Membrane, membrane contactor, and method for producing a membrane

Abstract

The invention relates to a membrane (1) for a membrane contactor (2), which membrane is in the form of a hollow three-dimensional tube structure located on both sides of a plane / central plane (ME), in particular a hollow tube structure which is mirror-symmetrical to the plane / central plane and consists of branched tubes (3, 3´, 3´´, 3´´´, 3´´´´), preferably not exclusively planar branched tubes (3, 3´, 3´´, 3´´´, 3´´´´) having a plurality of branching planes (VE) in parallel with the plane / central plane (ME) on both sides of the plane / central plane (ME), wherein the walls of the tube structure are permeable to substances and / or permeable to energy, and wherein, in the region (B) of each branching plane (VE), each tube (3, 3´, 3´´, 3´´´) extending towards the plane / central plane (ME) branches into a plurality of tubes (3´, 3´´, 3´´´, 3´´´´) extending with respect to the plane / central plane (ME), and the tubes (3´´´´) extending from both sides of the plane / central plane (ME) from the corresponding last branching plane (VE) with respect to the plane / central plane (ME) merge into one another in the region (ÜB) of the plane / central plane (ME). The invention also relates to a membrane contactor (2) having a membrane of this type, and to a method for producing a hollow membrane (1).

Description

[0001] July 23, 2025

[0002] RWTH Aachen

[0003] Membrane, membrane contactor and method for manufacturing a membrane

[0004] The invention relates to a membrane and a membrane contactor with such a membrane. The invention also relates to a method for manufacturing a membrane of a membrane contactor.

[0005] Membrane contactors are known in the prior art and, as in the invention, serve to indirectly contact two fluid media, which are guided on both sides of a membrane, via the membrane. They are used, for example, to carry out extraction, stripping, or absorption processes between the media, which are guided past each other as fluids separated by the membrane.

[0006] Energy can be transferred across the membrane between the media, for example to regulate the temperature of one medium using the other. In such a case, the membrane is at least energy-permeable.

[0007] Many applications, particularly those related to the invention, aim to transfer at least one substance from one medium across the membrane into the other. Substance exchange across the membrane often occurs in both directions. A typical application, which is also preferred for the invention, is the use of the membrane contactor and the membrane it contains as an oxygenator. In this application, oxygen is transferred from a gaseous fluid, particularly oxygen gas or an oxygen-containing gas, across the membrane into blood, and conversely, carbon dioxide is transferred from the blood across the membrane into the gas. This allows the blood to be enriched with oxygen and depleted of carbon dioxide. Another application, which also uses blood as one of the media, is dialysis and the removal of carbon monoxide from blood.In such applications of the invention, in which at least one substance is transferred between the media across the membrane, the membrane according to the invention is designed to be permeable to substances, in particular it is designed to be semipermeable.

[0008] A substance-permeable membrane is therefore preferably understood to be a so-called semipermeable membrane, which forms a partition that is permeable only to certain substances in a medium on one side of the membrane, allowing these substances to pass through the membrane into a medium on the other side. This transfer occurs, for example, by diffusion. Substances other than the specified ones cannot pass through the membrane. The membrane, or partition, is thus selectively permeable.

[0009] This is the case, for example, with the aforementioned blood oxygenators, where the membrane is permeable to oxygen and carbon dioxide, but not to other components of the blood, especially not to blood plasma.

[0010] A material-permeable, preferably semi-permeable membrane according to the invention is therefore preferably only permeable to gaseous components of the media on both sides of the membrane, but not to solid or liquid components of the media, in particular wherein one of the media is blood.

[0011] Hollow fibers are frequently used in membrane contactors, with one medium passing through the hollow fibers and another flowing around the outside of the hollow fibers. This is commonly the case, for example, with blood oxygenators.

[0012] A particular problem in the application of blood oxygenators is that a large foreign body surface area comes into contact with the blood, and that the blood flow through and around the hollow fibers is not physiologically optimal. For example, areas of stagnation can occur in the flow, which can contribute to thrombus formation.

[0013] Against this background, an object of the invention is to replicate physiological flow conditions in a membrane contactor or with a membrane for such a membrane contactor and to provide a method for manufacturing a corresponding membrane. Regardless of a preferred application as an oxygenator, the invention should generally provide the possibility of distributing the media involved in the exchange as evenly as possible and guiding them past each other, e.g., in countercurrent flow.This problem is solved – particularly across applications – by a membrane for a membrane contactor that, according to the invention, is characterized by being designed as a hollow, mirror-symmetrical tubular structure with respect to a central plane, consisting of branched tubes with several branching planes parallel to the central plane on both sides of the central plane, wherein the walls of the tubular structure are material-permeable and / or energy-permeable, and wherein, in the region of each branching plane, each tube extending towards the central plane branches into several tubes extending towards the central plane, and the tubes extending from the last branching plane on both sides of the central plane merge into one another in the region of the central plane. Preferably, a material-permeable membrane of the invention is semipermeable according to the preceding definition.

