Method for manufacturing a head portion of an implantable medical device

Abstract

A method for manufacturing a head of an implantable medical device is described, the head having a head shell, the head shell having a recess in the form of a blind hole, at least one electrically conductive contact ring element and at least one electrically insulating elastically deformable sealing ring being joined together in a force-fitting manner under an axial joining force in a coaxial arrangement and in an axial sequence along the recess, wherein the at least one contact ring element is arranged together with the at least one sealing ring along a rod-shaped assembly tool and joined together in a force-fitting manner along the rod-shaped assembly tool by generating a joining force, wherein the at least one contact ring element and the at least one sealing ring arranged at least along the rod-shaped assembly tool and joined in a force-fitting manner are encapsulated with a solidifiable casting material in a flowable form. The method is characterized in that the generation of the engagement force between the at least one contact ring element and the sealing ring is implemented along the assembly tool with the aid of attachment devices installed on both sides of the at least one contact ring element and the sealing ring along the assembly tool, at least one of the attachment devices can be axially movably and detachably fixed to the assembly tool in an axially stable manner and is designed in the form of a nut with an internal thread, the internal thread meshing with an external thread arranged along the assembly tool, so that the attachment device designed in the form of a nut is engaged with the at least one contact ring element or the sealing ring in a force-fitting manner on one side by relative rotation along the external thread of the assembly tool to form an engagement force, and the rod-shaped assembly tool is released and removed from the at least one contact ring element and the at least one sealing ring after the casting material solidifies, and the casting material forming at least a part of the head shell in the form of a dimensionally stable matrix mechanically supports the axial engagement force.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a head of an implantable medical device, wherein the head has a head shell, the head shell has a recess in the form of a blind hole, at least one electrically conductive contact ring element and at least one electrically insulating elastically deformable sealing ring are joined together in a coaxial arrangement and in an axial sequence along the recess in a force-fitting manner under an axial joining force. Background Art

[0002] Implantable medical devices for electrical stimulation of localized internal body regions, such as short-term implantable pulse generators (IPGs) for cardiac defibrillation, pacemaker and resynchronization applications, for neurostimulation treatment measures (e.g. spinal cord stimulation, brain stimulation or vagus nerve stimulation), usually have a separate housing in which components for generating electrical pulses, such as at least one electrical energy source and a circuit structure connected to the electrical energy source, are accommodated. In addition, the housing is connected to a so-called "head" in which an electrical contact arrangement is accommodated, the electrical contact arrangement being electrically connected to the energy source and / or the circuit structure, into which a connector arrangement can be introduced, the electrical contact arrangement being sealed by the head in a fluid-impermeable manner, the connector arrangement being in contact with the supply and discharge lines for locally applying electrical stimulation signals in the body and, if necessary, providing the circuit structure located in the housing with electrical signals for local tapping in the body.

[0003] Publication EP 2 134 418 B1 describes a universal head for an implantable medical device, comprising two head housing halves, which can be joined together along a seam, into each of which semi-cylindrical recesses are introduced in sequence, separated by spacers, into each of which recesses are introduced in a sequence of alternating sequences, electrically conductive contact ring elements and electrically insulating sealing rings. Thus, the head assembled from the two head housing halves thus comprises a coaxially aligned arrangement and electrically insulating contact ring elements for making electrical contact, a lateral passage being provided in the head, through which an electrical connector arrangement can be introduced in a fluid-impermeable manner into a cavity surrounded by all annular contact ring elements.

[0004] Publication DE 10 2012 010 901 A1 discloses a method for positioning and holding electrical contacts and seals in a head for making electrical contact with a medical implantable device. In a head housing consisting of a biocompatible and electrically insulating material, a hole in the form of a blind hole is introduced at one side, into which holes conductive contact rings and annular sealing elements are introduced in an alternating sequence, which together enclose a cavity into which a rod-shaped connector arrangement can be introduced. Each of the individual annular contact rings in the head is connected to an electrical component located in the housing of the medical implantable device via an electrical connection line.

[0005] In order to achieve a fluid-tight and as durable a seal as possible and to electrically insulate the individual electrical contact ring elements from one another, the alternating sequence of electrical contact ring elements and sealing rings must be fixed in the head with the greatest possible axial force. This requires complex assembly measures that can usually only be performed manually and require a considerable degree of dexterity.

