Overmolded bulkhead

Abstract

Disclosed herein is a puncturable septum (1) for use in drug reservoirs and infusion sets. The puncturable septum (1) comprises an elastic core (11) from a core material and a periphery (10) from a periphery material, the periphery material being more rigid than the core material. The elastic core (11) is entirely embedded within the periphery (10).

Description

Technical Field

[0003]

[0001] The present invention belongs to the technical field of infusion or injection. More specifically, it relates to a pierceable septum as used in an infusion set or reservoir for liquid drugs, an infusion set and reservoir comprising the septum, and a method for manufacturing a pierceable septum.

Background Art

[0002] Walking infusion sets are well known in the art. For example, in the treatment of diabetes, a walking infusion set is used in combination with a miniaturized infusion pump for continuous subcutaneous insulin infusion (CSII), where a small amount of drug is metered and injected into the patient's tissue through a cannula. Such infusion sets can also be used in several further treatments, such as pain treatment or cancer treatment. Infusion sets are available from several suppliers, such as Roche Diabetes Care GmbH in Germany or Medtronic MiniMed Inc. in California, USA. For example, in CSII, the metered dose is in the range of microliters or nanoliters.

[0003] Typical infusion sets and systems are usually operated in a continuous manner and therefore always carried by the patient, but there are some daily routines such as showering and swimming where the pump and piping must be removed. In such cases, leaving the cannula unit with the patient without removing the flexible infusion cannula used to introduce the drug into the patient's tissues is beneficial for the patient's interest and for cost reasons. Therefore, infusion systems have been developed that feature a cannula unit that can be easily disconnected from the rest, especially the piping, by disconnecting the connector device. The connector device comprises a connector cannula that fluidly connects to the piping and infusion pump. However, with each reconnection, the septum of the cannula unit is perforated by the connector cannula. As a result, the septum suffers multiple cuts from the sharp cannula commonly used and therefore becomes more prone to leakage.

[0004] A wide variety of infusion sets for introducing liquid drugs into a patient's body rely on elastic septa that can be repeatedly punctured by a cannula or needle. A typical infusion set may comprise a cannula unit that can be fluidly connected to an infusion pump and / or drug reservoir via piping, for example, using a connector device with a connector cannula. Typically, the cannula unit further comprises a compartment for the liquid drug, at least partially formed by the surface of a septum. In particular, a septum may be used to seal this compartment, which is essentially permanently fluidly connected to the patient's tissue via the infusion cannula. In such a system, the liquid drug can be transferred to the compartment and subsequently to the patient via the connector cannula and infusion cannula.

[0005] Furthermore, with respect to the infusion set, it is advantageous to employ a flexible infusion cannula to establish a permanent fluid connection to the patient's tissue. Such a flexible infusion cannula is inserted into the patient's tissue with the help of a puncturing needle, such as a rigid steel needle, with one section of the puncturing needle initially positioned within the lumen of the infusion cannula, while the head section is positioned above the septum, and the puncturing needle penetrates the septum. After both the puncturing needle and the flexible infusion cannula are inserted into the tissue, the puncturing needle is retracted, while the flexible infusion cannula remains in the tissue. Either a single septum is used for both drug delivery and puncturing needle introduction, or two different septums may be employed instead. Typical examples are described in International Patent Publication 02 / 07804 A1, U.S. Patent Application Publication 2012 / 296290 A1, and European Patent Application 2528642 A2.

[0006] To prevent leakage of liquid drugs and to avoid external contamination, these septa are generally shaped cylindrically and prestressed by radial compression. In these systems, the septum is incorporated into the cannula housing, which compresses the septum. A further advantageous effect of radial compression is that after the penetration and subsequent removal of the needle or cannula, the resulting channel-shaped cut within the septum is compressed, beneficially preventing or at least mitigating leakage.

[0007] As described above, one possible approach to achieving this goal is to prestress the partition wall by radial compression. However, due to structural constraints, the compressive force cannot be increased indefinitely. Importantly, while radial compression of the partition wall effectively reduces leakage of the liquid drug in cases where the partition wall is punctured only once, leakage becomes a problem when the puncture event is repeated. Furthermore, typical infusion systems employ an infusion pump, which delivers liquid medication to the patient, thus applying fluid pressure. As a result of this fluid pressure, leakage becomes a serious problem, especially if the septum has already been punctured multiple times.

