming on the outer surface during measurement operation, in order to avoid influencing the evanescent field through the membrane.

[0037] Preferably, the sacrificial material has a melting point or a softening point that is higher than 23 °C.

[0038] The softening temperature is preferably a Vicat softening temperature A according to DIN EN ISO 306, measured at a test load of 10 Newtons.

[0039] For a crystalline or semi-crystalline sacrificial material that has a melting point due to its molecular structure, this melting point must be used. For a purely amorphous sacrificial material, in the absence of a melting point, the softening point, in particular the Vicat softening point A, measured at a test load of 10 N, must be used. For the entire present application, the aforementioned Vicat softening point A with a test load of 10 N is considered the preferred softening point.

[0040] The preferred melting or softening temperature ensures that the sacrificial material and the resulting sacrificial component exist as a solid at normal room temperature. This further simplifies the transport and handling of the membrane component, as it can be stored, transported, and provided without refrigeration in rooms with normal room temperatures.

[0041] Preferably, the melting temperature of the sacrificial material, if present, is lower than the lower of the melting and softening temperatures of the membrane material. Equally preferred is the softening temperature of the 68581 P WO Hamilton Bonaduz AG

[0042] - 9 -

[0043] The sacrificial material, if present, is at a lower temperature than the lower of the melting and softening temperatures of the membrane material. This ensures that the sacrificial material can be liquefied or sufficiently softened for a ready-to-use arrangement of the membrane on an ATR sensor base assembly, while the membrane retains its shape. Thus, relative to the volume of the ready-to-use gap between the membrane and the sensor surface, the sacrificial component on the membrane can be provided with an excess of sacrificial material to ensure that the sacrificial material, in its molten and / or softened state, is sufficient to fill the gap volume of the ready-to-use gap as completely as possible, thereby preventing unwanted air inclusions.

[0044] When arranging the membrane component or membrane on an ATR sensor base assembly to form a ready-to-use ATR sensor, the shape of the sacrificial component is dissolved by melting or softening, and excess sacrificial material is removed from the membrane component and the ATR sensor base assembly.

[0045] The membrane material can comprise or be polytetrafluoroethylene, in particular water-wettable polytetrafluoroethylene, so-called "wwPTFE," and / or silicone and / or polyetheretherketone and / or a fibrous material. The membrane material can be a ceramic material. Preferably, the membrane material is a polymer. In contrast to the sacrificial material, it is preferably not soluble in the target fluid. Preferably, the membrane is a flat membrane, at least in the operational state. Preferably, the membrane of the membrane component is a flat membrane before the membrane component or the membrane is attached to an ATR sensor base assembly. During the transition of the membrane component to a ready-to-use and subsequently operational state, the membrane may be elastically deformed due to the forces acting upon it. More detailed explanations follow below.

[0046] For typical applications in the field of bio-fermentation or in biological reactors, the membrane can have a thickness in the range of 0.03 mm to 0.3 mm, in particular from 0.15 mm to 0.25 mm, and can have a mean pore size of 68581 P WO Hamilton Bonaduz AG

[0047] - 10 - size from 0.03 pm to 0.75 pm, preferably from 0.35 pm to 0.55 pm, particularly preferably from 0.45 pm. However, these are only exemplary values ​​for a preferred application.

[0048] The membrane can be single-layered or multi-layered. In the case of a multi-layered design, the membrane can comprise different materials, which can be, for example, co-extruded or laminated by the intermediate placement of an adhesive. However, due to the desired porosity of the membrane as a whole, adhesive lamination of at least two layers is not preferred. Since the membrane of the membrane component is preferably used only as a separator to keep suspended particles in the target liquid away from the sensor surface, a single-layer membrane, which is advantageously easy to manufacture, is sufficient.

[0049] In principle, it is conceivable to arrange a sacrificial component on each side of the membrane, for example, to prevent errors in the arrangement of the membrane component on an ATR sensor base assembly due to incorrect orientation of the membrane component. However, this increases the amount of sacrificial material that must be removed from the membrane component to make it and the supporting ATR sensor base assembly operational. Therefore, the sacrificial component is preferably arranged predominantly, or more preferably, only on one side of the membrane.

[0050] The sacrificial component can be injection molded onto the membrane or cast onto the membrane at ambient pressure, due to the ability of the sacrificial material to melt or soften and further due to the porosity of the membrane and / or due to the compatibility of the membrane material and the sacrificial material.

[0051] An important property for ATR sensors used in biotechnology is their sterilizability. Sterilization of ATR sensors is preferably carried out thermally in an autoclave and / or with steam. To advantageously extend the sterilization process of an ATR sensor with a membrane component attached to its ATR sensor base assembly to include the melting or softening of the membrane component, see 68581 P WO Hamilton Bonaduz AG.

[0052] - 11 -

[0053] In order to be able to use sacrificial material, according to a preferred embodiment of the present invention, the sacrificial material is selected such that its melting temperature or its softening temperature is lower than 120 °C.

[0054] Preferably, the sacrificial material is selected such that it does not boil at least at temperatures below 140 °C. If the sacrificial material boils at excessively low temperatures, it may evaporate before the target fluid reaches the sensor surface. This again creates the risk of unwanted gas inclusions between the sensor surface and the membrane.

[0055] Sterilization processes for ATR sensors typically take place at temperatures that do not fall below 120 °C. Conversely, the temperatures acting on the ATR sensors during their sterilization process generally do not exceed 140 °C.

