EP4637901A1

EP4637901A1 - Sealing element with shape memory alloy

Info

Publication number: EP4637901A1
Application number: EP23818023.6A
Authority: EP
Inventors: Robert Litschko
Original assignee: Biotronik AG
Current assignee: Biotronik AG
Priority date: 2022-12-22
Filing date: 2023-12-05
Publication date: 2025-10-29
Also published as: WO2024132483A1; CN120282813A

Abstract

A sealing device (1) for a medical device, the sealing device (1) comprising: an annular outer support member (2) with inner surface (2a), a deformable annular sealing member (3) comprising an outer surface (3a), the a support member (2) arranged over the sealing member (3) so that the inner surface (2a) of the annular outer support member (2) faces the outer surface (3a) of the deformable annular sealing member (3), and a body (4) of a shape memory alloy, the body surrounded by the deformable annular sealing member (3), wherein the body (4) extends along an axial direction (x) and is configured to assume an expanded state at a first temperature and a contracted state at a higher second temperature, wherein the body (4) is contracted in the axial direction (x) in the contracted state causing the deformable annular sealing member (3) to expand in a radial direction (R).

Description

Sealing element with shape memory alloy

The present invention relates to a sealing device, preferably for a medical device, a medical device, and a method for sealing a medical device using a sealing device according to the present invention.

In medical devices, it is often desirable to be able to detachably connect to components of a medical device to one another so that a sealed connection is formed between the two components.

For instance, it would be desirable to provide such a detachable sealed connection between a balloon and a catheter, to provide a balloon catheter with replaceable balloon, thus offering the possibility to combine different balloons and catheters.

To date there are no known solutions for detachably sealing balloons on catheters. In general, screw connections, for example, are used for detachable connections between components of a medical device.

Often, the detachability of known solutions is not based on the difference between physiological and non-physiological conditions, so that it cannot be safely ruled out that connections may detach again under physiological conditions, e.g. by the action of mechanical forces suitable for this purpose, and thus lead to a patient risk.

Based on the above, the problem to be solved by the present invention is to provide an improved sealing device, medical device, and method for sealing a medical device using a sealing device according to the present invention, so as to allow a save gas- and liquid-tight sealing connection between two components that is releasable. Preferably, the sealing device shall be able to seal under physiological conditions (e.g. body temperature) and can be released, ideally without tools, under non-physiological conditions (e.g. under a lower temperature than body temperature). Furthermore, it is desirable in particular to provide a sealing device having a soft surface so that no damage can occur to sensitive mating parts.

This problem is solved by a sealing device having the features of claim 1, a medical device having the features of claim 11, and a method having the features of claim 15.

According to claim 1, a sealing device is disclosed, comprising:

- an (annular) outer support member comprising an inner surface,

- a deformable (annular) sealing member comprising an outer surface, the outer support member being configured to be arranged over the (annular) sealing member so that the inner surface of the (annular) outer support member faces the outer surface of the (annular) sealing member, and

- a body formed out of a shape memory alloy, wherein the body is embedded in the (annular) sealing member, wherein the body extends along an axial direction and is configured to assume an expanded state at a first temperature and a contracted state at a higher second temperature, wherein the body is contracted in the axial direction in said contracted state causing the deformable (annular) sealing member to expand in a radial direction, particularly such that the outer surface of the sealing member moves towards the inner surface of the (annular) outer support member when the latter is arranged over the (annular) sealing member, thus allowing to clamp a circumferential portion of a component in a sealing fashion between the inner and outer surface.

The higher second temperature enables a contraction of the body and thus a clamping an/or sealing is possible whereas this is not possible at the first lower temperature.

The present invention may enable a balloon to be changed on a catheter in a clinical setting. Until now, the balloon and catheter have been manufactured as a single unit, which meant that a great deal of material had to be kept on hand in the clinic. With the present invention it is possible, for example, to have a universal catheter on which balloons of different lengths and diameters can be installed using the sealing device according to the present invention, e.g., by sealingly clamping each end section of a balloon between the outer surface of the (annular) sealing member and the inner surface of the (annular) outer support member. The latter can already be provided on the respective end section of the balloon, i.e. can be an integral part of the balloon. This allows one to use the catheter several times by cleaning and sterilizing it after the operation. This also allows more expensive materials to be used in the manufacture of the catheter. At the same time, the amount of waste is reduced.

Of course, the present invention can also be applied in other fields than balloons/catheters where it is important to achieve an undetachable seal under physiological conditions, but which can be easily released (preferably without tools) under non-physiological conditions (e.g. for clamping components).