[0008] Furthermore, multilayer partitions are known in the art. These partitions are manufactured by the separate fabrication of at least two layers, which may be made of different materials and subsequently joined to form a laminate. Typically, cylindrical partitions are then obtained by punching out the laminate. [Overview of the Initiative]

[0009] Due to the manufacturing process described above, multilayer partitions are severely limited in their design. Typically, equipping these partitions with functional geometric shapes, such as sealing lips, is impossible because these manufacturing methods inevitably produce thin, disc-shaped partitions. Furthermore, the lamination step induces internal tension within the material, which leads to leakage when the partition is penetrated using a cannula. The final punching of the lamination compresses the partition before it is punched out of the lamination. As a result, when the partition is finally punched out, its sides are somewhat uneven and not perfectly symmetrical. When such partitions are used, for example, in an infusion set, leakage between the partition and the housing often occurs. Therefore, while multilayer partitions may be suitable to reduce leakage between the cannula and the partition, these often lead to leakage between the partition and the housing of the infusion set.

[0010] In particular, multiple punctures using cannulas still represent a significant source of leakage. This is a major problem, firstly, because in cases of small dose units in the nanoliter range, which are typically used in continuous insulin infusion, any undetected leakage can have a dramatic impact on the dosage and therefore on the patient's health. Secondly, many automated infusion devices are equipped with occlusion detection devices, which can malfunction when operating in an untight system.

[0011] Accordingly, the overall objective of the present invention is to improve the state of art regarding the design and use of elastic septa in the context of liquid drug infusion and / or injection, thereby preferably all or partly avoiding the drawbacks of the prior art. The septa may belong to an infusion set, particularly when used in, for example, a CSII or drug reservoir.

[0012] In beneficial embodiments, the improved partition provides a tight seal even when repeatedly punctured and / or exposed to higher pressures.

[0013] Furthermore, in beneficial embodiments, the partition can be manufactured in a cost-effective manner.

[0014] The overall objective is generally achieved by the subject matter of the independent claims. Further advantageous and exemplary embodiments are derived from the independent claims, specification, and drawings.

[0015] According to a first aspect of the present invention, the overall objective is achieved by a perforated partition for use in drug reservoirs and infusion sets. The partition comprises an elastic core from a core material and a peripheral portion from a peripheral material. In addition, the elastic core is embedded entirely within the peripheral portion, and the peripheral material is more rigid than the core material.

[0016] Since the elastic core is entirely embedded within the surrounding material, the core is completely covered by the surrounding material and therefore not exposed at the surface of the partition wall. This offers the advantage of significantly limiting the tensile behavior of the core material. In contrast to partition walls where the elastic core is not entirely embedded within the surrounding material, the elongation of the elastic core during penetration of the partition wall by the cannula is limited from all sides of the elastic core. Because the surrounding material is more rigid than the core material, a radially oriented force acts on the core material toward the penetrating cannula. As a result, any gaps between the cannula and the partition wall are avoided, and the interface between the cannula and the partition wall is tightly sealed.

[0017] As used herein, the term “septum” will be readily understood by those skilled in the art, and it is a typically industrially manufactured element, such as a membrane or plug, that can be punctured by a needle or cannula, for sealing a first side and a second side of a fluid, i.e., for airtight and / or liquidtight sealing. Typically, a septum does not include an opening or puncture passing through the septum from the first side to the second side before a needle or cannula punctures through the septum. Consequently, a stump needle cannot easily puncture through the septum without applying considerable force.

[0018] The partitions can typically be made from elastomer materials and / or thermoplastic elastomer materials, such as silicone rubber or natural rubber and rubber derivatives (i.e., isoprene rubber, butyl rubber, FKM, styrene-butadiene rubber, etc.).

[0019] The perforated partitions for use in drug reservoirs and infusion sets according to the present invention are essentially cylindrical or cubic. Preferably, the partitions have an essentially flat, plate-like shape. In this context, the term "essentially" is understood to include partitions having, for example, one or more sealing lips and / or circumferential grooves.