[0006] A connector hole module assembly is disclosed in the publication DE 20 2013 012 073 U1. To assemble the connector hole module assembly, a plurality of contact rings and sealing elements are arranged in an alternating sequence along a rod-shaped assembly tool. With the aid of a clamping device, all contact rings and sealing elements arranged along the assembly tool are clamped together under the application of an axial engagement force. In order to maintain the engagement force, a bushing element is used, which is arranged on the assembly tool in an axially stable manner with the aid of a flat head screw and, together with the assembly tool head at one end, axially limits the arrangement of the contact rings and sealing elements at both ends. In this clamped state, the arrangement is encapsulated with a curable casting material, which supports the engagement force in the cured state. Summary of the invention

[0007] The basic object of the present invention is to further develop a method for producing a head of an implantable medical device, the head having a head housing with a recess in the form of a blind hole, along which at least one electrically conductive contact ring element and at least one electrically insulating, elastically deformable sealing ring are joined together in a coaxial arrangement and in an axial sequence with a force fit under an axial joining force, so that the process complexity and the expenditure in terms of time and cost for the production of individually assembled heads and heads produced in large numbers are significantly reduced. In addition, it is of particular concern that the manufacturing quality as well as the impermeability to fluids and the associated service life of the head must meet the highest requirements.

[0008] The solution of the basic object of the invention is described in the technical solution of the present application. Features that further develop the inventive concept in an advantageous manner are the subject of further technical solutions of the invention and can also be found in the description, in particular with reference to the illustrated embodiments.

[0009] According to a feature of the invention, a method according to the solution for producing a head portion of an implantable medical device comprises the following method steps.

[0010] At least one electrically conductive contact ring element is arranged together with at least one electrically insulating sealing ring composed of an elastically deformable material along a rod-shaped assembly tool, which is preferably designed as a rod, a bar or a pin. The arrangement is achieved simply by screwing a preferably large number of contact ring elements and sealing rings onto the rod-shaped assembly tool, the contact ring elements and sealing rings being arranged in a respectively continuous alternating sequence.

[0011] The at least one contact ring element and the at least one sealing ring are then joined together in a force-fitting manner, i.e., joined to each other, by means of a joining force directed along the rod-shaped assembly tool. In this way, the at least one sealing ring, which is electrically insulating and elastically deformable, rests tightly against the surface of the electrically conductive contact ring element facing the sealing ring, thereby forming a fluid-impermeable annular force-loaded joint.

[0012] In order to generate an engagement force acting axially between the at least one contact ring element and the sealing ring along the rod-shaped assembly tool, attachment devices are mounted on both sides of the at least one contact ring element and the sealing ring along the assembly tool; at least one of these attachment devices is axially movable and removably fixed to the assembly tool in an axially stable manner and is designed in the form of a nut with an internal thread, which meshes with an external thread arranged along the assembly tool, so that the attachment device designed in the form of a nut is engaged with at least one contact ring element or the sealing ring on one side in a force-fitting manner by relative rotation along the external thread of the assembly tool and thereby forming an engagement force. The relative longitudinal adjustability of the attachment device along the assembly tool depends on the threaded engagement between the internal thread of the attachment device designed in the form of a nut and the external thread mounted on the assembly tool, so that the engagement force can be finely adjusted, and the engagement force can be generated only by rotating the assembly tool relative to the attachment device. The assembly tool preferably has a tool head, which has a tool flange located at one end, for example for removably and firmly engaging with a rotating tool in the form of a flat or cross head screwdriver or an Allen key or the like.

[0013] The attachment device designed in the form of a nut can be formed in a variety of different ways in terms of structure. In addition to the conventional nut, a plate element can also be provided, which has at least one threaded hole with an internal thread. By providing two or more threaded holes in the plate element, the number of separate adjacently arranged arrangement structures can be specified as required, and the arrangement structures respectively have a coaxial sequence of contact ring elements and sealing rings and are arranged and scaled adjacent to each other in space within the head. In this way, the head can be designed to have multiple electrical connection sockets, and this is a compact and easy to implement construction form. In addition, the use of a plate element makes it possible to specify a specific spatial relative arrangement between two or more electrical connection sockets arranged in the head.

