Production of a material composite of titanium and a thermoplastic polyurethane by direct injection molding in the area of a header of an active permanent implant

Abstract

The present invention relates to a method for forming a header (1) on a housing (2) of an implantable medical device (100), the method comprising: providing a housing (2) having a surface (2a) to which the header (1) is to be connected, wherein the surface (2a) is subjected to a pre-treatment to achieve a pre-treated surface (2a), the pre-treatment comprising applying an alkoxysilane to the surface (2a), arranging the housing (2) with respect to a mold (6) for injection molding such that the pre-treated surface (2a) delimits a cavity (60) of the mold (6), and injection molding of at least a portion of the header (1) by filling the cavity (60) with a thermoplastic material, such that the thermoplastic material bonds to the pre-treated surface (2a).

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Date: 07.10.2025

[0003] Our Reference: 23.044P-WO

[0004] Production of a material composite of titanium and a thermoplastic polyurethane by direct injection molding in the area of a header of an active permanent implant

[0005] The present invention relates to a method for forming a header (or at least a portion thereof) of an implantable medical device and to an implantable medical device, particularly an implantable medical device having a header that has been manufactured using the method according to the present invention.

[0006] Particularly, casting of headers of active implants with cold-curing two-component epoxy resins as well as bonding of header assemblies of thermoplastic polyurethanes to titanium housing surfaces with two-component silicone adhesives are known in the prior art.

[0007] However, processing of liquid media (such as two-component epoxy resins or two- component silicone adhesives) is often difficult since the use of such media cannot be easily automated. Furthermore, higher costs are often involved due to necessary mechanical rework after differential pressure casting. Further, the duration for the curing reaction is in the range of hours.

[0008] Based on the above, the problem to be solved by the present invention is to provide a preferably media-tight connection between a header and a housing of an implantable medical device, particularly of components made of titanium or a titanium alloy and polyurethane in the area of the header (e.g. interface between header and housing) of an implantable medical device, particularly of an active implant.

[0009] This problem is solved by a method having the features of claim 1. A further aspect disclosed herein relates to an implantable medical device. Preferred embodiments of the method according to the present invention are stated in the dependent claims and are described below.

[0010] According to claim 1, a method for forming a header (or a portion thereof) on a housing of an implantable medical device is disclosed, the method comprising: providing a housing having a surface to which the header is to be connected, wherein the surface is subjected to a pre-treatment to achieve a pre-treated surface, the pretreatment comprising applying an alkoxysilane to the surface, arranging the housing with respect to a mold for injection molding such that the pretreated surface delimits a cavity of the mold, and injection molding of at least a portion of the header or of the (complete) header by filling the cavity with a thermoplastic material, such that the thermoplastic material bonds to the pre-treated surface.

[0011] Particularly, the housing surface comprises an oxide compound, e.g., a metal oxide such as titanium oxide or aluminum oxide. Particularly, upon applying the alkoxysilane to the surface a bond is formed between the oxide compound and the alkoxysilane, particularly a covalent bond.

[0012] According to an embodiment of the method, the pre-treated surface is heated to a temperature larger than 150 °C prior to injection molding of the header or the at least one portion of the header.

[0013] Furthermore, according to another embodiment of the method, upon the injection molding of the at least one portion of the header or of the complete header the pre-treated hot surface is wetted with the molten thermoplastic material under a pressure being in the range from 500 bar to 1500 bar, particularly in the range from 750 bar to 950 bar.

[0014] According to yet another embodiment of the method, the alkoxy silane is

[0015] N,N-[bis(3-trimethoxysilyl)propyl]ethylenediamine (CAS-No.: 68845-16-9),

[0016] - N-(3-triethoxysilylpropyl)-diethanolamine (CAS-No.: 7538-44-5), (3 -aminopropyl)trimethoxy silane (CAS-No.: 13822-56-5), or

[0017] 23.044P-WO | 07.10.2025 3-(diethoxymethylsilyl)-propylamine (CAS-No.: 3179-76-8).

