HK40069784A - Injection molded cannula system - Google Patents

Description

Injection molded cannula system

Technical Field

The invention belongs to the technical field of infusion. More particularly, the present invention relates to infusion site interfaces and infusion pumps, and methods of manufacturing cannula systems for infusion site interfaces.

Background

Infusion pumps are used to parenterally provide liquid medication to a patient over an extended period of time. Infusion pumps are available today that are of very small size and can be carried on the body by the patient. Such small-sized ambulatory infusion pumps are particularly useful for metering small doses of highly effective liquid medicaments, such as insulin for the treatment of diabetes, or analgesics for pain management, which are delivered through a cannula into the tissue of a patient.

In one approach, an infusion pump carried somewhere on the body (e.g., attached to a belt) is fluidly connected via flexible tubing to an infusion site interface (also referred to as an insertion head) that is attached to the body of the patient. The infusion site interface includes a cannula system having a cannula to be inserted into body tissue, a housing, and a connector device for fluidly connecting the cannula with a flexible tubing connected to an upstream infusion pump. The tubing may be repeatedly connected and disconnected from the infusion site interface. The connector device may, for example, comprise a septum of a fluid system enclosing the cannula and the housing. The septum may be penetrated by a hollow needle for reversibly establishing a fluid connection. The cannula is preferably made of a flexible material and is therefore a soft cannula. Such a cannula is more comfortable for its user, especially during body movements. Since the flexible cannula cannot be inserted directly into the tissue, an additional puncture device is arranged inside the flexible cannula, for example in the form of a rigid puncture needle made of metal. The pointed end of the puncture device protrudes from the proximal end of the cannula that is to be opened towards interstitial fluid. After inserting the puncture device and the stabilized cannula into the body tissue, the rigid puncture device is removed from the flexible cannula. The flexible cannula remains in the body tissue. Generally, the puncture needle is arranged in such a way that it penetrates a septum that seals the distal end of the now open cannula fluid path after the puncture needle is withdrawn.

In another approach, the infusion pump device is in direct fluid connection with the infusion site interface. The fluid connection between the pump and the cannula is established by a hollow connector needle of the pump which reversibly penetrates the septum of the cannula unit, wherein the septum closes the distal end of the cannula fluid path. Advantageously, the pump may be repeatedly connected and disconnected from the infusion site interface.

In a common method of manufacturing an infusion site interface with a soft and flexible cannula, a stabilizing pin is introduced into the flexible cannula in a first step to simplify handling of the flexible cannula during the manufacturing process. The temporary structural unit prepared in this way is inserted into a prefabricated housing, the flexible cannula and the housing being permanently connected, for example by heat treatment. The stabilizing pin is then withdrawn from the flexible cannula and replaced by the actual puncturing device. Insertion of the puncture device sometimes damages the flexible cannula, which can lead to a relatively high rejection rate during manufacturing.

WO 2018033614 a1 discloses a cannula unit comprising a housing and a flexible cannula. The flexible cannula is provided with an end region deviating from the shape of the rest of the flexible cannula. The end region of the flexible cannula has for example a funnel shape or a flange shape. Furthermore, the housing comprises two parts between which the end region of the flexible cannula is securely locked to the housing by clamping. The two parts of the housing are finally joined by welding, in particular laser welding.

Disclosure of Invention

The cannula units and systems known in the prior art have certain drawbacks. For example, there are certain limitations if the cannula unit comprises a housing with two parts that are produced separately and only subsequently connected during the manufacturing process. First, the material must be suitable for welding or gluing so that the two housing parts can be connected. Second, the joining step represents an additional step, which increases manufacturing time and production costs. Third, the two parts of the housing must be strictly complementary, thus allowing only small material tolerances, otherwise leakage can be a problem. This is a serious problem in the prior art, since the number of defective products due to non-complementary housing parts is very large.

It is therefore a general object of the present invention to improve the prior art regarding the design and use of cannula systems in case of infusion of liquid drugs, preferably avoiding the drawbacks of the prior art in whole or in part.

In an advantageous embodiment, a cannula unit is provided in which the occurrence of leakage is avoided or at least significantly reduced.

In a further advantageous embodiment, a cannula unit is provided which can be manufactured in a time and cost efficient manner.

In a further advantageous embodiment, the number of defective products and thus the reject rate during the manufacturing process is reduced.