[0014] By dimensioning the axial thread lengths of the internal thread and the external thread so that they match one another, and by means of a corresponding maximum prescribable rotation of the assembly tool within the internal thread of the attachment device, a defined, prescribable maximum engagement force between the contact ring element and the sealing ring can be structurally specified, thereby enabling the assembly process to be carried out in a reliable and repeatable manner.

[0015] In a preferred embodiment, the rod-shaped assembly tool has a mechanical stop at its head end, which is connected to the head end in an axially stable manner, the mechanical stop is connected to the assembly tool in a detachably fixed or integrated manner, and the axial stacking arrangement composed of the at least one contact ring element and the sealing ring element rests on one side of the stop in a supporting manner. An attachment device in the form of a nut is installed in a manner opposite to the mechanical stop for the axial stacking arrangement, which attachment device can move along the rod-shaped assembly tool and can be axially detachably and firmly connected to the assembly tool.

[0016] The prefabricated assembly tool with the at least one electrically conductive contact element and the at least one sealing ring represents a semi-finished product that can be processed as a unit and encapsulated with a casting compound in a further method step. For this purpose, the at least one contact ring element and the at least one sealing ring, which are arranged along the rod-shaped assembly tool and are connected together in a force-fitting manner, are encapsulated with a curable casting compound in a flowable form. By virtue of the at least one contact ring element and the sealing ring being joined to each other in a form-fitting manner that is impermeable to fluids, the flowable casting compound cannot penetrate into the interior space jointly enclosed by the at least one contact ring element and the sealing ring.

[0017] The casting material is preferably a biocompatible plastic or resin compound, preferably an epoxy resin, which completely solidifies after a short time, thereby forming a dimensionally stable object. After the casting material has solidified, the rod-shaped assembly tool is finally released and removed from the at least one contact ring element and the sealing ring. The axial engagement force acting between the at least one contact ring element and the sealing ring remains unchanged and is completely maintained by the solidified casting material in the form of a dimensionally stable matrix forming at least a part of the head housing. The attachment means designed in the form of a nut remain in the solidified casting material.

[0018] In order to facilitate the release and removal of the assembly tool from the head, before casting with a flowable casting material, the end of the assembly tool that protrudes through the internal thread of the attachment device designed in the form of a nut is moistened with a protective compound, preferably silicone or the like; this prevents the solidified casting material from forming a strong bond with the protruding end section of the assembly tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described below by way of example with reference to the accompanying drawings in an exemplary manner by way of examples of embodiments without limiting the general concept of the present invention.

[0020] Figure 1 A schematic diagram showing an axially stacked arrangement of contact ring elements and sealing rings along a rod-shaped assembly tool,

[0021] Figure 2a , 2b shows a detailed view of the design of an attachment means which can be detachably mounted in an axially stable manner along a rod-shaped assembly tool,

[0022] Figure 3 The method steps of encapsulating a stacked arrangement of contact ring elements and sealing rings mounted on a rod-shaped assembly tool with a casting compound are shown, and

[0023] Figure 4 The solidified casting material and the enclosed stacked arrangement of contact ring elements and sealing rings are shown. DETAILED DESCRIPTION

[0024] Figure 1 Schematically, a rod-shaped assembly tool 1 is shown, along which electrically conductive contact ring elements 2 and electrically insulating sealing rings 3 made of elastomeric material are arranged in an axially continuous alternating sequence. On both sides of an axially stacked arrangement 4 consisting of an alternating sequence of contact ring elements 2 and sealing rings 3, attachment means 5, 6 are mounted along the rod-shaped assembly tool 1. Figure 1In the case of the device 5 shown, the device 5 takes the form of a mechanical stop designed in the form of a plate or disk, which is connected to the otherwise rod-shaped assembly tool 1 and is connected integrally with the assembly tool; the axial stacking structure 4 is directly adjacent to the stop on one side. The attachment device 6 arranged opposite the stop along the axial stacking structure 4 is designed to be able to move axially along the rod-shaped assembly tool 1 and also has a locking mechanism that can fix the attachment device 6 so that the attachment device 6 is fixed axially relative to the rod-shaped assembly tool 1.