[0014] This results in the membrane forming a hollow, three-dimensional tubular structure, in particular a hollow capillary structure, which, in the preferred application as a membrane contactor for blood, resembles the structure of blood vessels that branch out increasingly from large blood vessels towards smaller blood vessels and conversely also merge again to form larger blood vessels. Due to the mirror symmetry formed according to the invention about a central plane, such a tubular structure is easier to describe technically and thus also easier to manufacture.

[0015] Preferably, the tube structure is formed from tubes that are not exclusively planar branched, in particular meaning that the tubes resulting from a tube after branching do not all lie in the same plane or in parallel planes with the tube before branching.

[0016] This achieves the effect that, when a medium flows through the tube structure towards the central plane, it is initially divided into progressively smaller flows, and after passing through the central plane, these smaller flows gradually merge. Advantageously, the same applies to the medium flowing around the outside of the membrane, because the tube structure similarly divides the flow into smaller flows and then, after passing through the central plane, merges these smaller flows.

[0017] Particularly when used with blood, this results in physiological flow conditions, which are considered less damaging to the blood compared to conventional hollow-fiber designs. The multi-branched tubular structure offers the advantage of a more compact design across all applications, not just blood applications, leading to higher transfer efficiency relative to pressure loss and surface area.

[0018] With such a membrane designed according to the invention, a membrane contactor can be formed according to the invention, comprising a housing with an exchange chamber, wherein at least one such hollow material-permeable and / or energy-permeable membrane according to the invention is arranged in the exchange chamber, with which the exchange chamber is divided into two chamber areas, wherein a first chamber area borders the membrane surface of the hollow membrane on the inside and a second chamber area borders the membrane surface of the hollow membrane on the outside, wherein openings are provided on the housing through which a first exchange medium can be guided through the first chamber area, in particular through the interior of the hollow membrane, and openings are provided through which a second exchange medium can be guided through the second chamber area, in particular along the outside of the membrane.

[0019] Insofar as preferred embodiments of the membrane according to the invention are described below, these apply in the same way to the membrane contactor according to the invention, since it comprises at least one membrane according to the invention, preferably exactly one membrane according to the invention.

[0020] A preferred embodiment of the membrane provides that, starting from a single tube on each side of the central plane, the number of tubes increases towards the central plane.

[0021] This preferably achieves the result that one of the individual tubes on both sides of the central plane forms a connection for the inflow of a medium into the tube structure, and the other forms a connection for the outflow of this medium from the tube structure. The inflow and outflow are thus located opposite each other around the central plane.

[0022] In a membrane contactor formed with such a membrane, each of the two individual tubes can be designed so that it passes through a housing wall, terminates in the housing wall, or is connected to an adapter element through which the medium is connected. The open end of such a tube can thus serve directly as an opening in the housing to introduce and discharge the medium, which flows inside through the hollow membrane. An end section of each individual tube can also serve directly as a pipe connection to which the medium can be connected.

[0023] According to the invention, the tubes branch in the region of a respective branching plane, in particular in a region on both sides of the branching plane, or in a region in which the branching plane lies. This region of a branching plane extends in the direction towards the central plane, in particular perpendicular to the central plane. In particular, it is defined as a region extending from a point, in particular viewed in the direction towards the central plane, upstream of the branching plane, where a single closed cross-section of a tube is present, extending into the region and branching therein, to a point downstream of the branching plane where a number of n individual, in particular non-overlapping, individual cross-sections of n tubes are present, extending out of the region in the direction towards the central plane, where n is the number of branches.In particular, the branching plane is located at least substantially in the center of the area where the branching of a tube occurs. The number n of branches is preferably greater than or equal to 3, more preferably greater than or equal to 4, more preferably greater than or equal to 5, and more preferably greater than or equal to 6.

[0024] A structurally advantageous embodiment provides that, within the same branching plane, each tube extending into that plane branches into the same number of tubes extending out of that plane. However, the number of branches can differ in areas of different branching planes. The extension of the tubes is preferably always considered here and elsewhere in the description of the invention in the direction of the central plane.

[0025] In particular, it is provided that there are at least two branching levels on each side of the central plane, preferably at least three branching levels, as well as the corresponding regions. A branch can be understood as the part of the tube structure that is arranged within a respective region of a branching level.

[0026] A further preferred embodiment provides that within each branching level, every tube extending into that level branches into the same number of tubes extending out of that level. This results in the number of branches being the same throughout the tube structure. More generally, it is preferable that all tubes resulting from a branching point are arranged at an angular distance from one another around a central axis that penetrates the tube before the branching point; preferably, all tubes resulting from a branching point are arranged at the same angular distance from one another around a central axis that penetrates the tube before the branching point. Preferably, the cross-section of none of these tubes after the branching point is penetrated by the central axis of the tube before the branching point.In particular, the centers of all cross-sections of tubes resulting from a branching thus have a radial distance to the central axis that is greater than the radius of each respective tube resulting from a branching.

[0027] In general, it can also be provided that a portion of all tubes resulting from a branch are arranged at an angular distance from each other around a central axis which penetrates the tube before the branch, preferably that a portion of all tubes resulting from a branch are arranged at the same angular distance around a central axis which penetrates the tube before the branch, and that (exactly) one tube resulting from the branch runs coaxially to that of the tube before the branch, in particular coaxially to its central axis.