According to a first object of the present invention, the general object is achieved by a method for manufacturing a cannula system having a body unit and a compression unit. The method includes providing a body unit including a mounting structure, the body unit being mounted to a mold core pin. The soft cannula is then mounted on the mounting structure of the body unit. In a next step, the compression unit is injection molded over the soft cannula and at least a portion of the body unit. The compression unit circumferentially surrounds the mounting structure, at least portions of the soft cannula, and at least portions of the body unit. Further, the compression unit of the injection molding is cooled, thereby providing an internal material tension of the compression unit. Cooling typically requires contraction of the compression unit. In addition, the mold core pin is removed. It is understood by those skilled in the art that the molded core pin may be removed immediately after injection molding of the compression unit (i.e., prior to cooling of the compression unit), after cooling of the compression unit, or even during cooling of the compression unit.

Optionally, the body unit is also produced by injection moulding. For example, the body unit may be provided by injection moulding onto a moulded core pin. However, the body unit may also be produced by another suitable method. In particular, if the body unit is produced by injection moulding, the two injection moulding steps may be carried out as two separate injection moulding steps.

The use of injection moulding techniques for manufacturing the compression unit and optionally the body unit has the advantage that only a reduced number of tools is required. Furthermore, no additional connecting steps, such as welding or gluing, are required. In addition, when the compression unit is injection molded over the body unit and cannula and subsequently cooled, the shrinkage causes internal material tension, which significantly increases the fixation of the soft cannula within the cannula system. If cooling is performed in the mould, the shrinkage and thus the associated internal material tension will increase. Furthermore, an advantage of both the injection moulding body unit and the compression unit is that these two parts must complement each other and thus the number of material defect parts is significantly reduced.

It should be understood that the term "circumferential" does not necessarily require that the mounting structure, cannula and/or body unit have a circular cross-section and/or a cylindrical shape. These components may, independently of each other, comprise a circular, elliptical or angular cross-section and further have any shape suitable for an infusion set.

In some embodiments, the compression unit is injection molded such that it circumferentially surrounds at least 1/3, preferably 1/2, of the outer surface of the body unit, thereby providing a particularly tight and secure connection between the body unit and the compression unit.

In a further embodiment, only the distal end region of the soft cannula is mounted on the mounting structure of the body unit. The compression unit preferably circumferentially surrounds only the distal end region of the soft cannula. As understood by the skilled person, the distal end region faces away from the patient in the operational state. Thus, the distal end region is closer to the body unit than the proximal end region. Thus, upon insertion into the tissue of a patient, the proximal end region is inserted into the tissue first.

In other embodiments, the distal end region is provided with a locking structure for establishing a positive lock (shape closure) and/or an adhesive bond between the soft cannula, in particular the distal end region, and the compression unit. A locking structure establishing a form-locking is advantageous in that during injection moulding of the compression unit onto the soft cannula, material is provided in and/or around the locking structure, thereby providing an improved cannula system wherein the cannula is tightly secured to avoid separation of the cannula from the compression unit and the body unit when the cannula system is removed from the skin. The improved cannula system improves the sealing performance of the cannula system, thereby avoiding the occurrence of infusion leakage.

In a further embodiment, a locking structure is created at the distal end region of the soft cannula before the soft cannula is fitted into the mounting structure of the body unit. The locking structure may be adhered to the distal end region, or a through hole may be created by drilling. Alternatively, a protruding locking structure (e.g. nipple) may be adhered or welded to the distal end region of the soft cannula.

In some embodiments, the locking structure comprises at least one protrusion protruding from the distal end region. For example, the locking structure may be a collar extending from a distal end region of the soft cannula. Preferably, the collar is arranged at the most distal part of the distal end region, i.e. the collar may be a flange. The protrusions may also be teats, hooks or barbs. Additionally, or alternatively, the locking structure may be at least one aperture. Preferably, the hole is a through hole or a blind hole.

In a further embodiment, the distal end region of the soft cannula has a larger diameter than the remainder of the cannula prior to mounting the cannula on the mounting structure. Thus, the cannula does not or only slightly laterally expand when pushed through the mounting structure, which will result in no or less material creep and possibly less leakage.

In a further embodiment, the internal material tension of the compression unit applies a radially inwardly directed compression force. Such a force is particularly advantageous as the risk of leakage between the cannula and the mounting structure and/or between the cannula and the compression unit is further reduced.

