Diffusion device

Abstract

The present disclosure relates to a diffusion device, such as a blood oxygenator or gas exchanger, and a method of manufacturing the same. The diffusion device is used to remove carbon dioxide from blood.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a diffusion device, such as a blood oxygenator or gas exchanger, and a method of manufacturing the same. The diffusion device is used for removing carbon dioxide from blood. BACKGROUND

[0002] Diffusion devices used as blood oxygenators or gas exchangers are known, for example, from DE 102 010 027 973 Al, US 2015 / 10434 Al, EP 0621047 Bl, EP 1108462 A2, or CA 2071850 Al. These devices generally comprise a tubular housing having a plurality of hollow fiber membranes arranged in the housing in such a way as to provide a seal between a first flow space formed by the fiber cavities and a second flow space on the outside surrounding the membranes. The semi-permeable hollow fiber membranes are gas exchange membranes, i.e. they are permeable to gases such as oxygen and carbon dioxide, but not to liquids. In most devices, the semi-permeable hollow fiber membranes are arranged in the form of hollow fiber mats which are wound around a cylindrical core so that the innermost membrane layer directly contacts the core. The flow space formed by the inner cavities of the hollow fibers is separated from the flow space on the outside of the hollow fibers by end walls which are formed by potting the fiber ends with a potting material, such as a polyurethane resin. After the potting material has hardened, the ends of the hollow fibers are cut off to reopen the inner cavities of the hollow fibers.

[0003] The surface of the cylindrical core is not provided with a shape closure by the potting material; moreover, the mat of membranes which directly contacts the core prevents adhesion between the potting material and the core. This reduces the ability of the potting material to withstand mechanical stresses which arise, for example, due to shrinkage of the membranes or thermal expansion under high temperature conditions. As a result, the phenomenon of peeling of the end walls from the core and the formation of leaks can occur.

[0004] It is an object of the present invention to provide a diffusion device which is more resilient against peeling of the end walls from the core. SUMMARY

[0005] The present disclosure provides a diffusion device, such as a blood oxygenator or gas exchanger. The device comprises a tubular housing, a plurality of semi-permeable hollow fiber membranes arranged within the housing, and a plurality of end caps sealing the mouth of the housing. The semi-permeable hollow fiber membranes are arranged in the form of hollow fiber mats which are wound around a cylindrical core. The flow space formed by the inner cavities of the hollow fiber membranes is separated from the flow space on the outside of the hollow fiber membranes by end walls which are composed of a polyurethane resin. According to the present disclosure, the cylindrical core of the diffusion device has features which improve the adhesion of the end walls to the core.

[0006] The present disclosure also provides a method for manufacturing a diffusion device. The method comprises providing a cylindrical core, winding a mat comprising hollow fiber membranes around the core, transferring the wound core into a tubular housing, and potting the ends of the semi-permeable hollow fiber membranes with polyurethane to form end walls that separate the flow space formed by the inner cavities of the hollow fibers from the flow space on the outside of the hollow fibers. According to the present disclosure, the core used has features that improve the adhesion of the end walls to the core. BRIEF DESCRIPTION OF DRAWINGS

[0007] Fig. 1 shows a cross-sectional view and two partial cross-sectional views of a prior art diffusion device;

[0008] Figure 2 Fig. 2 shows a schematic partial cross-sectional view of an embodiment of a diffusion device according to the present disclosure;

[0009] Figure 3 Fig. 3 shows a schematic partial cross-sectional view of another embodiment of a diffusion device according to the present disclosure;

[0010] Figure 4 Fig. 4 shows a schematic partial cross-sectional view of yet another embodiment of a diffusion device according to the present disclosure;

[0011] Figure 5 Fig. 5 shows a schematic top view of an embodiment of a cylindrical core of a diffusion device according to the present disclosure;

[0012] Figure 6 Fig. 6 shows a schematic partial perspective view of another embodiment of a cylindrical core of a diffusion device according to the present disclosure. DETAILED DESCRIPTION

[0013] The present disclosure provides a diffusion device. In one embodiment, the diffusion device is a blood oxygenator. In a particular embodiment, the blood oxygenator is designed for extracorporeal membrane oxygenation (ECMO). In another embodiment, the diffusion device is a gas exchanger. In a particular embodiment, the gas exchanger is designed for removing carbon dioxide from blood in extracorporeal carbon dioxide removal (ECCO2R).