[0028] This tube, coaxial with the tube before the branch, preferably has a smaller cross-section than the tube before the branch; in particular, it has the same cross-section as those tubes that form the aforementioned part of all tubes. Specifically, this part of all tubes has a number that is one less than the total number of all tubes resulting from the branch.

[0029] In particular, the centers of all cross-sections of tubes in the aforementioned part of all tubes arising from a branching point have a radial distance from the central axis that is greater than the radius of each respective tube arising from a branching point. The center point in the cross-section of such a coaxial tube preferably lies exactly on the aforementioned central axis of the tube before the branching point.

[0030] In the aforementioned embodiments, the tube prior to the branching is preferably understood to be the tube that extends into the region of a branching plane in which the branching takes place. In the aforementioned embodiments, each tube resulting from the branching is preferably understood to be a tube that extends out of the region of a branching plane in which the branching takes place. In the aforementioned embodiments, the central axis of the tube prior to the branching is preferably oriented perpendicular to the branching plane, at least in a section of its extension.

[0031] More preferably, each tube extending into the area of ​​a branching plane, and in particular each tube extending out of the area, has at least in one section an extension in the direction of the middle plane that is perpendicular to the branching plane.

[0032] Preferably, in the tube that extends into the branching plane, a central axis is present in such a section of the extension, which lies centrally / in the cross-section of the tube.

[0033] In particular, each tube extending out of the branch also has, at least in one section, a central axis that is perpendicular to the branching plane and / or that runs parallel to or is identical with the central axis of the tube before the branch, especially in the case of the aforementioned coaxial tube.

[0034] Preferably, each tube of the tube structure has such a section before and / or after a region of a branching plane in which the branching takes place, or between two regions of branching planes adjacent to each other in the direction of the central plane. In particular, such a section exists between two hierarchically distinct branching planes. It is further preferably provided that the respective central axis of at least the aforementioned part of all tubes, preferably of all tubes that arise from a branching, and in particular of those extending from the region of a branching plane in which the branching takes place, in the direction of the central plane, spans a plane with the central axis, in particular with the parallel central axis of the tube before the branching, and in particular with the central axis extending into the region of a branching plane in which the branching takes place.

[0035] Preferably, each spanned plane is oriented perpendicular to a branching plane, particularly if the central axis of the tube before the branching and the central axis of a tube after the branching are parallel.

[0036] In particular, it is provided that if there is an odd number n of branches, all such spanned planes are different from each other. In particular, it is provided that if there is an even number n of branches, at least two such spanned planes are different from each other. Preferably, different planes are also not parallel to each other.

[0037] Preferably, all tubes of the membrane are parallel to each other at least in a section of their extent and preferably perpendicular to the central plane and / or to each branching plane. Such sections of the tubes, where this applies, are preferably located before and / or after a region in which a branching occurs or between two such regions of adjacent branching planes.

[0038] The invention preferably provides that the cross-sectional area / diameter of each tube after a branching is smaller than the cross-sectional area / diameter of the tube before the branching, in particular that the cross-sectional area / diameter of the tubes decreases with each branching in the direction towards the central plane.

[0039] Preferably, the cross-sectional dimension / diameter of each tube after each branch is smaller by the same factor, at least in the region of the same branching level, and preferably in the respective regions of all branching levels, than the dimension of the tube before the branch. For example, this factor can be equal to or greater than the number of branches.

[0040] Preferably, the same factor is present at all branches of the tube structure. However, it is also possible for the factor to differ at different branching levels.

[0041] In particular, it can also be provided that the factor decreases towards the mid-plane. For example, at the first branching, especially the one following a single tube through which the medium enters or exits the membrane, the largest factor can be chosen to achieve a very strong reduction in the volume of the tube structure in the region of the branching plane, and smaller factors can then be used thereafter.

[0042] A preferred embodiment provides that the tube structure is at least partially self-similar / fractal, particularly in the region from a first branch to a final branch before the central plane. Specifically, no branches are present in a boundary region on either side of the central plane because the tubes merge there. It is therefore possible that no self-similarity exists in this region.

[0043] Self-similarity is preferably understood to mean that the same basic geometry is found at different locations within the tubular structure, differing only in size / scale. Such a basic geometry is preferably the branching, in particular, according to the preceding definition, preferably the geometric structure of the membrane within a region of a branching plane.

[0044] It is further preferred in all possible embodiments that the tubes merging into one another at the central plane cross the central plane in a direction perpendicular to the central plane and / or that all tubes crossing the central plane run parallel to each other in a region around the central plane.

[0045] In the area on both sides of the central plane, where the tubes extending from both directions towards the central plane merge into one another, the highest number of tubes is found after a branching level. In this area, a membrane contactor thus has the opportunity to achieve the largest possible exchange surface in the smallest possible space.

[0046] Preferably, the tubes merging into one another at the central plane, particularly those extending towards the central plane after the last branching level, have a cross-section that deviates from a circular shape. Preferably, the cross-section of each such tube is star-shaped, preferably with at least three arms, preferably with at least four arms, and preferably with at least five arms. Preferably, the ends of the respective arms are rounded.

[0047] This allows the effective surface area to be increased for a predetermined effective flow cross-section of a given tube compared to the surface area that would be present with a circular cross-sectional shape.