In some embodiments, the inner material of the compression unit tensions portions of the soft cannula mounted on the mounting structure. In such an embodiment, at least a portion of the cannula circumferentially surrounded by the compressed unit, preferably the distal end region, is compressed. Thus, the wall thickness of the part of the cannula is smaller than the wall thickness of the remaining part of the cannula that is circumferentially surrounded by the uncompressed unit.

In a further embodiment, the body unit and the compression unit and/or the compression unit and the soft cannula form an adhesive connection during injection molding of the compression unit.

In some embodiments, the method may typically include two separate injection molding steps, thereby reducing the number of manufacturing steps required and the overall production time and cost even further.

According to a second aspect of the invention, the general object is achieved by an intubation system comprising a soft cannula and an intubation unit for holding the soft cannula. The cannula unit comprises a compression unit and a body unit or alternatively may comprise a compression unit and a body unit, wherein the body unit comprises a mounting structure and a cavity for holding the septum. The soft cannula is mounted on a mounting structure of the body unit. Further, the compression unit circumferentially surrounds the mounting structure and circumferentially surrounds at least portions of the body unit. The compression unit further comprises an internal material tension for exerting a compressive force on the soft cannula and the mounting structure.

For example, such cannula systems may be manufactured by the methods as described herein. Furthermore, the body unit and/or the compression unit are typically injection molded.

In some embodiments, the mounting structure may be a protrusion, in particular a cylindrical protrusion or a cubic protrusion.

In a further embodiment, only the distal end region of the soft cannula is attached to the mounting structure, and the compression unit circumferentially surrounds the distal end region of the soft cannula.

In some embodiments, the distal end region of the soft cannula includes a locking structure that provides a positive lock and/or an adhesive bond between the soft cannula and the compression unit. The form-locking and/or adhesive bonding between the soft cannula and the compression unit provides a tight fit of the compression unit and the soft cannula, which avoids the occurrence of leakage. The locking structure for establishing a positive lock (form closure) between the soft cannula and the compression unit may be a protruding locking structure or a recessed locking structure. Adhesive bonding may be provided, for example, by attaching an external adhesive (e.g., glue). Such a cannula system of the invention provides an improved cannula system wherein the cannula is tightly fixed to ensure that separation of the cannula from the compression unit and the body unit is avoided when the cannula system is removed from the skin. The improved cannula system also improves the sealing of the cannula system, thereby avoiding the occurrence of leakage of the infusion fluid.

In a further embodiment, the locking structure comprises at least one protrusion protruding from the distal end region. For example, the locking structure may be a collar extending from a distal end region of the soft cannula. Preferably, the collar is arranged at the most distal part of the distal end region, i.e. the collar may be a flange. The protrusions may also be teats, hooks or barbs. Additionally, or alternatively, the locking structure may be at least one recessed locking structure, such as a hole. Preferably, the hole is a through hole or a blind hole. The locking structure may also be formed by the wall of the soft cannula, in particular by a wavy or stepped wall.

In some embodiments, the distal end region of the soft cannula has a larger diameter than the remainder of the soft cannula. Thus, in these embodiments, the entire distal region has a larger diameter than the remainder of the soft cannula.

Typically, the distal end region of the soft cannula is free of internal material tension.

In some embodiments, the wall thickness of the distal end region of the soft cannula is less than the wall thickness of the rest of the soft cannula.

In other embodiments, the compression unit compresses at least the distal end region of the soft cannula. In these embodiments, a specific fluid-tight system is achieved and the risk of leakage is reduced.

In a further embodiment, the body unit and the compression unit are connected by an adhesive connection and/or the soft cannula and the compression unit are connected by an adhesive connection.

It will be appreciated that such an adhesive connection is typically formed only by the body unit, the compression unit and/or the soft cannula itself. Thus, no external adhesive (e.g. glue) is required nor present, except for the embodiment where an adhesive bond (e.g. by glue) is provided between the soft cannula and the compression unit.

In some embodiments, the cannula system does not comprise additional connecting means, in particular shaped locking means, such as barbs, teats, snap fittings or the like, for coupling and/or connecting the compression unit and the body unit. The cannula system may also not comprise any additional housing parts or fittings which are not an integral part of the cannula unit and/or the soft cannula and/or the body unit. Thus, a preferred cannula system may comprise a soft cannula which is held in place only by the body unit and the compression unit, and therefore not by additional components which are not integral with the body unit or the compression unit. Thereby reducing the rejection rate and the production workload and cost.

