Abstract
Disclosed herein is a pierceable elastic septum for use in drug reservoirs and infusion sets, the pierceable septum comprising a first surface and a second surface. The first surface and the second surface are positioned opposite to each other. A distance between the first surface and the second surface is not constant over the first surface, and is configured such that if a higher pressure is applied to the first surface as compared to the second surface, a component of a force, which is exerted on the first surface, acts towards an axis (A) which intersects the center of the first surface and the center of the second surface.
Claims
1. A pierceable elastic septum for use in drug reservoirs and infusion sets, comprising: first and second surfaces positioned opposite to each other, wherein the first surface comprises a circumferentially closed groove surrounding the center of the first surface; a varying distance between the first surface and the second surface configured such that when a higher pressure is applied to the first surface than the second surface, a component of a force exerted on the first surface acts towards an axis (A) which intersects the center of the first surface and the center of the second surface.
2. The pierceable septum according to claim 1, wherein the closed groove is circular.
3. The pierceable septum according to claim 1, wherein the groove is symmetrically arranged with respect to a rotational axis of the septum.
4. The pierceable septum according to claim 1, wherein the groove has a cross-section selected from the group consisting of angular, rectangular, quadratic and triangular.
5. The pierceable septum according to claim 1, wherein the varying distance between the first surface and the second surface is greater at the center of the first surface than at a different position of the first surface.
6. The pierceable septum according to claim 1, wherein the septum is prestressed by radial compression.
7. The pierceable septum according to claim 1, wherein a plurality of blind holes surrounds the center of the first surface.
8. The pierceable septum according to claim 7 wherein the plurality of blind holes surrounds the center of the first surface in a circular manner.
9. The pierceable septum according to claim 1, wherein the first surface is conical or hemispherical, wherein the thickness (T) of the septum declines from the center to an edge.
10. The pierceable septum according to claim 1, wherein the first surface comprises a protruding part of an elliptic paraboloid and wherein the center of the first surface defines the vertex of the elliptic paraboloid.
11. The pierceable septum according to claim 10, wherein the septum is shaped such that an area of the first surface between the edge and the center of the first surface exists, at which the distance between the first surface and the second surface is smaller than the distance between the first surface and the second surface at both the edge and at the center of the first surface.
12. The pierceable septum according to claim 11, wherein the distance between the first surface and the second surface is essentially at the full area of the first surface between the edge and the center of the first surface smaller than the distance between the first surface and the second surface at the edge and at the center of the first surface.
13. The pierceable septum according to claim 1, wherein the first surface is at least partially wavelike in cross-section.
14. The pierceable septum according to claim 1, wherein the septum is symmetrical with respect to at least one mirror plane (P), wherein the mirror plane (P) is transverse or perpendicular to the axis (A) which intersects the center of the first surface and the center of the second surface.
15. The pierceable septum according to claim 1, wherein: the septum comprises a first outer layer having the first surface as an outer surface, a second outer layer having the second surface as an outer surface, and middle layer sandwiched between the first and second outer layers; and the hardness and/or the elastic modulus of the middle layer is different from the hardness and/or the elastic modulus of the first and second outer layers.
16. The pierceable septum of claim 15, wherein the hardness and/or the elastic modulus of the middle layer is smaller than the hardness and/or the elastic modulus of the first and second outer layers.
17. An infusion set comprising a septum according to claim 1.
18. The infusion set according to claim 17, wherein the septum is prestressed by radial compression.
19. A reservoir for a liquid drug comprising a septum according to claim 1.
20. The reservoir according to claim 19, wherein the septum is prestressed by radial compression.
21. A method of using a pierceable septum, comprising: (a) providing a septum having first and second surfaces positioned opposite to each other, the first surface having a circumferential groove; (b) piercing the septum with a cannula needle in a location near the center of the septum; (c) applying fluid pressure to the first surface, the fluid pressure generating (i) a first force F.sub.1 directed from the groove toward a center axis (A) of the septum, thereby compressing the septum in a center location near the cannula needle; and (ii) a force F.sub.3 directed from the groove outwardly toward a periphery of the septum, whereby an edge of the septum at the periphery compresses against a housing in which the septum is disposed.
22. The method of claim 21, further comprising removing the cannula needle and sealing the septum with application of the force F.sub.1.