[0048] Preferably, the transition area of ​​the tubes, located on both sides of the central plane, particularly between the regions of the last branches on both sides of the central plane, preferably in which the tubes all run parallel to each other and preferably perpendicular to the central plane, extends further in a direction perpendicular to the central plane than the minimum distance between two adjacent branching planes on the same side of the central plane, and preferably also further than the maximum distance between two adjacent branching planes on the same side of the central plane. Particularly in the latter case, the transition area is the longest (perpendicular to the central plane) extended region of the tube structure, especially between two branching planes.

[0049] In terms of design, it is preferred that the tubes in the area of ​​the transition of the tubes, in particular between the areas of the last branches on both sides of the central plane, have the smallest cross-section / diameter of all tubes of the tube structure, in particular a cross-section / diameter which is in the range of 250 micrometers to 50 micrometers.

[0050] A further preferred embodiment, which can be combined with all possible embodiments, provides that at least one tube is connected from a branch within a region of a branching plane, extending out of the region towards the central plane, to another tube from an adjacent branch within the region of the same branching plane, extending out of the region towards the central plane, in particular to form a common tube.

[0051] Preferably, the membrane thickness decreases towards the central plane, and in particular, the thickness differs in the region of each branching plane. Preferably, the membrane thickness in the region of the tubes crossing the central plane is in the range of 10 micrometers to 200 micrometers.

[0052] In the design of a membrane contactor with a membrane according to the invention, it is preferably provided that the second medium, e.g., a gas, can be supplied through the wall of the housing into the second chamber region by means of a lance, wherein the open end of the lance located in the chamber region lies between the branched tubes in or after a branching point, preferably centrally between the branched tubes in or after a branching point, in particular in or after the very first branching point. Preferably, the open end of the lance can have a distributor nozzle / diffuser. More preferably, the end of the lance is open in the direction of the central plane.

[0053] Preferably, a method for producing a membrane or a hollow tube structure according to the invention comprises an additive manufacturing process, in particular a 3D printing process. Preferably, in a first possible embodiment, the membrane or the tube structure may be produced directly from the membrane material.

[0054] A second possible embodiment involves the membrane, or the tubular structure, being indirectly produced additively from the membrane material. Preferably, this means that the tubular structure is not created directly by the additive manufacturing process, but rather that an auxiliary component, in particular the manufacturing body described below, is produced by the additive manufacturing process, which is then used to further manufacture the membrane.

[0055] The 3D printing process preferably used is based, for example, on stereolithography (SLA), preferably the MSLA process.

[0056] In the second option for indirect manufacturing, it is preferably provided that a manufacturing body is first produced by an additive manufacturing process, in particular by 3D printing, which corresponds to the inner volume of the tube structure of the membrane to be produced.

[0057] It is therefore provided that the manufacturing body is coated with a coating agent which comprises the material or is formed by the material which forms the membrane, after which the deposited coating agent forms the tubular structure of the membrane which is supported by the manufacturing body.

[0058] The manufactured body is then disassembled, in particular leaving behind the tubular structure of the hollow membrane.

[0059] ZB, the process may involve coating with a liquid, hardenable coating agent, preferably a polymer. For this purpose, the workpiece can, for example, be immersed in the liquid coating agent. It is preferably provided that excess coating agent is removed, preferably by centrifuging the workpiece. Hardening preferably occurs through polymerization of the coating agent, in particular through polymerization to a hardened polymer suitable as a membrane material.

[0060] Preferably, the coating agent is a mixture of at least two components. These two components preferably comprise a solvent or a reactant and a polymer or a prepolymer. A polymer or a prepolymer can preferably be an elastomer.

[0061] Suitable polymers / prepolymers as cured or curable coating materials are preferably acrylates, polytetrafluoroethylene (PTFE), polysulfone (PSU), polyethersulfone (PES), or polymethylpentene (PMP). Suitable elastomers / elastomeric prepolymers as cured or curable coating materials are preferably silicone, polydimethylsiloxane (PDMS), or polyurethane (PU).

[0062] The coating (dip) and removal (centrifugation) process can be repeated several times, especially after intermediate curing, preferably to achieve a desired layer thickness.

[0063] Alternatively, the coating can also be applied by depositing the coating material onto the workpiece from the gas phase. Preferably, in this case, polytetrafluoroethylene (PTFE), a fluoropolymer, parylene, polyethylene, or polymethyl methacrylate (PMMA) is deposited.

[0064] One preferred further development method involves treating the workpiece before coating to render it inactive / inert against a reaction with the coating material. For example, the workpiece can be heated and / or exposed to plasma.

[0065] To dissolve the manufactured body, it is preferably provided that the coated manufactured body is immersed in or rinsed with a solvent with which the material of the manufactured body, but not the coating agent, is soluble.

[0066] Preferably, NaOH is used as the solvent, especially if the material of the manufactured body is made of polydimethylsiloxane (PDMS) or polytetrafluoroethylene (PTFE).

[0067] The invention may provide that the manufactured body is produced completely solid, completely hollow, or partially hollow and partially solid.