[0056] Immediately after the membrane component is positioned on the ATR measuring element and before the sacrificial component is heated, the sacrificial component, which is still present as a solid and usually lies against the sensor surface, acts as a proximity barrier or spacer, which physically prevents the membrane from approaching the sensor surface any further.

[0057] To facilitate the removal of excess sacrificial material from the ready-to-use ATR sensor, the sealing or softening temperature of the sacrificial material can be set within a temperature range of 50 °C to 80 °C using a membrane from the membrane component. This ensures that, on the one hand, the sacrificial component remains a solid even at elevated ambient temperatures, and on the other hand, that excessively high temperatures do not need to be applied to the sensor to quickly and reliably transform the sacrificial material into a flowable state.

[0058] Of course, the thermal energy required for liquefaction can also be supplied by suitable heat sources outside of a sterilization process. Utilizing the thermal energy of the sterilization process 68581 P WO Hamilton Bonaduz AG

[0059] - 12 - also for liquefying the sacrificial component, but advantageously reduces the energy required to make the ATR sensor ready for use.

[0060] The target liquid is preferably water, which is used in biological and biotechnological processes as the main component of suspension liquids or even as the suspension liquid itself.

[0061] A preferred sacrificial material is, for example, a polyolefin glycol. The sacrificial material is therefore preferably polyalkylene glycol and / or polyethylene glycol and / or polypropylene glycol. Additionally or alternatively, the sacrificial material may comprise a polyethylene-polypropylene glycol copolymer.

[0062] Different molecular weights of polyolefin glycol, particularly the preferred polyethylene glycol, are available on the market. In principle, all types of such glycol can be used as sacrificial materials. However, polyethylene glycol with a molar mass in the range of 3000 g / mol to 8000 g / mol, particularly preferably in the range of 3900 g / mol to 6000 g / mol, and most preferably 4000 g / mol, is preferred as the sacrificial material. Molecular weights that are too low lead to the sacrificial material beginning to flow even at temperatures only slightly above room temperature, resulting in undesirable deformation of the sacrificial component during handling of the membrane component. Furthermore, the water solubility of polyethylene glycol increases at higher temperatures as its molecular weight decreases.For the preferred melting of polyethylene glycol by steam sterilization, if polyethylene glycol with too low a molecular weight is used, the sacrificial material may be completely removed too early during steam sterilization. With increasing molecular weight of polyethylene glycol, its water solubility decreases. The aforementioned preferred range of polyethylene glycol as a sacrificial material represents an excellent compromise between stability in the supply of membrane components as replacement or consumable parts for ATR sensors on the one hand, and simple, reliable, and rapid processing to provide a ready-to-use ATR sensor on the other. 68581 P WO Hamilton Bonaduz AG.

[0063] - 13 -

[0064] The sacrificial material, in particular the preferred polyethylene glycol, can comprise poly(alkylene glycol) methyl ether or poly(alkylene glycol) dimethyl ether as a plasticizer to make the sacrificial material more ductile and less brittle. This facilitates crack-free deformation, in particular forming, of the sacrificial material into a desired shape.

[0065] To provide sufficient sacrificial material to fill the gap between the membrane and the sensor surface, the sacrificial component preferably has a greater thickness than the membrane in a common thickness direction. For example, in a preferred embodiment, the membrane can have a thickness in the range of 30 pm to 300 pm. Likewise, in a preferred embodiment, the sacrificial component can have a thickness in the range of 300 to 1000 pm. If the sacrificial component has different thicknesses along its extent in the principal directions of extension of the membrane, the greatest thickness of the sacrificial component is decisive.

[0066] To seal the gap at the ATR sensor, the sensor surface can be surrounded by a frame of a sensor housing and recessed relative to the surface of the surrounding frame. Preferably, the diaphragm rests against the frame when the ATR sensor is operational, so that the thickness of the frame determines the distance between the diaphragm and the sensor surface, and thus the thickness or depth of the gap. In this case, the sacrificial component can have a thicker inner part, which, when the diaphragm component is mounted on an ATR sensor base assembly, comes into contact with the sensor surface, and a thinner outer part, which surrounds the thicker inner part and, when the diaphragm component is mounted on an ATR sensor base assembly, faces the frame surrounding the sensor surface.The thinner outer part can be positioned at a distance from the frame immediately after a membrane component is attached to the ATR sensor base assembly and before it is heated. 68581 P WO Hamilton Bonaduz AG.

[0067] - 14 -

[0068] Preferably, the depth of the gap space in the ready-to-use and in the operational state of an ATR sensor is the same and preferably between 300 pm and 700 pm.

[0069] To ensure its ability to keep suspended particles away from the sensor surface while allowing the target liquid to pass through, the membrane preferably has pores. If such pores are present, they provide a pore volume within the membrane. Without further measures, the pores may initially be filled with gas, particularly air, when the membrane component is mounted on an ATR sensor base assembly. To prevent the air present in the pore volume of the membrane component from adversely affecting a subsequent measurement result of an ATR sensor equipped with the membrane component, it is possible to fill the pore volume at least partially, preferably completely, with sacrificial material. For this purpose, the membrane can be immersed in liquid sacrificial material for a predetermined duration during the manufacturing of the membrane component until it is fully saturated with the liquid sacrificial material.

[0070] In principle, the membrane component can consist only of the membrane and the sacrificial component. In this case, an ATR sensor base assembly using the membrane component can have a holder component into which the membrane component is inserted or clamped, or by which the membrane component is positively and / or force-fitted to the rest of the ATR sensor base assembly. However, for simplified handling of the membrane component, it is advantageous if the membrane component has a holder component to which the membrane and the sacrificial component are attached.