23. The method of claim 21, further comprising applying a force F.sub.2 from the housing toward the axis (A) to thereby enhance the seal between the housing and the periphery of the septum.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0043] FIG. 1 (a) shows a cross-sectional view of a pierceable septum in accordance to one embodiment of this disclosure;
[0044] FIG. 1 (b) shows a plan view of a first surface of a pierceable septum in accordance to one embodiment of this disclosure;
[0045] FIG. 1 (c) shows a plan view of a first surface of a pierceable septum in accordance to another embodiment of this disclosure;
[0046] FIG. 2 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0047] FIG. 3 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0048] FIG. 4 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0049] FIG. 5 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0050] FIG. 6 shows a plan view of a first surface of a pierceable septum in accordance to another embodiment of this disclosure;
[0051] FIG. 7 shows a cross-sectional view of a pierceable septum in accordance to one embodiment of this disclosure;
[0052] FIG. 8 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0053] FIG. 9 shows a cross-sectional view of a pierceable septum in accordance to another embodiment of this disclosure;
[0054] FIG. 10 (a) shows a cross-sectional view of a pierceable septum built into a housing in accordance to another embodiment of this disclosure;
[0055] FIG. 10 (b) shows a cross-sectional view of a pierceable septum built into a housing in accordance to another embodiment of this disclosure;
[0056] FIG. 11 shows a cross-sectional view of a reservoir for drugs comprising a septum in accordance to another embodiment of this disclosure;
[0057] FIG. 12 (a) shows a cross-sectional view of a pierceable septum built into a housing in accordance to another embodiment of this disclosure;
[0058] FIG. 12 (b) shows a cross-sectional view of a pierceable septum built into a housing in accordance to another embodiment of this disclosure; and
[0059] FIG. 13 shows a cross-sectional view of a reservoir for drugs comprising a septum in accordance to another embodiment of this disclosure.
DESCRIPTION
[0060] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.
[0061] An advantageous embodiment of a pierceable septum 1 according to this disclosure is shown in FIG. 1 (a). The pierceable septum 1, displayed in a cross-sectional view, comprises a first surface 11 and a second surface 12, which are positioned opposite to each other. As exemplified by distances D.sub.1 and D.sub.2, the distance between the first surface and the second surface is not constant over the first surface. The distance between the first surface and the second surface as a function of the diameter (radial distance from axis A) is designed such that if a pressure p.sub.1 is applied to the first surface, which is higher than a pressure p.sub.2 applied to the second surface, a component F.sub.1 of a force, which is exerted on the first surface, acts towards an axis A intersecting the center of the first surface 11 and the center of the second surface 12. In the particular embodiment shown, a component of force F.sub.1 can act transversely, towards axis A. In addition, a component F.sub.3 of a force, which is exerted on the first surface, acts opposite to an axis which intersects the center of the first surface and the center of the second surface. As readily realized by those skilled in the art, the component F.sub.1 is axis-directed and leads to compression of the septum at the center of the first surface 11, while the component F.sub.3 is edge-directed and leads to an expansion of the septum at the edges of the first surface 11.
[0062] In the embodiment of FIG. 1 (a), the first surface 11 comprises a groove 13 having a rectangular cross-section, which circumferentially surrounds the center of the first surface 11. FIG. 1 (b) represents a plan view of the first surface 11 comprising a groove 13, which circumferentially surrounds the center of the first surface 11 in a circular manner and which is symmetrically arranged with respect to a rotational axis. FIG. 1 (c), displays another embodiment of this disclosure as a plan view of the first surface 11. Therein, the first surface 11 of the pierceable septum 1 comprises two grooves 13a and 13b surrounding the center of the first surface in a half-circular manner, without merging into each other. In this particular embodiment, the two grooves are symmetrically arranged with respect to a rotational axis. However, the grooves could also be arranged in an asymmetrical manner. In both the embodiments of FIG. 1 (a, b) and FIG. 1 (c), the first surface 11 is stepped with the distance between the first surface 11 and the second surface 12 being either D.sub.1 or D.sub.2 for each point.
[0063] FIG. 2 shows another embodiment of a pierceable septum 1 according to this disclosure. As can be seen from the cross-sectional view of septum 1, the first surface 11 comprises a circumferential groove 13 which has a triangular cross-section. Moreover, the shape of the first surface of the septum is shaped in such a way, that the distance D.sub.1 between the first surface 11 and the second surface 12 at the center of the first surface is larger than a distance D.sub.2 between the first surface and the second surface at a different position of the first surface. Here, the distance between the first surface 11 and the second surface 12 varies continuously from D.sub.1 at the edges to D.sub.2 at the center of the groove 13. Groove 13 has a depth D.sub.3 and a width w.
[0064] FIG. 3 shows another embodiment of a pierceable septum 1 according to this disclosure, wherein the first surface comprises a circumferential groove 13 which has a curved cross-section, also resulting in a continuous change in the distance between first surface 11 and the second surface 12.
[0065] The septum shown in FIG. 4 represents another advantageous embodiment of this disclosure. Therein, the first surface 11, positioned opposite to second surface 12, is conical. The thickness T of the septum declines from the center of the first surface to an edge.