[0068] For example, a manufactured body can be produced that forms partly a tubular structure and partly a solid rib structure. In particular, a hollow tubular structure of the manufactured body can be additively produced up to the last or penultimate branching level. The at least partially hollow design of the manufactured body has the advantage that the hollow areas can be flushed with the solvent, leading to faster dissolution of the manufactured body.

[0069] Regardless of the specific design of the manufactured body, it is preferably provided that the outer dimension of the manufactured body, in particular in all tube and / or web areas, is smaller by a dimension corresponding to the membrane thickness than the desired tube structure of the membrane.

[0070] The membrane thickness can preferably be at least 10 micrometers, and in particular at most 200 micrometers.

[0071] The invention is described above with a mirror symmetry around a central plane. However, the invention can also provide that a membrane according to the invention for a membrane contactor is characterized in that it is designed as a hollow tube structure lying on both sides of a plane, consisting of branched tubes with several parallel branching planes on both sides of the plane, wherein the walls of the tube structure are material-permeable and / or energy-permeable, and wherein in the region of each branching plane at least one, preferably each, tube extending towards the plane branches into several tubes extending towards the plane, and the tubes extending towards the plane from both sides of the plane, in particular from the last branching plane, merge into one another in the region of the plane.All other previously described explanations / further developments also apply to this type of membrane, whereby the term "intermediate plane" is to be replaced by the term "plane," in particular one that can also be produced using the same method and with which a membrane contactor can be formed in the same way, which can otherwise exhibit all the other previously mentioned features. Thus, in the sense of the earlier description, the plane is preferably an intermediate plane around which the mirror symmetry already described at the outset preferably exists.

[0072] The invention is described in more detail using the figures.

[0073] Figures 1 and 2 show the membrane 1 of a membrane contactor 2 according to the invention, which is illustrated in Figures 6 and 7. The membrane 1 is designed as a hollow tubular structure that is mirror-symmetrical about the central plane ME. It is clearly visible here that the tubular structure extends on both sides of the central plane from a single tube 3, which extends in the direction of the central plane ME, in particular perpendicular to it, and branches multiple times, in particular six times, in several regions B of branching planes VE.

[0074] In this example, the single tube 3 thus creates six new tubes 3' in area B of the first branching level VE.

[0075] In general, it is preferable that all tubes (here the tubes 3') resulting from a branching are arranged at an angular distance from each other, preferably at the same angular distance around a central axis which passes through the tube (here the tube 3) before the branching.

[0076] Each tube 3' that arises from a branch in region B of a branching level VE then branches in the next region of a subsequent branching level VE into six new tubes 3" and so on. These branches are repeated according to the number of branching levels VE provided on one side of the central level ME. In this example, four branching levels VE are provided, so that the tubes 3"" last formed by branches extend from both sides onto the central level ME and merge into one another through the central level ME. The number of branching levels on one side of the central level is generally arbitrary for the purposes of the invention.

[0077] In this illustrated embodiment, the number of branches at each branching level VE is the same, but this is not strictly necessary for the invention. The number of branches at each branching level VE can also be different.

[0078] In the example shown here, this results in a self-similarity of the tubular structure of membrane 1, in which a basic geometry GG occurs repeatedly, identically except for differences in size. This basic geometry GG is shown in the lower left of Figure 1. Such a basic geometry GG can, for example, be a branching or a geometry consisting of a section of a tube extending into a region, the branching within the region, and several sections of tubes extending out of the region.

[0079] In the latter case, the basic geometry around the respective tube section is larger than a branch. The cross-section of the tubes preferably decreases continuously towards the central plane ME, preferably by a factor corresponding to the number of branches, or by a factor corresponding to the reciprocal of the number of branches. This factor can also vary depending on the branching level in other embodiments.

[0080] Due to the self-similarity and the number of branches of 6, the tubular structure exhibits a hexagonal cross-sectional shape in the region of the central plane ME. In general, the membranes according to the invention can have an N-sided cross-sectional shape at the central plane, where N corresponds to the number of branches (particularly at all branching levels).

[0081] Figure 1 further visualizes an optional embodiment in which a 3V" tube is connected from a branch within a region B of a branching plane VE extending out of region B towards the midplane ME to another 3V" tube from an adjacent branch within region B of the same branching plane VE extending out of region B towards the midplane ME.

[0082] In contrast, Figure 3 shows, as an example, a membrane 1 with a tubular structure having five branches, and Figure 4 shows a membrane 1 with a tubular structure having four branches. Both tubular structures are also self-similar.

[0083] Figure 5 essentially adopts the embodiment with six branches shown in Figures 1 and 2, but differs in that the transition region ÜB, in which the tubes 3"" merge into one another after a final branch and which is bisected by the central plane ME, has the longest extent of all the regions located between adjacent branch planes VE. This is advantageous because the transition region has the highest tube density and thus the largest exchange surface per unit of extent.

[0084] Figures 1 to 5 show membranes in which, according to the previous description, all tubes resulting from a branch are arranged at an angular distance from one another, preferably at equal angular distances around a central axis that penetrates the tube upstream of the branch. In contrast, Figure 6A shows an overall view and Figure 6B a detail view in the transition area at the central plane of an embodiment in which some of all tubes resulting from a branch are arranged at equal angular distances from one another around a central axis MA that penetrates the tube upstream of the branch, and in which a tube 3MA resulting from the branch runs coaxially with the tube upstream of the branch, in particular coaxially with the central axis MA, to which the tube upstream of the branch runs parallel at least in one section, and which thus lies centrally in the cross-section of the tube in such a section.