[0014] The device comprises a tubular housing, a plurality of semi-permeable hollow fiber membranes arranged within the housing, and end caps sealing the mouth of the housing. The semi-permeable hollow fiber membranes are arranged in the form of a hollow fiber mat wound on a cylindrical core. The flow space formed by the inner cavities of the hollow fiber membranes is separated from the flow space on the outside of the hollow fiber membranes by end walls, which are composed of polyurethane resin. The end walls are formed by potting the ends of the fibers with polyurethane resin and, after hardening of the resin, cutting off the ends of the fibers to reopen the inner cavities of the fibers.

[0015] In the context of the present disclosure, the term "cylindrical core" does not mean to be limited to strictly cylindrical components, but also includes slightly conical cores with an aperture angle of no more than 5°, for example no more than 3°.

[0016] According to the present disclosure, the cylindrical core of the diffusion device has features that improve the adhesion of the end wall to the core. In one embodiment of the device, the outer surface of the core is coated with a polyurethane resin. In a particular embodiment, the polyurethane coating is present only in the portion of the core that is in contact with the end wall. In another particular embodiment, the outer surface of the cylindrical core is entirely coated with polyurethane.

[0017] In a further embodiment, the outer surface of the core is characterized by at least one circumferential notch in the portion of the core that is in contact with the end wall. In a further embodiment, the outer surface of the core is characterized by at least one circumferential notch in each portion of the core that is in contact with the end wall. In a further embodiment, the outer surface of the core is characterized by at least two circumferential notches in each portion of the core that is in contact with the end wall. The at least one circumferential notch creates a space between the outer surface of the core and the innermost membrane layer. During the potting process, this space is filled with polyurethane, thereby creating a form closure between the potting and the core.

[0018] In a further embodiment, a plurality of elongated noses parallel to the longitudinal axis of the core are located on the outer surface of the core in the portion of the core that is in contact with the end wall. In a further embodiment, the outer surface of the core is characterized by a plurality of elongated noses in each portion of the core that is in contact with the end wall. In one embodiment, the noses are uniformly distributed over the circumference of the core. In one embodiment, the number of noses is in the range of 3 to 16, for example 4 to 8. In one embodiment, the length of the noses in the longitudinal direction is less than the thickness of the end wall. In another embodiment, the length of the noses in the longitudinal direction is greater than or equal to the thickness of the end wall. In one embodiment, the cross-section of the noses is dovetail-shaped. In another embodiment, the cross-section of the noses is mushroom-shaped. In a further embodiment, at least one circumferential ridge is provided on the outer surface of the core in connection with the noses. In a further embodiment, at least two circumferential ridges are provided on the outer surface of the core in connection with the noses. In one embodiment, the width of the at least one circumferential ridge is in the range of 0.5 mm to 2.0 mm. The noses and the circumferential ridges respectively act as spacers between the membrane and the outer surface of the core. During the potting process, the empty spaces are filled with polyurethane, thereby creating a form closure between the potting and the core and providing anchoring for the end wall. Radial displacement of the end wall is inhibited by the noses, while axial displacement of the end wall is inhibited by the circumferential ridges.

[0019] The diffusion device of the present disclosure comprises a tubular housing. In one embodiment, the tubular housing provides an outlet for blood, which is provided on the outer wall of the housing. In a further embodiment, the blood outlet is located near the end of the tubular housing opposite the first end cap. In one embodiment, the tubular housing is composed of polycarbonate.

[0020] A plurality of semi-permeable hollow fiber membranes are provided within the housing, between the outer surface of the core and the inner wall of the housing. In one embodiment, the semi-permeable hollow fiber membranes are gas exchange membranes, i.e. they are permeable to gases like oxygen and carbon dioxide, but not to liquids.