[0071] Such a holder component can have one or more connection forms by means of which the holder component can be connected to and fixed to the ATR sensor base assembly. The ATR sensor base assembly, in particular its sensor housing, preferably has at least one corresponding connection form. 68581 P WO Hamilton Bonaduz AG

[0072] - 15 -

[0073] Preferably, the holder component, whether it is a holder component of the ATR sensor base assembly or a holder component of the membrane component, is elastically deformable as intended, so that, through elastic deformation of the holder component during the arrangement of the membrane component on the ATR sensor base assembly, force is exerted from the holder component onto the membrane component, which pushes the membrane towards the sensor surface and which in particular leads to the displacement of sacrificial material from the area between the membrane and the sensor surface when the sacrificial component melts or softens.

[0074] Preferably, the holder component is detachably lockable to the ATR sensor base assembly, so that after the measurement process the locking engagement between the holder component and the ATR sensor base assembly can be easily released and the used membrane can be removed from the ATR sensor base assembly and replaced with a new membrane.

[0075] The present invention also relates to an ATR sensor with an ATR sensor base assembly, wherein the ATR sensor base assembly comprises a sensor housing, the sensor housing containing at least the following sensor components: a measurement radiation source for emitting measurement radiation, an ATR element, wherein the ATR element is configured as an ATR measuring element to transmit the emitted measurement radiation by reflection at at least one interface of the ATR measuring element, a measurement sensor responding to the measurement radiation, which is arranged in the sensor housing such that it detects measurement radiation emitted by the measurement radiation source after its transmission through the ATR measuring element, and which is configured to output a measurement detection signal depending on the measurement radiation detected by the measurement sensor, wherein the ATR sensor comprises a membrane component as described and further developed above. 68581 P WO Hamilton Bonaduz AG

[0076] - 16 -

[0077] The technical features of the ATR sensor described for the membrane component are further developments of the aforementioned ATR sensor. The measuring radiation is preferably infrared or near-infrared radiation.

[0078] As explained above, the ATR measuring element has a sensor area designed to generate an evanescent field. The membrane component is preferably mounted on the ATR sensor base assembly such that, in the ATR sensor's ready-to-use state, the membrane is positioned at a distance from the sensor area, forming a gap between the membrane and the sensor area. This gap is filled with the sacrificial material to at least 90% volume, preferably completely. This avoids the previously described detrimental air or gas inclusions between the membrane and the sensor area.

[0079] Preferably, the membrane component is detachably attached to the ATR sensor base assembly. The ATR sensor base assembly is advantageously reusable after a measurement. However, for hygienic reasons, a new membrane is preferably used for each measurement.

[0080] In a state prior to the attachment of the membrane component to provide a ready-to-use ATR sensor, preferably at least one of the following dimensional relationships applies in order to ensure the desired, most extensive possible filling of the gap space with sacrificial material in the ready-to-use state of the ATR sensor: i. the thickness of the sacrificial component prior to the attachment of the membrane component to the ATR sensor base assembly is greater than the thickness of the gap space in the ready-to-use state, ii. the volume of the sacrificial component prior to the attachment of the membrane component to the ATR sensor base assembly is greater than the volume of the gap space in the ready-to-use state.

[0081] The present application also relates to a method for arranging a membrane component, as described and further developed above, on an ATR- 68581 P WO Hamilton Bonaduz AG

[0082] - 17 -

[0083] Sensor base assembly for forming a ready-to-use ATR sensor, as described and further developed above, wherein the method comprises the following steps:

[0084] Arranging the membrane component on an ATR sensor base assembly in the area of ​​the sensor surface of the ATR measuring element, wherein the sacrificial component is arranged between the membrane and the sensor surface, melting or softening the sacrificial material of the sacrificial component, bringing the membrane closer to the sensor surface.

[0085] The disclosed procedures and steps for describing the membrane component and the ATR sensor are further developments of the aforementioned arrangement method. Preferably, the sacrificial component, in particular a surface of the sacrificial component facing away from the membrane, is brought into contact with the sensor surface when the membrane component is arranged on the ATR sensor base assembly.

[0086] As explained above, the sacrificial material is preferably arranged on the ATR sensor base assembly in excess volume relative to the gap it is to fill, in order to ensure that the gap is filled as completely as possible with sacrificial material. The step of bringing the membrane closer to the sensor surface therefore preferably involves displacing molten or softened sacrificial material from the gap between the membrane and the sensor surface. The force required to displace excess sacrificial material is preferably exerted by elastic deformation of a holder component that keeps the membrane ready for use on the ATR sensor base assembly, and / or by a magnetic force acting between the holder component and the ATR sensor base assembly, and / or by an external force device, such as a spring.

[0087] Melting or softening is usually a thermal melting or softening process. Since ATR sensors are generally thermally sterilized before use, melting or softening of the sacrificial material is preferably achieved during a sterilization process of the ATR sensor. The sterilization process for the 68581 P WO Hamilton Bonaduz AG

[0088] - 18 -

[0089] The thermal energy used by the ATR sensor is therefore also used to melt or soften the sacrificial component and its sacrificial material.

[0090] During sterilization, the ATR sensor base assembly and the membrane component are heated and / or exposed to a fluid sterilization medium heated relative to a room temperature of, for example, 20 °C.

[0091] When using a heated fluid sterilization medium, especially steam, which is also expelled through a nozzle and flows past the components to be sterilized, in addition to the thermal energy of the sterilization medium for melting or softening, its kinetic energy can also be used to remove molten or softened displaced sacrificial material.