[0066] The septum shown in FIG. 5 represents another embodiment of this disclosure. Therein, the first surface 11, which is positioned opposite to the second surface 12 is hemispherical. As in case of FIG. 4, the thickness T declines from the center of the first surface to an edge.
[0067] FIG. 6 shows a top view of the first surface 11 of another embodiment of a pierceable septum 1. The first surface 11 comprises a plurality of blind holes 14, which surrounds the center of the first surface in a circular manner.
[0068] Another advantageous embodiment of a pierceable septum 1 according to this disclosure is shown in FIG. 7. The pierceable septum 1, displayed in cross-sectional view, comprises a first surface 11 and a second surface 12, which are positioned opposite to each other. As exemplified by distance D.sub.1 and D.sub.2, the distance between the first surface 11 and the second surface 12 is not constant over the first surface 11. The distance between the first surface 11 and the second surface 12 as a function of the diameter (radial distance from axis A) is designed such that if a pressure p.sub.1 is applied to the first surface, which is higher than a pressure p.sub.2 applied to the second surface, a component F.sub.1 of a force which is exerted on the first surface acts towards an axis A intersecting the center of the first surface 11 and the center of the second surface 12. In addition, a component F.sub.3 of a force which is exerted on the first surface acts opposite to an axis which intersects the center of the first surface and the center of the second surface, i.e., a component F.sub.3 can act away from an axis which intersects the center of the first surface and the center of the second surface. As readily realized by those skilled in the art, the component F.sub.1 is axis-directed and leads to compression of the septum at the center of the first surface 11, while the component F.sub.3 is edge-directed and leads to an expansion of the septum at the edge of the first surface 11. In the embodiment shown, the first surface 11 comprises a protruding part 15 of an elliptic paraboloid. As readily seen, the center of the first surface defines the vertex of the paraboloid. Furthermore, as indicated by distance D.sub.2, the pierceable septum shown is shaped in such a way that an area exists at which the distance between the first surface 11 and the second surface 12 is smaller than the distance between the first surface 11 and the second surface 12 at the edge (see D.sub.3) and at the center of the first surface (see D.sub.1). In this particular embodiment, the distance between the first surface 11 and the second surface 12 is at the full area of the first surface between the edge and the center of the first surface 11 smaller than the distance between the first surface 11 and the second surface 12 at the edge and at the center of the first surface 11. It can be further seen from FIG. 7, that the first surface 11 of the pierceable septum may comprise a circumferentially closed groove with a curved cross section and the first surface 11 is at least partially wavelike in cross-section.
[0069] FIG. 8 shows another embodiment of a pierceable septum 1 according to this disclosure, wherein the septum is symmetrical with respect to mirror plane P. The mirror plane P is perpendicular to axis A. The axis A intersects the center of the first surface 11 and the center of the second surface 12. As a consequence of the symmetrical configuration, the first surface 11 and the second surface 12 each comprise a protruding part 15 of an elliptic paraboloid and are equally shaped.
[0070] FIG. 9 shows another embodiment of a pierceable septum 1 according to this disclosure. The septum 1 comprises three layers, first outer layer 16, middle layer 17 and second outer layer 18. The first outer layer 16 comprises the first surface 11 as an outer surface and the second outer layer 18 comprises the second surface 12 as an outer surface. As can be seen, the middle layer 17 is sandwiched between the first outer layer 16 and the second outer layer 18. In this particular septum shown, the contact surfaces of the three layers are plane-parallel and transversal to the axis which intersect the center of the first surface 11 and the center of the second surface 12. Such design with a middle layer 17 is not limited to a particular embodiment of the septum 1 but may also be used in the context of other embodiments, such as an embodiment according to FIG. 7.
[0071] FIG. 10 (a) depicts a pierceable septum 1 according to this disclosure, which is built into a housing unit 20. The housing unit 20 is part of a cannula unit 25, which can be part of an infusion set. Additionally, cannula unit 25 may comprise a flexible infusion cannula 23 which can be inserted into the patient's tissue by insertion of a piercing needle through the septum, prior to assembly of removable connector device 24. As can be readily seen, the housing unit 20 and the septum form a compartment 22, which can comprise a liquid drug. For example, the drug can be pumped under pressure into compartment 22 by an infusion pump (not shown) which is in fluid connection with connector cannula 21. Connector cannula 21 is part of connector device 24, which is removably connected to cannula unit 25 and not depicted in greater detail. In this particular embodiment, a force F.sub.1 might emanate from a fluid pressure p.sub.1 within compartment 11. As indicated by the arrows, an axis-directed component F.sub.1 of the force applied to the first surface acts towards an axis (not shown in FIG. 10 (a), see FIG. 1 (a)) which intersects the center of the first surface and the center of the second surface. As a result, the septum 1 is compressed at the center of the first surface and engages connector cannula 21. In addition, an edge-directed component F.sub.3 of a force, which is exerted on the first surface, acts opposite to an axis which intersects the center of the first surface and the center of the second surface, thereby ensuring sealing engagement between the housing 20 and the peripheral edge of first surface 11. Additionally, as indicated by the arrows the pierceable septum 1 is exposed to a force F.sub.2, by being prestressed by radial compression. Advantageously, the piercing of septum 1 does not lead to any leakage occurring between the walls of the cannula or the needle, because a component F.sub.1 of a force acts towards the connector cannula and also towards an axis, which intersects the center of the first surface and the center of the second surface. In addition, while a second force F.sub.2 acts toward the same axis, a third force F.sub.3 acts opposite to this axis, which results in a particular tight sealing between housing 20 and septum 1.