[0020] The elastic core may preferably have a cubic shape. However, the core may be spherical or have any other suitable shape. Typically, the elastic core is flat and elongated in the direction of the septum. The direction of the septum is perpendicular to the puncture path of the cannula.

[0021] The perforable partition according to the present invention may typically have a diameter or width of 2 to 20 mm, preferably 2 to 6 mm, and more preferably 3 to 4 mm.

[0022] Typically, the thickness of the septum, i.e., the distance that needs to be drilled while the cannula is in an operable state, is 1 to 10 mm, preferably 1 to 5 mm, more preferably 1 to 2 mm.

[0023] Furthermore, those skilled in the art understand how to determine whether the first material is more rigid than the second material. For example, this may be achieved by measuring and comparing the Shore hardness of the materials. Typically, in the art, a Shore hardness tester is generally used for this purpose. The higher the Shore hardness of the material, the greater the resistance to indentation, and thus the harder the material. Therefore, a more rigid material is also a harder material. This difference in rigidity between the core material and the surrounding material presents the advantage that, when the cannula is withdrawn, filling may be generated at the cut portion of the channel shape caused by the puncture of the needle. Due to this filling, the sealing of the septum is significantly increased and leakage is avoided.

[0024] In a typical embodiment, the elastic modulus of the core material is smaller than the elastic modulus of the surrounding material.

[0025] Preferably, in this specification, the rigidity modulus is used as the elastic modulus. In an embodiment according to the present invention, the elastic restoring force of the core is smaller than the elastic restoring force of the surrounding portion. As is known to those skilled in the art, the elastic restoring force is directly affected by the hardness and / or elastic modulus of the layer. In such embodiments, filling may be generated within the cut portion of the channel shape caused by the puncture of the needle when the cannula is withdrawn.

[0026] Typically, the drillable septum is integrally designed, i.e., the elastic core and the surrounding portion are fixedly connected to each other.

[0027] In a preferred embodiment, the surrounding material has a Shore hardness selected such that the extension of the core material during penetration of the septum using the cannula is limited.

[0028] In other embodiments, the peripheral material has a Shore hardness of 0 to 100 Shore A, preferably 50 to 80 Shore A, and / or the core material has a Shore hardness of 0 to 50 Shore A, preferably 10 to 40 Shore A. Such hardness is particularly advantageous because the outer material is rigid enough to provide an efficient limitation of the core material's elongation, thereby effecting a tight seal associated with cannula removal.

[0029] In a preferred embodiment, the elastic core of the pierceable septum is overmolded by the peripheral portion. This has the advantage that the elastic core and the peripheral portion are fixedly connected without using any additional adhesives.

[0030] In a further embodiment, the core material is an elastomer and / or the peripheral material is an elastomer and / or a thermoplastic elastomer. For example, in certain embodiments, a mixture of an elastomer and a thermoplastic elastomer may be used. One example includes a mixture of silicone and a thermoplastic elastomer.

[0031] In a further embodiment, the elastic core is pre-stressed radially by the peripheral portion. The term "radial compression" as used herein refers to the force applied towards the axis that intersects the piercing path of the cannula, i.e., the center of the first surface of the septum and the center of the opposite second surface. In these embodiments, the peripheral portion is constructed in a manner that pre-stresses the core by radial compression. Therefore, the sealing of the interface between the penetrating needle and the septum is further improved. These embodiments improve the state of the art regarding the design of elastic septa in the context of liquid drug infusion and / or injection, as leakage is effectively avoided or at least significantly reduced.

[0032] In a preferred embodiment, the partition wall additionally includes at least one sealing lip, which also helps to prevent leakage. Alternatively, or in addition, the partition wall may include a circumferential groove. When a higher pressure is applied to the first surface having the circumferential groove of such embodiments in the operating state compared to the second surface on the opposite side, (i) The axial component of the force applied to the first surface acts toward an axis intersecting the center of the first surface and the center of the second surface, (ii) The edge-direction component of the force applied to the first surface acts in the opposite direction to the axis intersecting the center of the first surface and the center of the second surface.

[0033] Therefore, the circumferential groove further reduces leakage at the interface between the puncture cannula and the septum, at the through-cut portion remaining after the cannula is removed, and at the interface between the cannula housing and the septum.