[0085] Figure 7 shows a preferred embodiment that can be combined with all possible embodiments of the invention, whether shown or not. According to this embodiment, it is preferably provided that the tubes (3") merging into one another at the plane / middle plane (ME), in particular those extending towards the plane / middle plane (ME) after the last branching plane (VE), have a cross-section that deviates from a circular shape. Preferably, the cross-section of each such tube is star-shaped, preferably star-shaped with at least three or exactly arms, preferably with at least four or exactly arms, and preferably with at least five or exactly arms. Preferably, the respective arm ends are rounded.

[0086] Figure 8A shows in a side view and Figure 8B in a top view the spatial arrangement of a tube 3 extending into the area B of a branching plane VE and all tubes 3' extending out of the area B of a branching plane VE at a single branching, in particular a branching from the membrane or tube structure of Figures 1, 2, 5 or 6A / 6B.

[0087] Tube 3 can also be referred to as the tube before the branching and tubes 3' as the tubes after the branching, especially if it is defined that the branching takes place in area B.

[0088] It is evident here that tube 3, which extends into region B, has a section of its extension, specifically the section in front of region B, in which the extension has a central axis MA that is oriented perpendicular to the branching plane VE. Each tube 3' also has a section of its extension, specifically the section after region B, in which the respective extension has a central axis MA' that is oriented perpendicular to the branching plane VE. The central axis MA and the respective central axis MA' are all parallel to each other.

[0089] Figure 8B shows the position of the tubes 3, 3' for graphical simplification without showing the transition between tube 3 and the respective tube 3', in particular at the respective location of the section with the extension according to the central axes MA and MA'.

[0090] If, optionally, as shown here with a dashed line, there is also a tube 3' that is coaxial to tube 3, its central axis MA' is identical / coaxial to the central axis MA of tube 3. For all tubes 3' that do not correspond to a coaxial tube, their central axes MA' are parallel to and spaced apart from the central axis MA, in particular where the distance is greater than the radius of the cross-sectional area of ​​each tube 3'.

[0091] Figures 8A and 8B illustrate that all tubes 3' after the branching, provided there is no coaxial tube 3', or at least some of all tubes 3' – if there is a coaxial tube 3' – are arranged at an angular distance, preferably an equal angular distance, around the central axis MA of the tube 3, which extends into region B. The centers or central axes MA' of the tubes 3' also have a radial distance from the central axis MA. Only the optional tube 3' after the branching has no radial distance, or this distance is zero.

[0092] Accordingly, such a branching pattern results in a three-dimensional tube structure in which the branches are not exclusively planar. In particular, it is understood that a tube 3 extending into a region B and a tube 3' extending out of region B each span a plane En, wherein, with an odd number n of branches, all these planes En are not parallel / different, and with an even number n, as shown here in Figures 8A and 8B, at least two planes En are not parallel / different.

[0093] In other words, the central axis MA of tube 3 before the branch and the central axis MA' of each tube 3' after the branch (which does not correspond to a coaxial tube 3') define a plane En as shown in Figure 8B. In this example, the planes E1 to E6 are defined because there are six branches. Due to the even number n of branches present here, at least two planes are not parallel / different, e.g., the planes E1 and E2, E1 and E6, E1 and E5, etc.

[0094] Because not all spanned planes are the same and / or parallel, the tube structure, especially at each branching point, is understood as not being exclusively planar.

[0095] Figure 9 shows an example of a membrane contactor 2 with a membrane 1 according to the invention as shown in Figures 1 and 2. This contactor has a housing 4 that encloses an exchange chamber, and the individual tubes 3 of the membrane 1 pass through its axial ends. These tubes 3 are connected to connectors 5 with hose nozzles located at the axial end faces of the housing 4. The connectors 5 thus form openings 6 through which a first medium, e.g., blood, can pass through the membrane 1. The connection between the tubes 3 of the membrane 1 and the openings of the housing can also be implemented differently and is shown here only as one possible example.

[0096] The housing 4 has further openings 7 through which a second medium, e.g., an oxygen-containing gas, can be guided through the housing 4 and past the membrane 1 on the outside. The membrane 1 thus divides the exchange chamber inside the housing 4 into two chamber areas. One chamber area is located inside the tubular structure of the membrane, and the other is located outside around the membrane 1.

[0097] Figure 10 shows a modification of the embodiment of Figure 9, in which the second medium, which is guided around the outside of the membrane 1, is introduced into the chamber region of the second medium via an opening 7 and through a lance 8. The lance 8 has an opening open to the central plane ME, e.g. with a diffuser, which leads into a region between two branching planes, in particular between the first and second branching planes.

[0098] Figure 11 further visualizes the procedure according to the preceding general description using a flowchart.