According to an embodiment of the invention, the body is a (annular) structure surrounding an interior space in a circumferential direction that is orthogonal to the axial direction, and having an inside facing said interior space, and having an outside facing away from the inside.

According to another embodiment of the invention, the deformable (annular) sealing member comprises an inner portion arranged on the inside of the body, and an outer portion arranged on the outside of the body, particularly so as to cover the body from all sides.

Furthermore, according to another embodiment of the invention, the deformable (annular) sealing member may surround a through-opening of the sealing device. The through-opening is configured for receiving a component, particularly a component of a medical device, wherein particularly said component is a shaft of a catheter.

The deformable (annular) sealing member, particularly its inner portion, may comprise an inner surface.

In another embodiment of the present invention, the sealing device may comprise an (annular) inner support member, wherein the inner surface of the deformable (annular) sealing member is bonded to the (annular) inner support member. The (annular) inner support member may define said through-opening and is configured to be bonded to said component received in said through-opening.

In a further embodiment the (annular) inner support member may not have a through- opening. Instead the (annular) inner support member may have a recess for receiving a component, particularly a component of a medical device, wherein particularly said component is a shaft of a catheter. Such inner support members can be used for sealing an end portion of a device, preferably a distal end of a catheter.

The first temperature may be smaller than 30°C and the second temperature may be larger or equal to 35°C.

Shape memory alloy materials are metal alloys which are able to change their shape and return to their original shape depending on the temperature. This shape change is due to a crystalline phase change. The shape memory alloy material may be selected from nickel titanium alloys, copper aluminum nickel alloys, copper zinc aluminum alloys, iron manganese silicon alloys. A preferred shape memory alloy material may be based on a nominal composition of 50:50 atomic percent nickel titanium.

The deformable (annular) sealing member may be formed out of an elastic material, preferably an elastomer, more preferably a thermoplastic elastomer.

According to a further aspect of the present invention, a medical device is disclosed that comprises at least one sealing device according to the present invention, wherein the medical device comprises a first component having a circumferential end portion configured to be arranged between the outer surface of the deformable (annular) sealing member and the inner surface of the (annular) outer support member.

The medical device may comprise a second component configured to be arranged in the through-opening surrounded by the deformable (annular) sealing member. The medical device may be a balloon catheter, wherein the first component is a balloon of said balloon catheter and the second component preferably is a catheter shaft of the balloon catheter, wherein particularly the catheter shaft comprises a lumen that is configured to communicate with an interior space enclosed by the balloon, e.g., so as to be able to inflate the balloon via said lumen.

Particularly, said circumferential end portion of the balloon delimits an opening via which the catheter shaft is inserted into the balloon to arrange the balloon on the catheter shaft.

A further sealing device according to the present invention can also be used to seal an opposing further circumferential end portion of the balloon that delimits a further opening of the balloon for insertion of the catheter shaft so as to mount the balloon on the catheter shaft. Here, in turn, the further circumferential end portion of the balloon is configured to be arranged between the outer surface of the deformable (annular) sealing member and the inner surface of the (annular) outer support member of the further sealing device.

The catheter shaft is configured to be arranged in the through-opening surrounded by the deformable (annular) sealing member of the further sealing device. The catheter shaft can comprise an outer shaft member and an inner shaft member, the inner shaft member being slidably arranged in a lumen of the outer shaft member, so that the catheter shaft is extendable by pulling the inner shaft member partially out of the outer shaft member.

Here, a distal sealing device according to the present invention is arranged on a distal end portion of the inner shaft member, wherein the (annular) inner support member of this sealing device accommodates the distal end portion of the inner shaft member in its through- opening and is bonded to the inner shaft member.

However, the sealing device according to the present invention may not only be used in medical devices. The sealing device may be used in any other device where a sealing, preferably of a tubular or rod-shaped object e.g. a shaft, is required. The sealing may be used as a thermal shrink-fit collar, a thermal shrink-fit ring or a thermal shrink-fit clamp. The sealing device may be used as a hose clamp or fastener. Furthermore, a proximal sealing device according to the present invention has its through- opening delimited by the inner surface of the deformable (annular) sealing member (i.e. does not comprise an (annular) inner support member). Thus, the deformable (annular) sealing member of the proximal sealing device can reversibly clamp also the inner shaft member when the body is brought into its contracted state by increasing the temperature. Particularly, in order to decrease the risk that the inner shaft member is squeezed by the proximal sealing device in the contracted state of the body of the proximal sealing device, the inner shaft member can comprise a supporting structure, particularly supporting ring. Such a supporting structure/ring can be formed by an X-ray marker of the balloon catheter that is arranged on the inner shaft member.