In a further embodiment, the body unit may comprise a septum within a cavity for holding the septum. The diaphragm may be fixed by crimping. Such a septum is typically continuously closed, i.e., without a slit, prior to insertion of the needle. In particular, such a septum may not include a slit that is elongated in both the lateral and vertical puncture directions of the septum.

According to another aspect of the invention, the general object is achieved by using a cannula system according to any of the embodiments described herein in an infusion set.

Drawings

Figure 1 shows a cross-sectional view of an intubation system according to an embodiment of the present invention.

Fig. 2a to 2c schematically show a method of manufacturing a cannula system according to an embodiment of the invention.

Figure 3 shows a cross-sectional view of an intubation system according to another embodiment of the present invention.

Figure 4 shows a cross-sectional view of an intubation system according to another embodiment of the present invention.

Detailed Description

Fig. 1 shows an advantageous embodiment of an intubation system 1 according to the invention. The cannula system 1 comprises a soft cannula 10 and a cannula unit for holding the soft cannula 10. The cannula unit comprises a compression unit 20 and a body unit 30. The body unit 30 further comprises a mounting structure 31 and a cavity 32 for receiving the diaphragm. The distal portion 11 of the soft cannula 10 is mounted on the mounting structure 31. The distal end region 11 of the soft cannula 10 has a larger diameter than the rest of the soft cannula. The compression unit 20 circumferentially surrounds the distal end region 11 of the soft cannula 10, the mounting structure 31 and additional portions of the body unit 30. As shown in fig. 1, the compression unit 20 circumferentially surrounds the body unit outer surface greater than 1/3.

As indicated by the arrows, the compression unit 20 has an internal material tension, exerting a radially inward compressive force on the distal end region of the soft cannula and the mounting structure. Thus, a particularly tight connection between the soft cannula 10, the mounting structure 31 and the compression unit 20 is achieved. Furthermore, as can be easily seen from fig. 1, the wall thickness of the distal end region 11 of the soft cannula 10 is smaller than the wall thickness of the rest of the soft cannula 10. Furthermore, as indicated by the arrows, the distal end region 11 of the soft cannula 10 is compressed by the compression force exerted by the compression unit 20. The compression unit 20 and the body unit 30 are connected by an adhesive connection at their contact areas. Thus, a reliable and seal-tight connection is established.

Fig. 2a to 2c depict certain steps of a method of manufacturing an intubation system according to an advantageous embodiment of the invention. As shown in fig. 2a, the body unit 30 with the mounting structure 31 is injection molded onto a mold core pin 40 (mold not shown). In a next step, the distal end region 11 of the soft cannula 10 is mounted on the mounting structure 31 (fig. 2 b). The compression unit 20 is then injection molded over the distal end region of the soft cannula, over the mounting structure and over the other parts of the body unit 30 (fig. 2c, mold not shown). Since the compression unit is at least partially injection moulded on the body unit 30, any production inaccuracies of the proximal side of the body unit are less relevant, as the compression unit must be complementary to those of the body unit 30. Once the compression unit has been injection molded, the molded core pin 40 may be removed and the compression unit cooled, establishing internal material tension thereon, exerting a force on the distal end region 11 of the soft cannula 10 and the mounting structure 31. Generally, cooling may be performed in the mold and/or cooling may be achieved by active cooling. Thus, the compression unit is not allowed to cool to room temperature by itself, but is actively cooled, in particular by using a cooling medium. This rapid cooling enhances the internal material tension. The two-step injection molding sequence can be performed significantly faster than the methods of manufacturing cannula units known in the prior art.

Fig. 3 shows another advantageous embodiment of the cannula system 1 according to the invention. The cannula system 1 comprises a soft cannula 10 and a cannula unit comprising a compression unit 20 and a body unit 30. The body unit 30 comprises a mounting structure 31, the distal end region 11 of the soft cannula 10 being mounted on the mounting structure 31. In the particular embodiment shown, the distal end region 11 comprises two holes 12a as locking structures, which are provided as through holes. The size of the holes 12a is drawn in an enlarged manner for illustrative purposes only. Although the arrows indicating the compression force are not shown in fig. 3 (see fig. 1), also in this embodiment with the hole 12a, the compression unit exerts a compression force on the soft cannula 10. It can be seen that portions of the compression unit 20 enter the bore 12a during injection. After the compression unit cools, a tighter seal between the compression unit 20 and the soft cannula 10 is achieved. In addition, the fixation of the soft cannula 10 within the thin cannula system is improved.