[0072] FIG. 10 (b) depicts cannula unit 25 with pierceable septum 1, built into housing unit 20. However the connector device (see 24 in FIG. 10(a)) comprising a connector cannula (see 21 in FIG. 10(a)) has been removed and thus disconnected from the cannula unit 25. As indicated by curved line 26, the removal of the connector cannula led to the formation of a through-cut or a puncture in the septum. This through-cut or puncture is now sealingly closed, as firstly a component F.sub.1 of a force acts towards an axis, which intersects the center of the first surface and the center of the second surface and secondly as a second force F.sub.2 acts toward the same axis.
[0073] FIG. 11 shows a reservoir for drugs 30, for example an insulin cartridge comprising a walls 31 and liquid drug 32. A pierceable septum 1 according to this disclosure allows to withdraw drug 32 from the reservoir by a cannula and ensures tight sealing of the pierced septum 1 after removal of the cannula. The particular septum shown in FIG. 11 comprises second surface 12 and first surface 11 with a circumferential groove.
[0074] FIG. 12 (a) depicts a pierceable septum 1 according to this disclosure, which is built into a housing unit 20. The housing unit 20 is part of a cannula unit 25, which can be part of an infusion set. Additionally, cannula unit 25 may comprise a flexible infusion cannula 23 which can be inserted into the patient's tissue by insertion of a piercing needle through the septum, prior to assembly of removable connector device 24. As can be readily seen, the housing unit 20 and the septum form a compartment 22, which can comprise a liquid drug. For example, the drug can be pumped under pressure into compartment 22 by an infusion pump (not shown) which is in fluid connection with connector cannula 21. Connector cannula 21 is part of connector device 24, which is removably connected to cannula unit 25 and not depicted in greater detail. In this particular embodiment, a force might emanate from a fluid pressure p.sub.1 within compartment 22. As indicated by the arrows, an axis-directed component F.sub.1 of the force applied to the first surface acts towards an axis (not shown in FIG. 12 (a), see FIG. 7) which intersects the center of the first surface and the center of the second surface. As a result, the septum 1 is compressed at the center of the first surface and engages connector cannula 21. In addition, an edge-directed component F.sub.3 of a force, which is exerted on the first surface, acts opposite to an axis which intersects the center of the first surface and the center of the second surface, thereby ensuring sealing engagement between the housing 20 and the peripheral edge of first surface 11. Additionally, as indicated by the arrows, the pierceable septum 1 is exposed to a force F.sub.2, by being prestressed by radial compression. Advantageously, the piercing of septum 1 does not lead to any leakage occurring between the walls of the cannula or the needle, because a component F.sub.1 of a force acts towards the connector cannula and also towards an axis, which intersects the center of the first surface and the center of the second surface. In addition, while a second force F.sub.2 acts toward the same axis, a third force F.sub.3 acts opposite to this axis, which results in a particular tight sealing between housing 20 and septum 1.
[0075] FIG. 12 (b) depicts cannula unit 25 with pierceable septum 1, built into housing unit 20. However the connector device (see 24 in FIG. 4(a)) comprising a connector cannula (see 21 in FIG. 12 (a)) has been removed and thus disconnected from the cannula unit 25. As indicated by curved line 26, the removal of the connector cannula led to the formation of a through-cut or a puncture in the septum. This through-cut or puncture is now sealingly closed, as firstly a component F.sub.1 of a force acts towards an axis, which intersects the center of the first surface and the center of the second surface and secondly as a second force F.sub.2 acts toward the same axis.
[0076] FIG. 13 shows a reservoir for drugs 30, for example an insulin cartridge comprising walls 31 and liquid drug 32. A pierceable septum 1 according to this disclosure allows to withdraw drug 32 from the reservoir by a cannula and ensures tight sealing of the pierced septum 1 after removal of the cannula. The particular septum shown in FIG. 13 comprises second surface 12 and first surface 11 with a protruding part of an elliptic paraboloid 15.
[0077] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