According to yet a further aspect of the present invention, a method for sealing a medical device using at least one sealing device according to the present invention is disclosed, the method comprising the steps of

- Providing a medical device comprising a first component

- Arranging a circumferential portion of the first component between the inner surface of the (annular) outer support member and the outer surface of the deformable (annular) sealing member, and

- heating the body so that the body assumes its contracted state and thereby causes the deformable (annular) sealing member to expand in the radial direction so that the outer surface of the deformable (annular) sealing member moves towards the inner surface of the (annular) outer support member and sealingly clamps the circumferential portion of the first component between said inner and outer surface.

The method according to the present invention can be further characterized in corresponding embodiments using the embodiments and features described above with respect to the sealing device and medical device according to the present invention. Particularly, said first component is a balloon of a balloon catheter, wherein the circumferential portion of the balloon is preferably a circumferential end portion of the balloon delimiting an opening for the insertion of the catheter shaft of the balloon catheter (see also above). In the following, embodiments of the present invention, as well as further features and advantages of the present invention shall be described with reference to the Figures, wherein

Fig. 1 shows a schematic cross-sectional view of an embodiment of a sealing device according to the present invention,

Fig. 2 shows transforming the sealing member’s body from its expanded state to its contracted state and vice versa,

Fig. 3 shows a medical device, here in form of a balloon catheter using a sealing device according to the present invention in order to mount a balloon onto the catheter in a sealed fashion, and

Fig. 4 shows a medical device comprising an extendable catheter shaft so as to accommodate balloons of different lengths using a sealing device according to the present invention.

Fig. 1 shows in conjunction with Fig. 2 an embodiment of a sealing device 1 according to the present invention. The sealing device 1 is particularly suited for a medical device, such as a balloon catheter 100, but can also be applied in other fields that require detachable sealing means as well.

As indicated in Figs. 1 and 2, the sealing device 1 comprises an annular outer support member 2 comprising an inner surface 2a, an annular deformable sealing member 3 comprising an outer surface 3a, the annular outer support member 2 being configured to be arranged over the annular deformable sealing member 3 so that the inner surface 2a of the annular outer support member 2 faces the outer surface 3 a of the annular deformable sealing member 3. Furthermore, the sealing device 1 comprises a body 4 formed out of a shape memory alloy, wherein the body 4 is encapsulated by the annular deformable sealing member 3, wherein the body 4 extends along an axial direction x and is configured to assume an expanded state at a first temperature and a contracted state at a higher second temperature. The body 4 is contracted in the axial direction x in said contracted state relative to the expanded state causing the annular deformable sealing member 3 to expand in a radial direction R.

The expanded state is shown on the left-hand side of Fig. 2, whereas the contracted state of the body 4 is shown on the right-hand side of Fig. 2. As can be inferred from Fig. 2, due to the body being contracted in the axial direction x, the deformable body 4 is contracted in this direction to and thereby expands radially in the radial direction R. Particularly, the respective radial direction R extends orthogonal to the axial direction x. Thus, the circumference of the annular deformable sealing member 3 is increased in the contracted state. This allows to sealingly clamp a circumferential portion 102 of a component (e.g. of a medical device such as balloon 101) in between the inner and outer surface 3a, 2a.

As indicated in Fig. 2, the clamping can be activated by heating H, i.e. increasing the temperature of the body 4, which causes the shape memory alloy to transition to its contracted state (see right hand side). On the other hand, in case the body 4 is cooled C again, the body 4 returns to its expanded state (see left hand side) causing the sealing device 1 to disengage. If necessary, an additional outer force may be applied for disengaging the sealing device.

The body 4 may have recesses 4a. The recesses 4a may be cut outs in the body 4. Optionally the force transmission from the body 4 made of the shape memory alloy to the deformable sealing member 3 may be enhanced by integrating at least one force transmitting object 7 between the annular deformable sealing member 3 and the body 4. The force transmitting object 7 between the annular deformable sealing member 3 and the body 4 may be positioned at distal and proximal (cutting) edges of the recesses 4a of the body 4. This force transmitting object 7 can either be a separate piece of material or formed by folding over a piece of the tongue that forms when the recess is cut out but not severed at the distal and proximal edges. In the latter case, starting from the body 4, the force transmitting objects 7 protrude either radially outward or radially inward. When inserting a separate piece of material, they can protrude both radially outward and inward. The force transmitting object 7 has an increased area for force transmission compared to the distal and proximal (cutting) edges of the recesses 4a of the body4. On the one hand the at least one object leads to an increase of the force which is directed towards the axial direction x and on the other hand can prevent constriction or indentation of the body 4 made of the shape memory alloy (e.g. NiTi) into the deformable sealing member 3 when the body 4 contracts.