Fig. 4 depicts another embodiment of an intubation system 1 having a soft intubation tube 10 and an intubation unit including a compression unit 20 and a body unit 30 having a mounting structure 31. Typically, the mounting structure may be a protrusion of the body unit, such as a teat. The distal end region 11 of the soft cannula 10 comprises a collar 12b as a locking structure establishing a shape lock between the soft cannula 10 and the compression unit 20. The loop 12b is circumferentially arranged at the most distal part of the distal end region 11. During injection molding of the compression unit 20, material is provided around the collar 12 b. As a result, the soft cannula 11 is anchored within the compression unit 20, thereby increasing the fixation of the cannula within the cannula system and the seal between the cannula and the compression unit.

Claims (15)

1. A method for manufacturing a cannula system having a body unit and a compression unit, the method comprising the steps of:

-providing a body unit comprising a mounting structure, the body being mounted onto a moulding core pin, wherein the body unit is optionally provided by injection moulding onto the moulding core pin;

-mounting a soft cannula on the mounting structure of the body unit;

-injection moulding the compression unit over the soft cannula and over at least portions of the body unit, wherein the compression unit circumferentially surrounds the mounting structure, at least portions of the soft cannula and at least portions of the body unit;

-cooling the compression unit, thereby providing an internal material tension of the compression unit;

-removing the moulding core pin.

2. The method of claim 1, wherein only a distal end region of the soft cannula is fitted over the mounting structure of the body unit, and wherein the compression unit preferably circumferentially surrounds only the distal end region of the soft cannula.

3. The method according to claim 2, wherein the distal end region is provided with a locking structure for establishing a shape lock and/or an adhesive bond between the soft cannula and the compression unit.

4. The method of claim 3, wherein a locking feature is formed at the distal end region of the soft cannula prior to mounting the soft cannula on the mounting feature of the body unit.

5. The method according to any one of claims 3 or 4, wherein the locking structure comprises at least one protrusion and/or at least one hole protruding from the distal end region, the protrusion preferably being a collar arranged at the most distal part of the distal end region, the hole preferably being a through hole or a blind hole.

6. The method of any of claims 2-5, wherein the distal end region of the soft cannula has a larger diameter than the remainder of the cannula prior to fitting the cannula on the mounting structure.

7. The method according to any of the preceding claims, wherein the inner material tension of the compression unit applies a radially inwardly directed compression force and/or wherein the inner material tension of the compression unit compresses the soft cannula.

8. The method according to any of the preceding claims, wherein the body unit and the compression unit and/or wherein the compression unit and the soft cannula form an adhesive connection during injection molding of the compression unit.

9. An intubation system (1) comprising a soft intubation tube (10) and an intubation unit for holding the soft intubation tube (10), wherein the intubation unit comprises a compression unit (20) and a body unit (30), wherein the body unit (30) comprises a mounting structure (31) and a cavity (32) for holding a septum, wherein the soft intubation tube (10) is mounted on the mounting structure (31), wherein the compression unit (20) circumferentially surrounds the mounting structure (31) and at least parts of the body unit (30), and wherein the compression unit (20) comprises an internal material tension for exerting a compression force on the soft intubation tube (10) and the mounting structure (31).

10. An cannula system (1) according to claim 9, wherein only a distal end region (11) of the soft cannula (10) is fitted on the mounting structure (31), and wherein the compression unit (20) circumferentially surrounds the distal end region (11) of the soft cannula (10).

11. The cannula system (1) according to claim 10, wherein the distal end region (11) of the soft cannula comprises a locking structure providing a shape lock and/or an adhesive bond between the soft cannula (10) and the compression unit (20).

12. An intubation system according to claim 10 or 11, wherein the locking structure comprises at least one protrusion, preferably a collar (12b) arranged at the most distal part of the distal end region (11), and/or at least one hole (12a), preferably a through hole or a blind hole, protruding from the distal end region (11).

13. An intubation system (1) according to any one of claims 10 to 12, wherein a distal end region (11) of the soft intubation tube (10) has a larger diameter than the rest of the soft intubation tube (10).

14. An cannula system (1) according to any of the claims 10 or 13, wherein the compression unit (20) compresses at least the distal end region (11) of the soft cannula (10), and/or wherein the body unit (30) and the compression unit (20) are connected by an adhesive connection, and/or wherein the soft cannula (10) and the compression unit (20) are connected by an adhesive connection.

15. Use of a cannula system according to any of claims 9-14 in an infusion set.