[0021] The semi-permeable hollow fiber membranes are provided in the form of a hollow fiber mat that is wound around the cylindrical core. The hollow fiber mat forms a cylindrical shell that contacts the inner surface of the tubular housing. The ends of the hollow fibers are left open, so that a gas flow can be directed through the interior lumen of the hollow fibers, i.e. from one mouth of the housing to the mouth opposite thereto. During operation of the diffusion device, blood flows on the outside of the hollow fibers, while gas can permeate through the wall of the hollow fibers in both directions. The flow space formed by the interior lumen of the hollow fibers is separated from the flow space on the outside of the hollow fibers by end walls. These end walls are formed by potting the fiber ends with a polyurethane resin. After the resin has hardened, the ends of the hollow fibers are cut off to reopen the interior lumen of the hollow fibers.

[0022] The diffusion device comprises a first end cap that seals the first mouth of the housing. The end cap comprises an inlet for introducing blood into the housing, which is provided axially in the center of the first end cap. In one embodiment, a two-start thread that cooperates with a standard blood line connector is provided around the inlet. The inner surface of the end cap is rotationally symmetric about the longitudinal axis of the inlet. The inlet is also coaxial with the longitudinal axis of the housing. In a further embodiment, the end cap further comprises an outlet for expelling gas, e.g. a gas mixture comprising carbon dioxide, from the diffusion device.

[0023] One embodiment of the diffusion device of the present disclosure additionally comprises a second end cap that seals the second mouth of the housing, i.e. the mouth opposite the mouth of the first end cap. The second end cap provides an inlet for introducing a gas, e.g. air or oxygen, into the diffusion device.

[0024] In one embodiment, the housing and end caps of the device of the present disclosure are made of a transparent polymer, for example including: a polyolefin (e.g. polyethylene or polypropylene); a polyester, for example PET, PBT, or polycarbonate; polystyrene (HIPS); or a polymethyl(meth)-acrylate. In one embodiment, the housing and end caps are made of polycarbonate, while the potting material forming the end walls consists of polyurethane. In one embodiment, the cylindrical core is constructed of a thermoplastic polymer. In a particular embodiment, the cylindrical core is constructed of polycarbonate. In one embodiment, the cylindrical core is manufactured by injection molding.

[0025] The present disclosure also provides a method for manufacturing a diffusion device. The method comprises: providing a cylindrical core; wrapping a mat comprising hollow fiber membranes around the core; transferring the wrapped core into a tubular housing; and potting the ends of the semi-permeable hollow fiber membranes with polyurethane to form end walls that separate the flow space formed by the lumens of the hollow fibers from the flow space on the outside of the hollow fibers. According to the present disclosure, the core used has features that improve the adhesion of the end walls to the core.

[0026] In one embodiment, the outer surface of the cylindrical core is coated with a polyurethane resin prior to wrapping the mat of hollow fiber membranes around the cylindrical core. In a particular embodiment, the polyurethane coating is present only in the portion of the core that contacts the end walls. In another particular embodiment, the outer surface of the cylindrical core is entirely coated with polyurethane.

[0027] In a further embodiment, the cylindrical core is characterized by a plurality of circumferential notches in the portion of the cylindrical core that contacts the end walls on the cylindrical core.

[0028] In a further embodiment, a plurality of elongated noses parallel to the longitudinal axis of the cylindrical core are located in the portion of the cylindrical core that contacts the end walls on the cylindrical core. In one embodiment, the cross-section of the nose is dovetail-shaped. In another embodiment, the cross-section of the nose is mushroom-shaped. In a further embodiment, the outer surface of the core is characterized by a peripheral ridge connecting the noses.

[0029] After the end walls are formed in the potting step, the ends of the hollow fiber membranes are cut off with a transverse incision to reopen the lumens of the hollow fiber membranes. End caps are then mounted on both ends of the tubular housing to close the mouths of the housing; and the end caps are welded or glued to the housing to seal the diffusion device.