[0092] The present invention will be explained in more detail below with reference to the accompanying drawings. It illustrates:

[0093] Fig. 1 shows a schematic longitudinal section view through an ATR sensor assembly of an ATR sensor of the present application,

[0094] Fig. 2 shows a schematic perspective view of an ATR sensor of the present application with a membrane component of the present application and with an ATR sensor assembly of Fig. 1 ,

[0095] Fig. 3 shows a schematic longitudinal sectional view of the ATR sensor from Fig. 2 at the beginning of a method for making the ATR sensor ready for use.

[0096] Fig. 4 shows a schematic longitudinal section view of the ATR sensor from Fig. 3 after the membrane component has been brought close to the ATR measuring element for the sacrificial component to be attached to the sensor surface of the ATR measuring element, 68581 P WO Hamilton Bonaduz AG

[0097] - 19 -

[0098] Fig. 5 shows the schematic longitudinal section view of the ATR sensor from Fig. 4 after further approximation of the membrane component to the ATR measuring element by displacement of sacrificial material and simultaneous sterilization of the ATR sensor by steam, and

[0099] Fig. 6 shows the schematic longitudinal section view of the ATR sensor from Fig. 5 after the membrane component has been arranged in its ready-to-use position.

[0100] The illustrations are not to scale.

[0101] Figure 1 shows an embodiment of an ATR sensor base assembly, generally designated by 10. The ATR sensor base assembly 10 comprises a sensor housing 12 with a tube 13, which is preferably formed in one piece. The sensor housing 12, and in particular its tube 13, can generally be made of plastic, but is preferably made of stainless steel to withstand aggressive chemical environments over the long term.

[0102] In the illustrated example, the sensor housing 12 is designed as a cylindrical housing with a cylindrical envelope 14. The cylindrical envelope 14 is indicated by a dashed-dotted line in the area of ​​a recess 16 forming a detection section of the otherwise cylindrical sensor housing 12. The sensor housing 12 extends along a longitudinal axis L, which, as the longitudinal axis L passing centrally through the sensor housing 12, is also the cylinder axis Z of the cylindrical sensor housing 12. Outside the recess 16, the cylindrical envelope 14 coincides with the outer surface 13a of the cylindrical tube 13.

[0103] In the sensor housing 12, a circuit board 18 carries an infrared radiation source 20, which in the present embodiment serves as both a measuring radiation source 22 and a reference radiation source 23. A space within the axial extent of an ATR measuring element 24 is used to accommodate the circuit board 18. A flat outer surface 24a, serving as a sensor surface 26, is designed for a measuring 68581 P WO Hamilton Bonaduz AG

[0104] - 20 - fluid to be technically detected in the external environment U of the sensor housing 12 accessible.

[0105] The infrared radiation source 20 is soldered or welded onto the printed circuit board 18 as a surface-mount device (SMD). The printed circuit board 18 is a printed circuit board 18 printed with conductive traces in a manner known per se. It also carries a control device 27, which controls the operation of the infrared radiation source 20. The printed circuit board 18, and thus the electronic components soldered, welded, or otherwise connected to it—the infrared radiation source 20 and the control device 27—can be connected by a ribbon cable 28 to a power source and / or to a higher-level control device of laboratory equipment, within which the ATR sensor base assembly 10 is used as a component of an ATR sensor 11 (see Fig. 2).

[0106] The ATR sensor base assembly 10 has a connection end 10a and a head end 10b axially opposite to the longitudinal axis L of the sensor housing. The ribbon cable 28 and a connection assembly 30 can be electrically connected to the connection end 10a. The connection assembly 30 serves to output measurement signals from a measuring sensor 32 and a reference sensor 34. At the head end 10b, the tube 13 is closed by a plug 35.

[0107] The measuring sensor 32 and the reference sensor 34 are preferably essentially identical sensor devices, which may differ, but need not differ, only in the measuring radiation band filters 36 and 38 arranged therein. For the sake of simplicity, the output of reference acquisition signals by the reference sensor 34, or their derivation from the sensor housing 12, is not shown in Figure 1, but it does occur.

[0108] In the illustrated example, both the measuring sensor 32 and the reference sensor 34 each have four detectors 40 and 42, respectively, in front of which a measuring radiation bandpass filter 36 and 38, respectively, is arranged in the beam path coming from the infrared radiation source 22. 68581 P WO Hamilton Bonaduz AG

[0109] - 21 -

[0110] The measuring sensor 32 has a total of four detectors 40, of which only the two detectors 40 located behind the longitudinal section plane containing the longitudinal axis L of the sensor housing are visible in Figure 1. The other two detectors 40 are located orthogonally to the plane of Figure 1, in front of it and in front of the two detectors 40 shown. The same applies to the measurement radiation bandpass filters 36, which are arranged in front of the incidence side of the detectors 40 in order to allow only measurement radiation with a wavelength defined by the respective measurement radiation bandpass filter 36 to fall on a detector 40.

[0111] The measurement radiation bandpass filters 36 preferably each have different wavelengths or wavelength ranges in which they are exclusively transparent to measurement radiation. Without limiting themselves to the given example, the individual measurement radiation bandpass filters 36 can transmit the following bandwidths of infrared radiation as the measurement radiation used in the exemplary embodiment, specified by their respective central wavelengths and their tolerances: 9.852 pm ± 0.024 pm, 9.569 pm ± 0.023 pm, 9.756 pm ± 0.024 pm, and 8.032 pm ± 0.016 pm. The measurement sensor 32 is thus a four-channel measurement sensor. For the example presented here, the description given for the measurement sensor 32 can also be used to explain the reference sensor 34.