Preferably, the body 4 is an annular structure formed out of the shape memory alloy and surrounds an interior space in a circumferential direction U that is orthogonal to the axial direction x. The body / annular structure 4 comprises an inside 4a facing said interior space, and an outside 4b facing away from the inside 4a. Particularly, the annular deformable sealing member 3 circumferentially surrounds the body 4 and therefore comprises an inner portion 30 arranged on the inside 4a of the body 4, and an outer portion 31 arranged on the outside 4b of the body 4. Moreover, also the face sides of the annular structure 31 can be covered by the annular deformable sealing member 3.

Furthermore, the sealing device 1 comprises a through-opening 6 for accommodating a second component 103 of the device to be sealed such as a catheter shaft 103 (cf. Figs. 3 and 4). Particularly, the annular deformable sealing member 3 of the sealing device comprises a circumferential inner surface 3b. Preferably, an annular inner support member 5 of the sealing device is connected to said inner surface 3b of the annular deformable sealing member 3 and delimits said through-opening 6. Preferably, the annular inner support member 5 is configured to be arranged on the second component 103 and bonded thereto, e.g. by an adhesive.

Fig. 3 shows an application of the sealing device 1 in the framework of a medical device 100, here for example in the form of a balloon catheter 100. The balloon catheter comprises a first component 101 in the form of a balloon 101 having two opposing circumferential end portions 102 each delimiting an opening for receiving a catheter shaft 103 forming a second component of the balloon catheter 100.

Here, the sealing devices 1 are mounted on the catheter shaft 103 such that the catheter shaft 103 is accommodated in the trough-openings 6 of the sealing devices 1 as described above. Particularly, the annular inner support members 5 are arranged on the catheter shaft 103 and are bonded thereto. Then the end portions 102 of the balloon 101 are arranged on the outer surfaces 3a of the annular deformable sealing members 3 of the sealing devices 1 as described above with reference to Fig. 1. Finally, the annular outer support members 2 are put over the end portions 102 (cf. Fig. 1), wherein said annular outer support members 2 can already be provided on said portions 102 of the balloon 101 (e.g. as integral elements thereof). Heating H now the sealing devices 1 expands them radially as described above and therefore activates the sealing members 1. Cooling the sealing members 1 again, shrinks the annular deformable sealing members 3 and allows the balloon to be released from the annular sealing members 3.

Furthermore, as shown in Fig. 4, in a preferred embodiment of the medical device 100, the catheter shaft 103 can comprise an outer shaft member 103b and an inner shaft member 103a, the inner shaft member 103a being slidably arranged in a lumen of the outer shaft member 103b, so that the catheter shaft 103 is extendable by pulling the inner shaft member 103a partially out of the outer shaft member 103b. This allows one to easily fit balloons of different lengths onto the catheter shaft since the distance between the two sealing members 1 mounted on the catheter shaft is now variable.

Particularly, a distal sealing device 1 as described herein, particularly in conjunction with Fig. 1, can be arranged on a distal end portion of the inner shaft member 3a, wherein the annular inner support member 5 of this sealing device 1 accommodates the distal end portion of the inner shaft member 3a in its through-opening 6 (cf. Fig. 1) and is bonded to the inner shaft member 3a. Furthermore, a proximal sealing device 1’ according to the present invention (as e.g. described in conjunction with Fig. 1 above) is mounted on the catheter shaft at the end of the outer shaft member 103b and has its through-opening 6 delimited by the inner surface 3b of the annular deformable sealing member 3 (i.e. does not comprise an annular inner support member 5). Thus, the annular deformable sealing member 3 of the proximal sealing device 1’ can reversibly clamp also the inner shaft member 3a when the body 4 is brought into its contracted state by increasing the temperature. Particularly, in order to decrease the risk that the inner shaft member 103a is squeezed by the proximal sealing device 1’ in the contracted state of the body 4 of the proximal sealing device 1’, the inner shaft member 103a can comprise supporting structures 104, particularly supporting rings 104. Such a supporting structure/ring 104 can be formed by an X-ray marker of the balloon catheter 100 that is arranged on the inner shaft member 103a.