[0030] The diffusion device of the present disclosure will now be described in more detail with reference to the accompanying drawings. It is to be understood that the drawings are not intended to limit the scope of the present disclosure but merely constitute preferred embodiments of the device.

[0031] Figure 1 shows a cross-sectional view of a prior art diffusion device 100. Also shown are enlarged detail views X and Y of the device. The mouth of the tubular housing 110 is covered by a first end cap 130 and a second end cap 500. The housing 110 has a blood inlet 115 located on the outer wall of the housing adjacent to the second end cap 500. The first end cap 130 is characterized by a blood inlet 131 and a gas outlet 132, and the second end cap 500 is characterized by a gas inlet 501. Hollow fibers 120 are disposed within the housing 110 around a cylindrical core 150. An end wall 400 separates a first flow space, formed by the lumina of the hollow fibers 120 and the cavity defined by the second end cap 500 and the first end cap 130, from a second flow space, defined by the blood inlet 131, a blood conduit 140, and the space outside the hollow fibers 120 and between the inner wall surface of the housing 110 and the outer wall surface of the core 150. The core 150 is formed from an assembly of two component parts 301 and 302. The component part 301 is characterized by four recesses 310, and the component part 302 has four corresponding protrusions 311. The protrusions 311 enter the recesses 310 when the core is assembled and together form the blood conduit 140, with the component part 301 defining a first surface 141 of the blood conduit 140, and the component part 302 defining a second surface 145 of the blood conduit 140.

[0032] Figure 2 Figure 4 shows a schematic partial cross-sectional view of an embodiment of a diffusion device of the present disclosure. Shown is the head portion of the device having an end wall 400. At the interface of the end wall 400 and the cylindrical core 150, a polyurethane layer 151 is provided. The polyurethane layer 151 improves the adhesion of the embedded end of the end wall 400 and the hollow fiber 120 to the cylindrical core 150.

[0033] Figure 3 Figure 5 shows a schematic partial cross-sectional view of another embodiment of a diffusion device of the present disclosure. Shown is the head portion of the device having an end wall 400. In the portion of the cylindrical core 150 that is in contact with the end wall 400, the cylindrical core 150 is characterized by a circumferential notch 152. During the potting of the hollow fiber membrane 120 and the formation of the end wall 400, the circumferential notch 152 is filled with polyurethane. The polyurethane-filled circumferential notch 152 improves the adhesion of the end wall 400 to the cylindrical core 150.

[0034] Figure 4 Figure 6 shows a schematic partial cross-sectional view of yet another embodiment of a diffusion device of the present disclosure. In contrast to the embodiment shown in Figure 5, two circumferential notches 152 are provided in the portion of the cylindrical core 150 that is in contact with the end wall 400. Figure 3

[0035] Figure 5 ​A schematic top view showing one embodiment of a cylindrical core 150 of a diffusion device of the present disclosure. The cylindrical core 150 is characterized by a plurality of dovetail noses 153 in the portion of the cylindrical core 150 that is in contact with the end wall. In the embodiment shown, eight dovetail noses 153 are evenly distributed on the circumference of the cylindrical core 150. Figure 5 In the embodiment shown, eight dovetail noses 153 are evenly distributed on the circumference of the cylindrical core 150.

[0036] Figure 6 A schematic partial perspective view showing another embodiment of a cylindrical core of a diffusion device of the present disclosure. Shown is only one of the two head portions of the cylindrical core 150. As in the embodiment of Figure 5 The cylindrical core 150 is characterized by a plurality of dovetail noses 153 in the portion of the cylindrical core 150 that is in contact with the end wall. In the embodiment shown, four dovetail noses 153 are evenly distributed on the circumference of the cylindrical core 150. In addition, two circumferential ridges 154 are provided in the portion of the cylindrical core 150 that is in contact with the end wall. The circumferential ridges 154 act as anchors for the end wall to prevent axial displacement of the end wall. Figure 6 In the embodiment shown, eight dovetail noses 153 are evenly distributed on the circumference of the cylindrical core 150.