[0112] The measuring sensor 32 has a housing 44 which is cylindrical over at least 75% of its extent along the longitudinal axis L of the sensor housing, with a cylinder axis Z32 that is preferably coaxial with the longitudinal axis L of the sensor housing. The same applies mutatis mutandis to the housing 46 of the reference sensor 34 and its cylinder axis Z34.

[0113] The sensor housing 12 has an axial measuring section 48 in which the measuring sensor 32 is accommodated. At an axial distance from the measuring section 48, the sensor housing 12 has an axial reference section 50 in which the reference section 50 of the infrared reference sensor 34 is accommodated. Between the measuring section 48 and the reference section 50 lies the detection section 49 of the ATR sensor base assembly 10 68581 P WO Hamilton Bonaduz AG

[0114] - 22 -

[0115] In the measuring section 48 and the reference section 50, the measuring sensor 32 and the reference sensor 34, respectively, are each received by means of an essentially identically designed annular positioning element 52. The positioning element 52 preferably has a groove on its radially outer surface for the passage of the ribbon cable 28. In the illustration, the groove on the positioning element 52 of the reference section 50 is empty. The ribbon cable 28 is guided through the groove of the positioning element 52 of the measuring section 48. However, a conductor (not shown in Fig. 1) for conveying measurement signals from the reference sensor 34 out of the sensor housing 12 can run through the groove of the positioning element 52 of the reference section 50, and further along its length also through the groove of the positioning element 52 of the measuring section 48.

[0116] The ring-shaped positioning elements 52 can be arranged in the tube 13 by frictional engagement and can hold the infrared sensor 32 or 34 they each hold in a frictional engagement. Alternatively, the positioning elements 52 can also be adhesively fixed to the tube 13 by means of an intermediate adhesive agent and can be adhesively connected to the respective sensor 32 or 34 they position in an analogous manner.

[0117] The circuit board 18 with the infrared radiation source 20 and the ATR measuring element 24 are arranged axially between the sensors 32 and 34, which are arranged with their detector surfaces facing each other. Additionally, a measurement radiation reflector 54 is arranged axially between the infrared radiation source 20 and the ATR measuring element 24. This reflector, by means of its reflective surface 54a, deflects a measurement radiation component 56 emitted by the infrared radiation source 20 and transmitted by the ATR measuring element 24 via reflection at its parallel interfaces 24a and 24b towards the bandpass filters 36 and the detectors 40 of the measurement sensor 32.

[0118] The circuit board 18 has a through-cut recess 58 at the location where the infrared radiation source 20 is mounted. The infrared radiation source 22 is arranged above the recess 58, so that it simultaneously serves as both a measuring radiation source and a measuring radiation source. 68581 P WO Hamilton Bonaduz AG

[0119] - 23 - can emit a reference radiation component 60 in the direction of the inclined surface of the ATR measuring element 24 as well as in the opposite direction.

[0120] The reference radiation component 60 reaches the reference sensor 34 via a reference radiation reflector 62, whose reflective surface 62a deflects the reference radiation component 60 towards the band filters 38 and the detectors 42.

[0121] The circuit board 18 is held by a support component 64, which is located behind the section plane of Figure 1. Another support component 64 can be located parallel to the support component 64 shown, in front of the section plane of Figure 1.

[0122] The ATR measuring element 24, which is transparent to the measuring radiation, is connected to the tube 13 by soldering via a circumferential solder section 66.

[0123] A frame 70 covers the solder gap 66. A seal 72 between the frame 70 and the solder gap 66 prevents fluid from the external environment U from entering the interior A of the ATR sensor base assembly 10 or the sensor housing 12. A recess 71, extending completely through the frame 70 in its thickness direction, provides access to a disproportionately large area E, in which an evanescent field develops during measurement operation. The frame 70 is firmly connected to the sensor housing 12 via a circumferential gap 73 filled with solder or adhesive.

[0124] Axially on both sides of the recess 71, a magnet 74 exposed to the external environment U is arranged in the frame 70 for interaction with a holder component 80 (see Fig. 2).

[0125] A smaller upper recess 76 and a deeper and wider lower recess 78 are formed at each of the two axial longitudinal ends of the recess 16 in the sensor housing 16 to detachably secure the retaining component 80 to the sensor housing 12. 68581 P WO Hamilton Bonaduz AG

[0126] - 24 -

[0127] The above-described construction method with components arranged successively in the axial direction, wherein in the axial extension area of ​​the ATR measuring element 24 the ATR measuring element 24, the infrared radiation source 20 and a large part of the circuit board 18 overlap axially, allows for a very slim dimensioning of the ATR sensor base assembly 10 and an ATR sensor 11 formed therewith, which in its cylindrical sections 48 and 50 has a dimension D orthogonal to the longitudinal axis L of the sensor housing, which does not exceed 12 mm.

[0128] In Fig. 2, the ATR sensor base assembly 10 from Fig. 1 is shown in perspective together with a membrane component 79, which is to be arranged in the recess 16 of the sensor housing 12 to form a ready-to-use ATR sensor 11.

[0129] The membrane component 79 comprises a frame-like holder component 80 with a window 82 that completely passes through the holder component 80 and is arranged in the ready-to-use ATR sensor 11 above the recess 71 of the frame 70.