[0018] In one embodiment, the alkoxysilane is deposited on the surface in form of a solution, particularly by dipping the surface into the solution. In one embodiment, the alkoxysilane solution is an acetic acid ethanolic alkoxysilane solution. In one embodiment, the acid ethanolic solution has an alkoxysilane concentration of at least 0.01 % (w / v). In one embodiment, the acid ethanolic solution has an alkoxysilane concentration in the range of 0.01 % (w / v) to 10 % (w / v). In one embodiment, the acid ethanolic solution has an alkoxysilane concentration in the range of 0.25 % (w / v) to 2.5 % (w / v)

[0019] Further, in an embodiment of the method, pre-treatment of the surface prior to applying the alkoxysilane further comprises at least one of: cleaning the surface, acid cleaning (pickling) of the surface, wet-chemically oxidizing the surface, laser structuring the surface.

[0020] According to a further embodiment, the thermoplastic material is thermoplastic polyurethane. Particularly, said thermoplastic polyurethane is one of: Pellethane 2363-75D, or Tecothane TT-1075D-M (Lubrizol Life Science, Brecksville, Ohio, United States of America) or Elasthane 75D NW (DSM Biomedical B. V., Geleen, the Netherlands).

[0021] According to yet another embodiment of the method, the surface and / or said housing is formed out of titanium or a titanium alloy. Particularly, in an embodiment, the titanium may be a titanium according to the standard ASTM B 265-00, i.e., the alloy comprises besides Ti, less than or equal to 0.20% Fe, less than or equal to 0.18% O, less than or equal to 0.08% C, less than or equal to 0.03% N, less than or equal to 0.015% H, wherein the rest is Ti. Particularly, the entire housing is formed out of titanium, particularly according to said standard ASTM B 265-00.

[0022] According to a further embodiment of the method, the surface of the housing is adjacent an electrical feedthrough of the housing.

[0023] Furthermore, in an embodiment of the method, prior to said injection molding of the header or a portion thereof, an insert for providing an electrical connection between a receptacle for

[0024] 23.044P-WO | 07.10.2025 receiving a plug and said electrical feedthrough is connected to the electrical feedthrough. In a further embodiment of the method, said injection molding further comprises embedding the insert in the thermoplastic material.

[0025] According to a further embodiment of the method, the implantable medical device is one of: a pacemaker, a cardioverter-defibrillator, a neurostimulator, an implantable cardiac monitoring device.

[0026] Furthermore, according to yet a further embodiment of the method, the surface of the housing is adjacent an electrical feedthrough of the housing. Particularly, in an embodiment, prior to said injection molding of the header, an insert for providing an electrical connection between a receptacle for receiving a plug (e.g. of an electrode lead) and said electrical feedthrough is connected to the feedthrough (e.g. to its pins) in an electrically conducting fashion. Particularly, the insert can be arranged in the cavity of the mold together with the housing’s surface that delimits the cavity for molding the header on the surface. Furthermore, the insert can also be pre-fixed to the housing. However, it is also conceivable to position the insert in the mold and connect it to the feedthrough afterwards.

[0027] Particularly, according to a further embodiment of the method, said injection molding of the header further comprises embedding the insert in the thermoplastic material to enclose the insert in the header.

[0028] Furthermore, in an embodiment of the method, the implantable medical device is one of: a pacemaker, a cardioverter-defibrillator, a neurostimulator, a cardiac monitoring device.

[0029] According to a further aspect of the present invention, an implantable medical device is disclosed, wherein the implantable medical device comprises a housing and a header connected a surface of the housing, wherein the header (or at least a portion thereof) is formed on the surface of the housing using the method according to the present invention.

[0030] According to a further aspect of the present invention, an implantable medical device is disclosed, wherein the implantable medical device comprises a housing and a header

[0031] 23.044P-WO | 07.10.2025 connected a surface of the housing, and a layer comprising a siloxane compound is bonded or grafted to the surface of the housing.

[0032] The term “siloxane compound” refers to a compound formed by the reaction of an alkoxysilane with the surface of the housing and / or with itself and having particularly a siloxane bond (-O-Si)-. In one embodiment, the siloxane compound is particularly characterized by a general formula Rl-O-Si(R2)x-(CH2)m-R3, x being 1 or 2, R1 being a metal, R2 being a carbon compound or oxygen, R3 being hydrogen or the thermoplastic material. In one embodiment, the siloxane compound is particularly characterized by a general formula Rl-(O-SiO[R2]x)n-(CH2)m-R3, x being 1 or 2, n being a positive integer having a value of at least 1, R1 being a metal, R2 being a carbon compound or oxygen, R3 being the thermoplastic material. In one embodiment, the siloxane compound is covalently bound the thermoplastic material. In one embodiment, the siloxane is not-covalently bound to the thermoplastic material.