[0099] The process comprises the use of an additive manufacturing process, e.g., 3D printing, wherein in a first alternative the membrane with the tubular structure according to the invention is directly additively manufactured. In the second alternative according to the invention, the manufacturing is carried out indirectly using an additive manufacturing process for producing a manufacturing body, which is then used to manufacture the membrane. The areas marked with dashed lines in the second alternative are optional.

[0100] Insofar as the description of the figures names features relating to a specific number of branches, it should be noted that the features are not limited to this specific number, but apply generally to any number n of branches.

Claims

July 23, 2025 Patent claims 1. Membrane (1) for a membrane contactor (2), characterized in that it is formed as a hollow three-dimensional tube structure lying on both sides of a plane / central plane (ME), in particular a hollow tube structure symmetrical to the plane / central plane with respect to branched tubes (3, 3', 3", 3"', 3""), preferably not exclusively planar branched tubes (3, 3', 3", 3"', 3"") with several branching planes (VE) parallel to the plane / central plane (ME) on both sides of the plane / central plane (ME), wherein the walls of the tube structure are material-permeable and / or energy-permeable and wherein in the region (B) of each branching plane (VE) each tube (3, 3', 3", 3"') extending in the direction of the plane / central plane (ME) branches into several tubes (3', 3", 3"') extending towards the plane / central plane (ME).3"") branches out and the tubes (3"") extending from both sides of the plane / middle plane (ME) from the respective last branching plane (VE) to the plane / middle plane (ME) merge into each other in the area (ÜB) of the plane / middle plane (ME).

2. Membrane (1) according to claim 1, characterized in that on both sides of the plane / middle plane (ME) starting from a single tube (3) the number of tubes (3, 3', 3", 3"', 3"") increases in the direction towards the plane / middle plane (ME).

3. Membrane (1) according to one of the preceding claims, characterized in that within the region (B) of the same branching plane (VE) each tube (3, 3', 3", 3"') extending into the region branches into the same number of tubes (3', 3", 3"', 3"") extending out of the region.

4. Membrane (1) according to one of the preceding claims, characterized in that within the region (B) of the same branching plane (VE) each tube (3, 3', 3", 3'') extending into the region branches into a number of n tubes, wherein n >= 3, preferably n >= 4, preferably n >= 5, further preferably n >= 6.

5. Membrane (1) according to one of the preceding claims, characterized in that within the region (B) of all branching levels (VE) each tube (3, 3', 3", 3"') extending into the region (B) branches into the same number of tubes (3', 3", 3"', 3"") extending out of the region (B).

6. Membrane (1) according to one of the preceding claims, characterized in that a. all tubes (3') resulting from a branching are arranged at an angular distance from each other around a central axis (MA) which penetrates the tube (3) before the branching, preferably that all tubes (3') resulting from a branching are arranged at the same angular distance around a central axis (MA) which penetrates the tube (3) before the branching, or b.that a portion of all tubes (3') arising from a branch are arranged at an angular distance from each other around a central axis (MA) which penetrates the tube (3) before the branch, preferably that a portion of all tubes (3') arising from a branch are arranged at the same angular distance around a central axis (MA) which penetrates the tube (3) before the branch, and that a tube (3MA) arising from the branch is coaxial with the tube (3) before the branch, in particular coaxial with the central axis (MA).

7. Membrane (1) according to claim 6, characterized in that the respective central axis (MA') of at least part of all tubes (3'), preferably of all tubes (3') arising from a branching, in particular extending from the region (B) of a branching plane (VE) in which the branching takes place, in the direction of the central plane (ME), spans a respective plane (El, ..., E6) with the central axis (MA), in particular with the parallel central axis (MA) of the tube (3) before the branching, in particular which extends into the region (B) of a branching plane (VE) in which the branching takes place, in particular wherein each spanned plane (El, ..., E6) is oriented perpendicular to a branching plane (VE), further preferably wherein, in the case of an odd number n of branches, all such spanned planes (El, ..., E6) are not parallel / different to each other or wherein With an even number n of branches, at least two spanned planes (El, E2, ...) are not parallel / different to each other.

8. Membrane (1) according to one of the preceding claims, characterized in that the cross-sectional area / diameter of each tube (3', 3", 3"', 3"") after a branching is smaller than the cross-sectional area / diameter of the tube (3, 3', 3", 3"') before the branching, in particular the cross-sectional area / diameter of the tubes (3, 3', 3", 3"', 3"") decreases with each branching in the direction towards the plane / middle plane (ME).

9. Membrane (1) according to one of the preceding claims, characterized in that the cross-sectional dimension / diameter of each tube (3', 3", 3"', 3"") after each branching is smaller by the same factor than the dimension of the tube (3, 3', 3", 3"') before the branching, at least in the area of ​​the same branching plane (VE), preferably in the areas of all branching planes (VE), in particular by a factor which corresponds to the number of branches or is greater than the number of branches.

10. Membrane (1) according to one of the preceding claims, characterized in that the tube structure is at least partially self-similar / fractal, in particular at least in a region from a first branching to a last branching before the plane / middle plane (ME).

11. Membrane (1) according to one of the preceding claims, characterized in that the tubes (3") merging into one another at the plane / middle plane (ME) cross the plane / middle plane (ME) in a direction perpendicular to the plane / middle plane (ME).