[0130] The membrane component 79 further comprises a porous membrane 84 made of polytetrafluoroethylene as the membrane material 83. The pores of the membrane 84, symbolically designated only in Figures 3 and 6 by reference numeral "85", have an average pore size of approximately 0.5 pm to 1 pm. The membrane 84 is firmly connected to the flat underside of the holder component 80, which, in Figure 2, faces the recess 16 in the sensor housing 12. The outer surface 80a of the holder component 80, facing the viewer of Figure 2, is partially cylindrical, so that the membrane component 79, when ready for use on the ATR sensor base assembly 10, completes the sensor housing 12 in the area of ​​the recess 16, forming a cylinder with a uniform cylindrical outer surface.

[0131] On the side of the membrane 84 facing away from the holder component 80 and facing the recess 16 in the preparation position of the components of the ATR sensor 11 shown in Fig. 2, a sacrificial component 86 made of polyethylene glycol with a molecular weight of, for example, 4000 g / mol is placed as a sacrificial material 87 68581 P WO Hamilton Bonaduz AG

[0132] - 25 - injection molded. The reference numeral "87" is used only in Figures 3, 5 and 6 for clarity.

[0133] The holder component 80 does not need to be permanently connected to the membrane 84, however, a firm connection of the membrane 84 to the holder component 80 greatly facilitates the arrangement of the membrane component 79 on the sensor housing 12.

[0134] At both axial longitudinal ends of the holder component 80, semi-cylindrical projections 88 extending in the thickness direction of the holder component 80 are formed, which are complementary to the upper recesses 76 on the sensor housing 12 and fit into them. The semi-cylindrical projections 88 thus serve to correctly position the holder component 80 and consequently the membrane component 79 on the ATR sensor base assembly 10. Furthermore, the semi-cylindrical projections 88, in conjunction with the upper recesses 76, can serve as movement guides when the membrane component 79 approaches the ATR sensor base assembly 10 in general and the ATR measuring element 24 in particular.

[0135] Axially with respect to the longitudinal axis L of the sensor housing, locking lugs 90 protrude from the semi-cylindrical projections 88, which, in the ready-to-use state of the ATR sensor 11, comprising the ATR sensor base assembly 10 and the membrane component 79, engage in the lower recess 78 of the sensor housing 12 and thus engage the upper recess 76 in a form-fitting manner.

[0136] The holder component 80 is injection-molded from plastic and, in the illustrated embodiment, comprises permanently magnets 92 injected into it. These magnets completely penetrate the holder component 80 in the thickness direction and thus extend to the membrane 84. The polarization direction of the permanent magnets 92 corresponds to the thickness direction of the holder component 80. They are arranged to form an attractive force towards the permanent magnets 74. The permanent magnets 74 of the ATR sensor base assembly are also polarized in the thickness direction of the frame 70. In the ready-to-use state, oppositely polarized magnets are present. 68581 P WO Hamilton Bonaduz AG

[0137] - 26 - see poles of permanent magnets 92 on one side and permanent magnets 74 on the other.

[0138] The generation of a magnetic attraction between the magnetic component 79 and the ATR sensor base assembly 10 is just one example of a physical principle that can be used to achieve an attraction. In addition to or as an alternative to a magnetic attraction, the magnetic component 79 and the ATR sensor base assembly 10 can be mechanically clamped towards each other by at least one spring and / or clamp to generate a force that causes the magnetic component 79 and the ATR sensor base assembly 10 to move closer together. This force can be generated by at least one external clamp that engages the outer surface 80a of the holder component 80 on the one hand and the underside of the outer surface 13a of the tube 13 of the sensor housing 12, facing away from the recess 16, on the other hand.

[0139] Alternatively or additionally, the locking lugs 90 can project axially from the rest of the holder component 80 to such an extent that they can engage as leaf springs in corresponding receptacles on the sensor housing 13 and, due to their material and component elasticity, clamp the holder component 80 and thus the entire membrane component 79 into the recess 16 towards the ATR measuring element 24.

[0140] Figure 3 shows a longitudinal section of the ATR sensor 11 and its components: ATR sensor base assembly 10 and membrane component 79, including the longitudinal axis L of the sensor housing. The section plane penetrates the membrane component 79 in the thickness direction and divides it into two equal sections, which are mirror images of each other with respect to the section plane. The view in Figure 3 corresponds to a simplified and enlarged representation of Figure 1, with the recess 16, the mounting point for the ready-to-use membrane component 79, at the center of the illustration. Sensors 32 and 34, already explained in connection with Figure 1, are not shown in Figure 3 for the sake of simplicity.

[0141] As can be seen in Fig. 3, the sacrificial component 86 comprises a central thicker section 94 and a thinner section surrounding the thicker section 94. 68581 P WO Hamilton Bonaduz AG

[0142] - 27 -

[0143] 96. The thicker section 94 is intended to be inserted into the recess 71 of the frame 70 towards the sensor surface 26 when the membrane component 79 approaches the ATR sensor base assembly 10.

[0144] The thicker section 94 need not be strictly complementary to the recess 71, but merely needs to fit into it. Preferably, the thicker section 94, with its thickness T, already comprises a larger volume of sacrificial material 87 than the gap space 98 surrounded by the frame 70 in the recess 71. The thickness T of the thicker section 94, which thus represents the thickness of the sacrificial component 86 within the meaning of the present application, is greater than the thickness t of the gap space 98, which extends from the sensor surface 26 to the exposed upper surface 70a of the frame 70. The thickness T can be at least 1.2 times, at least 1.5 times, or at least twice the thickness or depth t of the gap space 98 to ensure that, at the end of the approach of the membrane component 79 to the ATR sensor base assembly 10, when the ATR sensor 11 is ready for use, the gap space 98 is completely filled with sacrificial material 87.In the exemplary embodiment, the depth t of the gap space 98 is between 0.35 mm and 0.40 mm, approximately 0.37 mm. In a different exemplary embodiment, the depth t of the gap space 98 can be 0.60 mm.