The present invention provides an advantageous reversible sealing device which in particular increases its circumference under the action of heat and decreases its circumference again under the action of cold. This sealing device is particularly suitable for creating a secure liquid- and gas-tight seal between one space and another under physiological conditions (e.g. at body temperature), but preferably in such a way that the sealing device can be released under non-physiological conditions (e.g. at temperatures below 30 degrees). Furthermore, the sealing device can be used as a clamping element. Particularly, the sealing device according to the present invention offers easy handling under clinical conditions, it is failsafe, easy to sterilize, and very easy to use.

Claims

1. A sealing device (1), particularly for a medical device (100), the sealing device (1) comprising:

- an outer support member (2) comprising an inner surface (2a),

- a deformable sealing member (3) comprising an outer surface (3a), the outer support member (2) being configured to be arranged over the deformable sealing member (3) so that the inner surface (2a) of the outer support member (2) faces the outer surface (3a) of the deformable sealing member (3), and

- a body (4) formed out of a shape memory alloy, wherein the body (4) is surrounded by the deformable sealing member (3), wherein the body (4) extends along an axial direction (x) and is configured to assume an expanded state at a first temperature and a contracted state at a higher second temperature, wherein the body (4) is contracted in the axial direction (x) in said contracted state causing the deformable sealing member (3) to expand in a radial direction (R).

2. The sealing device according to claim 1, wherein the outer surface (3a) of the deformable sealing member (3) is configured to move towards the inner surface (2a) of the outer support member (2) when the latter is arranged over the deformable sealing member (3) and the body (4) assumes its contracted state, allowing to sealingly clamp a circumferential portion (102) of a component (101) in between the inner and outer surface (2a, 3 a).

3. The sealing device according to claim 1 or 2, wherein the body (4) is a structure surrounding an interior space in a circumferential direction (U) that is orthogonal to the axial direction (x), and having an inside (4a) facing said interior space, and having an outside (4b) facing away from the inside (4a).

4. The sealing device according to one of the preceding claims, wherein the deformable sealing member (3) comprises an inner portion (30) arranged on the inside (4a) of the body (4), and an outer portion (31) arranged on the outside (4b) of the body (4).

5. The sealing device according to one of the preceding claims, wherein the deformable sealing member (3) surrounds a through-opening (6) of the sealing device (1), the through-opening (6) being configured for receiving a component, particularly a component (103) of a medical device (100), wherein particularly said component is a shaft of a catheter.

6. The sealing device according to claim 5, wherein the sealing device (1) comprises an inner support member (5), wherein an inner surface (3b) of the deformable sealing member (3) is bonded to the inner support member (5), and wherein the inner support member (5) defines said through-opening (6) and is configured to be bonded to said component received in said through-opening (6).

7. The sealing device according to one of the preceding claims, wherein the first temperature is smaller than 30°C and the second temperature is larger or equal to 35°C.

8. The sealing device according to one of the preceding claims, wherein the body (4) is formed out of a material selected from nickel titanium alloys, copper aluminium nickel alloys, copper zinc aluminium alloys, iron manganese silicon alloys.

9. The sealing device according to one of the preceding claims, wherein the deformable sealing member (3) is formed out of an elastic material, preferably an elastomer, more preferably a thermoplastic elastomer.

10. The sealing device according to one of the preceding claims, wherein the outer support member (2) is an annular outer support member and wherein the deformable sealing member (3) is an annular deformable sealing member and/or the body (4) is an annular body and/or the inner support member (5) is an annular inner support member.

11. A medical device (100), comprising at least one sealing device (1) according to one of the preceding claims, wherein the medical device (100) comprises a first component (101) having a circumferential end portion (102) configured to be arranged between the outer surface (3 a) of the deformable sealing member (3) and the inner surface (2a) of the outer support member (2).

12. The medical device according to claim 11, wherein the first component is a balloon.

13. The medical device (100) according to claim 11 or 12, wherein the medical device (100) comprises a second component (103) configured to be received in the through- opening (6) surrounded by the deformable sealing member (3).

14. The medical device according to claim 13, wherein the second component is a catheter shaft.

15. A method for sealing a medical device (100) using a sealing device (1) according to one of the claims 1 to 10, the method comprising the steps of

- providing a medical device (100) comprising a first component (101),

- arranging a portion (102) of the first component (101) between the inner surface (2a) of the outer support member (2) and the outer surface (3a) of the deformable sealing member (3), and

- heating the body (4) so that the body (4) assumes its contracted state and thereby causes the deformable sealing member (3) to expand in the radial direction (R) so that the outer surface (3a) of the deformable sealing member (3) moves towards the inner surface (2a) of the outer support member (2) and sealingly clamps the circumferential portion (102) of the first component (101) between the inner and outer surface (2a, 3a).