12. Membrane (1) according to one of the preceding claims, characterized in that the tubes (3") merging into one another at the plane / middle plane (ME), in particular those extending towards the plane / middle plane (ME) after the respective last branching plane (VE), have a cross-section deviating from the circular shape, preferably wherein the cross-section of each such tube is star-shaped, preferably star-shaped with at least three arms, preferably with at least four arms, preferably with at least five arms, further preferably wherein the respective arm ends are rounded.

13. Membrane (1) according to one of the preceding claims, characterized in that the area (ÜB) of the transition of the tubes (3") lying on both sides of the plane / middle plane (ME), in particular between the areas of the last branches on both sides of the plane / middle plane (ME), preferably in which the tubes (3") all run parallel to each other and perpendicular to the plane / middle plane (ME), is extended in a direction perpendicular to the plane / middle plane (ME) longer than the minimum distance between two adjacent branching planes (VE) on the same side of the plane / middle plane (ME), preferably also is extended longer than the maximum distance between two adjacent branching planes (VE) on the same side of the plane / middle plane (ME).

14. Membrane (1) according to one of the preceding claims, characterized in that the tubes (3"") in the region (ÜB) of the transition of the tubes (3""), in particular between the regions (B) of the last branches (VE) on both sides of the plane / middle plane (ME), have the smallest cross-section / diameter of all tubes (3, 3', 3", 3"', 3"") of the tube structure, in particular a cross-section / diameter which is in a range of 250 micrometers to 50 micrometers.

15. Membrane (1) according to one of the preceding claims, characterized in that at least one tube (3V") from a branch within a region (B) of a branching plane (VE) extending out of the region (B) towards the plane / middle plane (ME) is connected to another tube (3V") from an adjacent branch within the region (B) of the same branching plane (VE) extending out of the region (B) towards the plane / middle plane (ME), in particular is connected to a common tube.

16. Membrane (1) according to one of the preceding claims, characterized in that the thickness of the membrane (1) decreases in the direction of the plane / middle plane (ME), in particular the thickness is different in the region of each branching plane (VE), preferably wherein the thickness of the membrane (1) in the region of the tubes (3") which cross the plane / middle plane (ME) is in the range of 10 micrometers to 200 micrometers.

17. Membrane (1) according to one of the preceding claims, characterized in that it has an n-angular or (n - l)-angular cross-sectional shape at the plane / middle plane, wherein n corresponds to the number of branches, in particular at all branching planes.

18. Membrane contactor (2) comprising a housing (4) with an exchange chamber, wherein at least one hollow material-permeable and / or energy-permeable membrane (1) is arranged in the exchange chamber, with which the exchange chamber is divided into two chamber regions, wherein a first chamber region adjoins the membrane surface of the hollow membrane (1) on the inside and a second chamber region adjoins the membrane surface of the hollow membrane (1) on the outside, wherein openings (6) are provided on the housing through which a first exchange medium can be guided through the first chamber region, in particular through the interior of the hollow membrane (1), and openings (7) are provided through which a second exchange medium can be guided through the second chamber region, in particular along the outside of the membrane (1), characterized in that the membrane (1) is designed according to one of the preceding claims.

19. Membrane contactor (2) according to claim 18, characterized in that the second medium can be supplied through the wall of the housing (4) by means of a lance (8) into the second chamber area, wherein the open end of the lance (8) lying in the chamber area is located between, preferably centrally between, the branched tubes (3', 3", 3"', 3"") after a branching, in particular after the very first branching.

20. Method for producing a hollow membrane (1) with a tubular structure of multiply branching tubes (3, 3', 3", 3'', 3""), in particular for producing a membrane (1) according to any one of the preceding claims 1 to 17, wherein the production comprises an additive manufacturing process, in particular a 3D printing process, characterized in that the tubular structure is produced indirectly by additive manufacturing, wherein a. by an additive manufacturing process, in particular by 3D printing, a The manufactured body is produced, which corresponds to the internal volume of the part to be manufactured. Tube structure corresponds, and b. the manufacturing body is coated with a coating agent which comprises the material or is formed by the material which forms the membrane, and c. the deposited coating agent forms the tubular structure of the membrane (1) which is supported by the manufacturing body, and d. the manufacturing body is dissolved, in particular after which the tubular structure of the hollow membrane (1) remains.

21. Method according to claim 20, characterized in that a. the coating is carried out by means of a liquid hardenable coating agent, preferably a polymer, in particular the workpiece is immersed in the liquid coating agent, preferably after which excess coating agent is removed, preferably by centrifuging the workpiece, or b. the coating is carried out by depositing the coating agent onto the workpiece from the gas phase.

22. Method according to claim 20 or 21, characterized in that the The manufacturing body is treated prior to coating to make it inactive / inert against a reaction with the coating material, in particular if the manufacturing body is heated and / or exposed to a plasma.

23. Method according to any one of the preceding claims 20 to 22, characterized in that the coated manufacturing body is immersed in or rinsed with a solvent with which the material of the manufacturing body, but not the coating agent, is soluble.

24. Method according to any one of the preceding claims 20 to 23, characterized in that the manufactured body is produced as completely solid, completely hollow, or partially hollow and partially solid.

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