[0145] The thinner section 84 is provided to prevent air inclusions in the area between the membrane 84 and the frame 70 or the sensor housing 12 surrounding the frame 70, which could then enter the gap 98.

[0146] The membrane 84 was immersed in liquid sacrificial material 87 and impregnated with it before the sacrificial component 86 was injected, so that the pore volume 85a of the membrane 84 is also largely or preferably completely filled with sacrificial material 87.

[0147] In Fig. 4, the membrane component 79 is shown approximated to the ATR sensor base assembly 10 to such an extent that the thicker section 94 of the sacrificial component 86 rests on the sensor surface 26. The sacrificial component 86 thus acts as a physical barrier. 68581 P WO Hamilton Bonaduz AG

[0148] - 28 - determining for the approach of the membrane component 79 to the ATR sensor base assembly 10.

[0149] For the sake of simplicity, the locking lugs 90 are shown undeformed in Figures 4 and 5, although deformation of the locking lugs 90 is unavoidable in the relative positions shown there. However, this deformation is not relevant in the present case.

[0150] There is an air gap between the thinner section 96 and the frame 70. However, this is not mandatory. Since the primary objective of preventing air inclusions between the membrane 84 and the sensor surface 26 is to fill the gap 98 or the recess 71 with sacrificial material 87, preferably as much sacrificial material 87 as possible is arranged in the recess 71.

[0151] In the position shown in Fig. 4, the sterilization of the ATR sensor 11 can begin, whereby the thermal energy used in the sterilization process is not only used to sterilize the ATR sensor 11, but also advantageously to melt the sacrificial material 87.

[0152] Fig. 5 shows how a steam nozzle 99 emits hot steam 100 towards the ATR sensor 11. The hot steam 100 has a temperature between 120 °C and 140 °C, which gradually heats up the ATR sensor 11.

[0153] Through the window 82, the hot water vapor 100 can directly reach the membrane 84 and thus transfer heat particularly quickly to the thicker section 94 of the sacrificial component 86.

[0154] In addition to gravity, the attractive force of the magnets 74 and 92, when the sacrificial material 87 is sufficiently liquefied by melting, drives the membrane component 79 and the ATR sensor base assembly 10 towards each other, whereby molten sacrificial material 87 from the area between the membrane 84 and the surface of the sensor housing 12 facing the membrane is drawn into the recess 16 by the gravity- and magnetic force-induced approach of the 68581 P WO Hamilton Bonaduz AG

[0155] - 29 -

[0156] The membrane component 79 is displaced to the ATR sensor base assembly 10 and blown away by the steam jet from the ATR sensor 11.

[0157] It should be noted again that the illustrated embodiment is only a rough schematic representation. If the locking lugs 90 excessively impede the gravity- and magnetically induced approach of the membrane component 79 and the ATR sensor base assembly 10 to one another, for example due to frictional forces occurring between the locking lugs 90 and the vertical flanks of the sensor housing 12 in the recesses 76, the locking lugs 90 can be omitted, or the magnets 92 and 74 can be omitted and the locking lugs 90 can be supported as spring elements projecting from one side of the holder component 90 on spring abutments of the ATR sensor base assembly 10, in particular of the sensor housing 12, and clamp the membrane component 79 towards the ATR sensor base assembly 10 and in particular towards the ATR measuring element 24 due to its material and component elasticity.

[0158] In Fig. 6, the entire sacrificial material 87 has liquefied during sterilization, and the membrane component 79 is completely brought into close proximity with the ATR sensor base assembly 10. The membrane 84 rests against the frame 70 without any gaps. A thin film of sacrificial material 87 may still be present between the membrane 84 and the frame 70.

[0159] The locking lugs 90 engage behind the material of the sensor housing 12 at the end of the recess 76 closer to the sensor surface 26 and thus anchor the holder component 80 to the membrane 84 in the recess 16.

[0160] The gap 98 is completely filled with sacrificial material 87. The originally present sacrificial component 86 no longer exists in its original form.

[0161] The supply of hot steam 100 can be stopped after sufficient sterilization. The sacrificial material 87 polyethylene glycol, which is water-soluble in the present embodiment, can then, when the ready-to-use ATR sensor 11 of Fig. 6 is arranged in an environment U of aqueous target liquid ZF, be drawn through the pores 85 of the membrane 84 by the aqueous target liquid ZF in the gap space 98 68581 P WO Hamilton Bonaduz AG

[0162] - 30 - reached, dissolved, and diffusion-driven through the pores 85 of the membrane 84 into the environment U, where the biologically inert sacrificial material 87 is diluted to negligible levels. The target liquid ZF is represented by a point cloud in Fig. 6.

[0163] In the aforementioned embodiments of the membrane 84, with a thickness m (see Fig. 3) in the range of 30 pm to 70 pm, after about 1 hour the gap space 98 is sufficiently freed of sacrificial material 87 that the target liquid of the desired measurement process can be measured with sufficient accuracy in the evanescent field of the totally reflected measurement radiation in the ATR measuring element 24 outside the sensor area 26.

[0164] Undesirable gas bubbles between the membrane 84 and the sensor surface 26, which could distort the measurement result, can thus be reliably avoided without compromising sterilization. After completion of the measurement process, the ATR sensor base assembly 10 can be reused after appropriate cleaning. For this purpose, the used membrane component 79 is discarded and replaced by a new membrane component 79, which is arranged on the ATR sensor base assembly 10 according to the procedure described above.