[0034] In other embodiments, the periphery may comprise two or more different materials. For example, the rigidity of the material along the cannula's puncture path may be less than that of the material away from the puncture path. Therefore, in such embodiments, the fully embedded elastic core may be surrounded by at least two different materials. In these embodiments, the elastic core material is the least rigid material, the periphery material away from the cannula's puncture path is the most rigid material, while the rigidity of the periphery material within the puncture path is somewhere in between. The puncture path may be indicated by optical or tactile means. According to another aspect of the present invention, a method for manufacturing a punctureable partition is provided. The method comprises the steps of providing an elastic core from a core material and overmolding the elastic core collectively with a periphery material to manufacture a punctureable partition having an elastic core, wherein the elastic core is collectively embedded within the periphery.

[0035] In a preferred embodiment, the overmolding is carried out by injection molding, preferably by 2k molding.

[0036] According to a further aspect of the present invention, the overall objective is achieved by an injection set comprising a perforable partition according to the present invention.

[0037] Typically, the partitions within an injection set are pre-stressed radially by radial compression.

[0038] According to a further aspect of the present invention, the overall objective is achieved by a reservoir for liquid drugs having a perforable partition according to the present invention.

[0039] Typically, the partitions within a drug reservoir are pre-stressed radially by radial compression. [Brief explanation of the drawing]

[0040] [Figure 1] A cross-sectional view of a perforated partition wall according to one embodiment of the present invention is shown. [Figure 2] A cross-sectional view of a perforated partition wall according to another embodiment of the present invention is shown. [Figure 3] A cross-sectional view of a perforated partition wall according to another embodiment of the present invention is shown. [Figure 4] A cross-sectional view of a perforated partition wall according to another embodiment of the present invention is shown. [Figure 5(a)] A cross-sectional view of a perforated partition wall incorporated into a housing according to another embodiment of the present invention is shown. [Figure 5(b)] A cross-sectional view of a perforated partition wall incorporated into a housing according to another embodiment of the present invention is shown. [Figure 6] This shows a cross-sectional view of a perforated partition incorporated into a drug reservoir according to another embodiment of the present invention. [Modes for carrying out the invention]

[0041] Exemplary Embodiments An advantageous embodiment of the perforated partition wall 1 according to the present invention is shown in Figure 1. The perforated partition wall 1 comprises an elastic core 11 from a core material and a perimeter 10 from a perimeter material. As is readily apparent, the elastic core is entirely embedded within the perimeter. In other words, the elastic core is entirely disposed inside the perimeter. Therefore, the elastic core is invisible, does not extend to the surface of the partition wall, and cannot come into contact with any other components such as the housing or drug reservoir. The elastic core in the shown embodiment is essentially flat and elongated laterally along the partition wall.

[0042] Figure 1 also illustrates axis A, which extends along the cannula's puncture path and is essentially perpendicular to the lateral direction of the septum.

[0043] Figure 2 illustrates another embodiment of the invention. In addition to the elastic core 11 and the surrounding portion 10, the perforated partition wall 1 further comprises a circumferential groove 12 (for clarity, the core and surrounding portion are not filled in as in Figure 1). Typically, when such a partition wall is used in an infusion set or drug reservoir, the surface of the partition wall with the groove 12 faces the inside of the infusion set or drug reservoir, and the opposite flat surface faces the outside of the infusion set or drug reservoir.

[0044] Figure 3 shows the partition wall 1 according to the present invention, which is penetrated along the drilling path by the cannula 21. As indicated by the arrow, the peripheral portion 10 applies a force F2 to the elastic core 10, at which point the elastic core engages the cannula in a sealed manner (F1). Therefore, the partition wall according to the present invention may significantly increase friction between the cannula and the partition wall.

[0045] Figure 4 illustrates a further advantageous embodiment of the perforable partition wall 1 according to the present invention. The periphery 10 comprises two different materials. The rigidity of the material along the cannula's perforation path (see 10a) may be less than that of the material away from the perforation path (see 10b). As a result, the elastic core 11 is surrounded by the two different materials. Such embodiments have the advantage of providing the aforementioned sealing effect by laterally engaging the penetrating cannula while allowing for smooth perforation of the partition wall along a predetermined perforation path.