[0033] In the following, embodiments as well as further features and advantages of the present invention shall be described with reference to the Figures, wherein

[0034] Fig. 1 shows a housing of an implantable medical device having a pre-treated surface for generating a header thereon according to an embodiment of the method according to the present invention;

[0035] Fig. 2 shows a mold for injection molding arranged on the housing such that said pre-treated surface of the housing delimits a cavity of the mold; and

[0036] Fig. 3 shows the header connected to the housing after injection molding.

[0037] Fig. 1 shows in conjunction with Figs. 2 and 3 an embodiment of a method according to the present invention. The method allows to injection mold a header 1 (or at least a portion thereof) of an implantable medical device 100 (cf. Fig. 3) to a housing 2 of the device 100, the housing 2 being preferably made of titanium or a titanium alloy or comprising at least a surface 2a formed out of titanium or a titanium alloy as described herein.

[0038] 23.044P-WO | 07.10.2025 Particularly, the media-tight bond between the two joining partners may be produced in the following way. The housing surface 2a is preferably made out of titanium (e.g. Ex. Grade 1, ASTM B 265-00) and can be pre-processed, e.g., cleaned, acid-cleaned, wet-chemically oxidized and / or, in particular, laser-structured. Further, the surface 2a is pretreated with an adhesion promoter from the alkoxysilane class (e.g. N,N-[bis(3- trimethoxysilyl)propyl]ethylendiamine, CAS-No.: 68845-16-9, deposited from acetic acid ethanolic solution by dipping 3 the surface 2a into the solution as indicated schematically in Fig. 1).

[0039] The outer geometry of the header 1 or a portion thereof in the vicinity of the surface 2a is generated by injection molding with a thermoplastic material, preferably a thermoplastic polyurethane, e.g. with Pellethane 2363-75D or Tecothane TT-1075D-M (Lubrizol Life Science, Brecksville, Ohio, United States of America), or , Elasthane 75D NW (DSM Biomedical B.V., Geleen, the Netherlands).

[0040] Particularly, said pre-treated surface 2a on which the header 1 is later to be located delimits a cavity 60 of a mold 6 (cf. Fig. 2) used for injection molding. The surface 2a is heated above 150 °C and the thermoplastic material is injected into the cavity 60 of the mold 6 under high pressure, e.g. in the range from 500 bar to 1500 bar, particularly in range from 750 bar to 950 bar, so that the molten thermoplastic material may directly wet the hot pre-treated surface 2a.

[0041] Prior to injecting the thermoplastic material into the cavity 60 of the mold 6, and particularly prior to arranging the housing 2 with respect to the mold, a header assembly 7 may be connected to an electrical feedthrough 20 of the housing 2, which feedthrough 20 is arranged adjacent said surface 2a. The header assembly 7 comprises electrical contacts 41, 42, 43, 44 for electrically contacting a plug of an electrode lead. The header assembly 7 may further comprises electrical conductors 50, e.g. designed as wires or ribbons that connect the contacts 41, 42, 43, 44 to feedthrough-pins 21 of the feedthrough 20 via contacts 500 of the electrical conductors 50. Thus, the header contacts 41, 42, 43, 44 may be connected to an electronic circuit accommodated in the housing 2 via the feedthrough 20.

[0042] 23.044P-WO | 07.10.2025 Furthermore, the header assembly 7 may comprise an antenna 40, wherein the antenna 40 may be connected to a feedthrough-pin 21 as well via a contact 501. Particularly, the components of the header assembly 7 may be separate parts but may also be connected to one another in a suitable manner so that the header assembly 7 may be positioned relative to the housing 2 and particularly connected thereto at once.

[0043] For example, the electrical contacts 41, 42, 43, 44 may be provided in form of one or more pre-assembled header sub-assembly (header core) comprising one or more continuous receiving units for receiving a plug of an electrode lead formed by a plastic material in which the electrical contacts 41, 42, 43, 44 are arranged. The one or more header sub-assemblies may be arranged on the housing 2, and subsequently the electrical contacts 41, 42, 43, 44 may be connected to the feedthrough pins 21 via the electrical conductor(s) 50, e.g., by welding.