Claims

1. 68581 P WO Hamilton Bonaduz AG - 31 - Claims 1. Membrane component (79) for arranging a membrane on an ATR measuring element (24) conducting a measuring radiation at a distance from a sensor surface (26) of the ATR measuring element (24) intended to form an evanescent field, wherein the membrane component (79) comprises: a membrane (84) permeable to a target fluid (ZF) made of a membrane material (83) and a sacrificial component (86) arranged on one side of the membrane (84), which is formed from a sacrificial material (87) different from the membrane material (83) and which is soluble in the target fluid (ZF).

2. Membrane component (79) according to claim 1, characterized in that the sacrificial material (87) has at least one of the following thermal stability properties: a melting temperature or a softening temperature which is higher than 23 °C, a melting temperature or a softening temperature of the sacrificial material (87), a lower than 120 °C, or a non-boiling temperature at least at temperatures below 140 °C.

3. Membrane component (79) according to claim 1 or 2, characterized in that the sacrificial material (87) comprises polyalkylene glycol and / or polyethylene glycol and / or polypropylene glycol and / or a polyethylene-polypropylene glycol copolymer.

4. Membrane component (79) according to claim 3, characterized in that the sacrificial material (87) is polyethylene glycol with a molar mass in the range of 3500 g / mol to 6500 g / mol 68581 P WO Hamilton Bonaduz AG - 32 - 5. Membrane component (79) according to one of the preceding claims, characterized in that the sacrificial component (86) has a greater thickness (T) in a common thickness direction of membrane (84) and sacrificial component (86) than the membrane (84).

6. Membrane component (79) according to one of the preceding claims, characterized in that the membrane (84) has a thickness (m) in the range of 30 pm to 300 pm.

7. Membrane component (79) according to one of the preceding claims, characterized in that the sacrificial component (86) has a thickness (T) in the range of 300 to 1000 pm.

8. Membrane component (79) according to one of the preceding claims, characterized in that the membrane (84) has pores (85) which provide a pore volume (85a) in the membrane (84), wherein the pore volume (85a) is at least partially filled with sacrificial material (87).

9. Membrane component (79) according to one of the preceding claims, characterized in that it has a holder component (80) on which the membrane (84) is held with the sacrificial component (86).

10. ATR sensor (11) with an ATR sensor base assembly (10), wherein the ATR sensor base assembly (10) comprises a sensor housing (12), wherein the sensor housing (12) contains at least the following sensor components: a measurement radiation source (22) for emitting a measurement radiation (56), an ATR element (24), wherein the ATR element (24) is configured as an ATR measurement element (24) to transmit the emitted measurement radiation (56) by reflection at at least one interface (24a) of the ATR measurement element (24), a measurement sensor (32) responding to the measurement radiation (56), which is arranged in the sensor housing (12) such that it is protected from the measurement radiation (56). 68581 P WO Hamilton Bonaduz AG - 33 - The radiation source (22) emits measurement radiation (56) after its transmission through the ATR measuring element (24), and which is configured to output a measurement detection signal depending on the measurement radiation (56) detected by the measuring sensor (32), wherein the ATR sensor (11) has a membrane component (79) according to one of the preceding claims.

11. ATR sensor with membrane component (79) according to claim 10, characterized in that the ATR measuring element (24) has a sensor surface (26) designed to form an evanescent field (E), wherein the membrane component (79) is received on the ATR sensor base assembly (10) such that the membrane (84) is arranged in the ready-to-use state of the ATR sensor (11) forming a gap (98) between the membrane (84) and the sensor surface (26) at a distance from the sensor surface (26), wherein the gap (98) is filled to at least 90% by volume with the sacrificial material (87).

12. ATR sensor with membrane component (79) according to claim 10 or 11, characterized in that the membrane component (79) can be detachably attached to the ATR sensor base assembly (10), wherein at least one of the following dimensional relationships applies before the membrane (84) is attached in the ready-to-use state: i. the thickness (T) of the sacrificial component (86) before the membrane component (79) is attached to the ATR sensor base assembly (10) is greater than a thickness (t) of the gap space (98) in the ready-to-use state, ii. the volume of the sacrificial component (86) before the membrane component (79) is attached to the ATR sensor base assembly (10) is greater than a volume of the gap space (98) in the ready-to-use state.

13. Method for arranging a membrane component (79) according to one of claims 1 to 9 on an ATR sensor base assembly (10) to form a ready-to-use ATR sensor (11) according to one of claims 10 to 12, wherein the method comprises the following steps: 68581 P WO Hamilton Bonaduz AG - 34 - Arranging the membrane component (79) on the ATR sensor base assembly (10), in particular on the sensor surface (79), of the ATR measuring element (24), wherein the sacrificial component (86) is arranged between the membrane (84) and the sensor surface (26), Softening the sacrificial material (87) of the sacrificial component (86), bringing the membrane (84) closer to the sensor surface (26).

14. Method according to claim 13, characterized in that the step of bringing the membrane (84) closer to the sensor surface (26) is carried out by displacing softened sacrificial material (87) from the gap space (98) between the membrane (84) and the sensor surface (26).

15. Method according to claim 13 or 14, characterized in that the softening is a thermal softening which is effected during a sterilization process of the ATR sensor (11 ) during which the ATR sensor base assembly (10) and the membrane component (79) are heated and / or exposed to a fluid sterilization medium (100) heated relative to room temperature.

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