[0037] List of reference signs:

[0038] 100 diffusion device

[0039] 110 tubular housing

[0040] 115 blood outlet

[0041] 120 hollow fiber membrane

[0042] 130 first end cap

[0043] 131 blood inlet

[0044] 132 air outlet

[0045] 140 blood conduit

[0046] 141 first inner surface

[0047] 145 second inner surface

[0048] 150 cylindrical core

[0049] 151 polyurethane layer

[0050] 152 circumferential notch

[0051] 153 nose

[0052] 154 circumferential ridge

[0053] 301 first component part

[0054] 302 second component

[0055] 310 recess

[0056] 311 protrusion

[0057] 400 end wall

[0058] 500 second end cap

[0059] 501 air inlet

Claims

1. A diffusion device (100) comprising: Tubular housing (110); a plurality of semi-permeable hollow fiber membranes (120) disposed on a cylindrical core (150) within the tubular housing (110); a plurality of end walls (400) composed of polyurethane resin, which separate a flow space formed by the inner cavities of the hollow fiber membranes (120) from a flow space on the outside of the hollow fiber membranes (120); and a first end cap (130) and a second end cap (500) sealing the mouth of the tubular housing (110), characterized in that the cylindrical core (150) has features that increase the adhesion of the end walls (400) to the cylindrical core (150), namely, the outer surface of the cylindrical core (150) is characterized by a plurality of elongated noses (153) parallel to the longitudinal axis of the cylindrical core (150) and located on the outer surface of the cylindrical core (150) in the portion of the cylindrical core (150) that is in contact with the end walls (400) of the cylindrical core (150), and at least one peripheral ridge (154) connecting the noses (153) is disposed on the outer surface of the cylindrical core (150) in the portion of the cylindrical core (150) that is in contact with the end walls (400) of the cylindrical core (150). The noses (153) are uniformly distributed on the periphery of the cylindrical core (150), and the length of the noses (153) in the longitudinal direction is less than the thickness of the end walls (400).

2. Diffusion device (100) according to claim 1, wherein The cross section of the noses (153) is dovetail-shaped.

3. Diffusion device (100) according to claim 1 or 2, wherein At least two peripheral ridges (154) connecting the noses (153) are disposed on the outer surface of the cylindrical core (150) in the portion of the cylindrical core (150) that is in contact with the end walls (400) of the cylindrical core (150).

4. The diffusion device (100) according to claim 1, wherein a) providing a cylindrical core (150); 5. A method for manufacturing a diffusion device, comprising the steps of: ​ b) winding a mat comprising hollow fibre membranes (120) around the cylindrical core (150); c) transferring the wound cylindrical core (150) into a tubular housing (110); and d) potting the ends of the semi-permeable hollow fibre membranes (120) with polyurethane to form end walls (400) separating the flow space formed by the inner cavities of the hollow fibre membranes (120) from the flow space on the outside of the hollow fibre membranes (120), characterized in that the cylindrical core (150) has features that increase the adhesion of the end walls (400) to the cylindrical core (150), i.e. the outer surface of the cylindrical core (150) is characterized by a plurality of elongated noses (153) that are parallel to the longitudinal axis of the cylindrical core (150) and that are located on the outer surface of the cylindrical core (150) in the part of the cylindrical core (150) that is in contact with the end walls (400) of the cylindrical core (150), and at least one circumferential ridge (154) connecting the noses (153) is provided on the outer surface of the cylindrical core (150) in the part of the cylindrical core (150) that is in contact with the end walls (400) formed in step d).

6. The method of claim 5, wherein, Before step b), the cylindrical core (150) is coated with polyurethane.

7. The method of claim 6, wherein, Only the part of the cylindrical core (150) that will be in contact with the end walls (400) formed in step d) is coated with polyurethane.

8. The method of any one of claims 5-7, wherein, The noses (153) are dovetail-shaped.

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