[0044] It is conceivable to position the housing 2 together with the header assembly 7 connected thereto with respect to the mold 6. However, it is also possible to position the housing 2 with respect to the mold 6 and then place the header assembly 7 into the mold and connect it to the feedthrough 20.

[0045] To form one or more receptacles required for and configured to receive a plug of an electrode lead, one more casting aid, e.g. mandrils are arranged in the cavity of the mold 6 to injecting the thermoplastic material. The one or more casing aids may be for example arranged in the or more continuous receiving units in the above described one or more header subassemblies or through the electrical contacts 41, 42, 43, 44. After injection of the thermoplastic material in the cavity, the casting aids are removed.

[0046] The present invention offers the advantage that the processing of two-component epoxy resins that often requires mechanical reworking can be avoided. Furthermore, an automated assembly of the header is possible (including external wiring, etc.). Furthermore, no additional bonding steps are necessary, which allows a reduction of the total number of process steps.

[0047] 23.044P-WO | 07.10.2025

Claims

1. - 8 -Claims1. A method for forming a header (1) on a housing (2) of an implantable medical device (100), the method comprising: providing a housing (2) having a surface (2a) to which the header (1) is to be connected, wherein the surface (2a) is subjected to a pre-treatment to achieve a pre-treated surface (2a), the pre-treatment comprising applying an alkoxy silane to the surface (2a), arranging the housing (2) with respect to a mold (6) for injection molding such that the pre-treated surface (2a) delimits a cavity (60) of the mold (6), and injection molding of at least a portion of the header (1) by filling the cavity (60) with a thermoplastic material, such that the thermoplastic material bonds to the pre-treated surface (2a).

2. The method according to claim 1, wherein the pre-treated surface (2a) is heated to a temperature larger than 150 °C prior to injection molding of the at least one portion of the header (1).

3. The method according to claim 1 or 2, wherein upon the injection molding of the at least one portion of the header (1) the pre-treated surface (2a) is wetted with the molten thermoplastic material under a pressure being in the range from 500 bar to 1500 Pa, particularly in the range from 750 bar to 950 bar.

4. The method according to one of the preceding claims, wherein the alkoxy silane isN,N-[bis(3-trimethoxysilyl)propyl]ethylenediamine, N-(3 -tri ethoxy silylpropyl)-di ethanolamine, (3 -aminopropyl)trimethoxy silane, or 3-(diethoxymethylsilyl)-propylamine.

5. The method according to one of the preceding claims, wherein pre-treatment of the surface prior to applying the alkoxysilane further comprises at least one of: cleaning23.044P-WO | 07.10.2025- 9 - the surface (2a), acid cleaning of the surface (2a), wet-chemically oxidizing the surface (2a), laser structuring the surface (2a).

6. The method according to one of the preceding claims, wherein the thermoplastic material is thermoplastic polyurethane.

7. The method according to one of the preceding claims, wherein the surface (2a) and / or said housing (2) is formed out of titanium or a titanium alloy.

8. The method according to one of the preceding claims, wherein the surface (2a) of the housing (2) is adjacent an electrical feedthrough (20) of the housing (2).

9. The method according to one of the preceding claims, wherein prior to said injection molding of the header (1), an insert (7) for providing an electrical connection between a receptacle (30, 31) for receiving a plug and said electrical feedthrough (20) is connected to the electrical feedthrough (20).

10. The method according to claim 9, wherein said injection molding of the header (1) further comprises embedding the insert (7) in the thermoplastic material.

11. The method according to one of the preceding claims, wherein the implantable medical device (100) is one of: a pacemaker, a cardioverter-defibrillator, a neurostimulator, or an cardiac monitoring device.

12. The method according to one of the preceding claims, the header (1) is injection molded by filling the cavity (60) with the thermoplastic material, such that the thermoplastic material bonds to the pre-treated surface (2a).

13. An implantable medical device, comprising a housing (2) and a header (1) connected to a surface (2a) of the housing (2), wherein the header (1) is formed on the surface (2a) of the housing (2) using the method according to one of the preceding claims.23.044P-WO | 07.10.20254. An implantable medical device, comprising a housing (2) and a header (1) connected to a surface (2a) of the housing (2), wherein a layer comprising a siloxane compound is bonded to the surface (2a) of the housing (2).23.044P-WO | 07.10.2025

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