[0046] Figure 5(a) illustrates a perforated partition 1 according to the present invention, incorporated into a housing unit 20. The housing unit 20 is part of a cannula unit 25, which itself may be part of an infusion set. In addition, the cannula unit 25 may include a flexible infusion cannula 23 that can be inserted into the patient's tissue by inserting a perforating needle through the partition before assembly of a removable connector device 24. As is readily apparent, the housing unit 20 and the partition form a compartment 22 that may contain a liquid drug. For example, the drug can be delivered into the compartment 22 under pressure by an infusion pump (not shown) which is fluidly connected to a connector cannula 21. The connector cannula 21 is part of a connector device 24, which is removablely connected to the cannula unit 25 and is not shown in detail. The state shown in Figure 5(a) represents the operational state of the injection set, where the injection pump is fluid-connected to the flexible injection cannula 21 via the compartment 22 and the connector cannula 21.

[0047] Figure 5(b) shows the cannula unit 25 of Figure 5(a), where the user may disconnect the infusion pump from the connector device 24 by withdrawing the connector cannula 21 from the partition 1. This process may be performed by the user in situations where the infusion pump may be unsuitable, for example, while taking a shower. Withdrawing the connector cannula 21, as shown by the curved line, leaves a puncture or penetrating cut within the partition. Due to the fact that the surrounding material is more rigid than the core material, and due to the difference in elastic modulus between the elastic core 11 and the surrounding 10, a compensation is generated in the penetrating cut, i.e., the penetrating cut is not continuous, and the penetrating cut in the core 11 is laterally offset compared to the penetrating cut in the surrounding 10. This compensation significantly reduces the occurrence of any leakage, which is all the more important in the case of multiple punctures.

[0048] Figure 6 shows a drug reservoir 20, such as an insulin cartridge, comprising a wall 31 and a liquid drug 32. The perforated partition 1 according to the present invention allows the drug 32 to be withdrawn from the reservoir by a cannula and ensures a tight seal of the perforated partition 1 during and after the cannula is inserted. The specific partition 1 shown comprises a core 11 that is embedded throughout the surrounding portion 10.

Claims

1. A perforated partition (1) for use in drug reservoirs and infusion sets, comprising an elastic core (11) from a core material and a peripheral portion (10) from a peripheral material, wherein the elastic core (11) is entirely embedded within the peripheral portion (10), and the peripheral material has a higher Shore hardness than the core material. The surrounding portion (10) comprises two different surrounding materials, wherein the Shore hardness of the first surrounding material along the drilling path of the cannula is lower than that of the second material away from the drilling path of the cannula. A partition wall that can be perforated (1).

2. The perforable partition wall (1) according to claim 1, wherein the surrounding material has a Shore hardness selected such that the elongation of the core material is limited when the partition wall (1) is penetrated by a cannula.

3. The perforated partition (1) according to claim 1 or 2, wherein the surrounding material has a Shore hardness of 0 to 100 Shore A, preferably 50 to 80 Shore A, and / or the core material has a Shore hardness of 0 to 50 Shore A, preferably 10 to 40 Shore A.

4. The perforated partition (1) according to any one of claims 1 to 3, wherein the elastic core (11) is overmolded by the surrounding portion (10).

5. The perforated partition (1) according to any one of claims 1 to 4, wherein the core material is an elastomer and / or the surrounding material is an elastomer or a thermoplastic elastomer.

6. The perforated partition wall (1) according to any one of claims 1 to 5, wherein the elastic core (11) is pre-stressed radially by the surrounding portion (10).

7. The perforable partition wall (1) according to any one of claims 1 to 6, wherein the partition wall (1) comprises a sealing lip or a circumferential groove (12).

8. An injection set comprising a perforable partition (1) as described in any one of claims 1 to 7.

9. The injection set according to claim 8, wherein the partition wall (1) is given pre-stress in the radial direction by radial compression.

10. A reservoir (30) for liquid drugs, comprising a perforable partition (1) according to any one of claims 1 to 7.

11. The reservoir (30) according to claim 10, wherein the partition wall (1) is given pre-stress in the radial direction by radial compression.

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