[0025] Figure 2a and 2b A preferred embodiment for realizing an axially movable and axially securely lockable attachment means 6 is shown. Figure 2a A nut 10 is shown with an internal thread which engages with an external thread 11 provided at one end of a rod-shaped assembly tool 1. The attachment device 6 designed as a nut 10 need not necessarily be designed as a conventional nut; in fact, any body or body shape with an internal thread 18 can be used as the attachment device 6. Figure 2b A plate element 10' is shown as an attachment device 6, which provides two openings arranged adjacent to each other, each of which has an internal thread 18, into each of which the assembly tool 1 can engage with its external thread 11. The plate element 10' can be shaped and dimensioned in any two-dimensional or three-dimensional manner. In addition, any number of openings with internal threads 18 can be introduced into the plate element 10'. In this way, a plurality of arrangements can be realized in the head, each arrangement consisting of a coaxially arranged contact ring element 2 and a sealing ring 3, and each arrangement serving as an electrical plug socket for the connector unit. Depending on the design of the plate element 10' and the number and arrangement of the openings provided with the internal threads 18 in the plate element 10', a head of any complexity can be realized without a large manufacturing and assembly expenditure.

[0026] The alternating sequence of contact ring elements 2 and sealing rings 3 is joined together in a force-fitting manner, i.e., one to another, by means of a joining force, which is axially directed relative to the rod-shaped assembly tool 1, and in order to apply the joining force, which is axially directed relative to the rod-shaped assembly tool 1, the assembly tool 1 must be rotated relative to the nut 10 or relative to the plate element 10', for example by rotating the outer thread 11 on the end of the assembly tool completely into the inner thread 11, thereby setting a defined, prescribable joining force acting along the contact ring elements 2 and the sealing rings 3 located on the assembly tool. In the simplest case, the relative rotation can be achieved by a rotating tool, for example in the form of a spanner, which can engage with the assembly tool.

[0027] Figure 1The axially stacked arrangement 4 shown, consisting of a plurality of electrical contact ring elements 2 and sealing rings 3, which are screwed together in an alternating sequence to a rod-shaped assembly tool 1 and joined together by means of attachment means 5 and 6 under the specification of an axially acting joining force F, represents a semi-finished product to be processed manually or automatically as a unit, which is then Figure 3 The illustrated method uses a solidifiable casting compound 12 encapsulated in a flowable form. A casting mold 13 is advantageously used for this purpose, into which the above-described semi-finished product with axially preloaded contact ring elements and sealing rings and assembly tools is introduced. The casting mold 13 is then filled with the flowable casting compound 12, wherein the casting compound 12 surrounds the entire stacked arrangement 4, i.e. the attachment means 6 and all contact ring elements and sealing rings, and preferably also at least partially surrounds the attachment means 5.

[0028] After the casting material 12 is solidified, the assembly tool 1 is removed. Figure 4 , wherein the attachment means 6 and the axially stacked arrangement 4 remain in the casting material 12. If the attachment means 5 is not Figure 1 Instead of being integral as shown, the attachment means 5 can be releasably fixedly mounted on the assembly tool in the same way as the attachment means 6 , in which case the attachment means 5 can also remain in the solidified casting material.

[0029] In order to prevent the end of the assembly tool 1 protruding beyond the internal thread 18 of the attachment means 6 from forming a strong material bond with the solidified casting compound 12 which would make it at least more difficult to release the assembly tool 1, the end of the assembly tool is moistened with a protective compound 19 (e.g. silicone or the like) before casting, see Figure 2a .

[0030] After the assembly tool 1 is removed, the axial engagement force F existing between the contact ring element 2 and the sealing ring 3 remains unchanged, in particular because the engagement force F is supported by the solidified casting material 12. Figure 3 The manufacturing steps shown in which the joining force F is generated and maintained on both sides by the attachment means 5 and 6 are different. Figure 4 In this case, after removal of the assembly tool 1 , the joining force F is supported or supported only by the solidified casting material 12 and remains unchanged by virtue of the dimensional stability of the solidified casting material.

[0031] At the same time, after removal of the assembly tool 12 , an open passage 15 in a cavity is formed in the head 14 formed by solidification of the casting compound, into which cavity a connector structure not shown can be introduced in order to make electrical contact with the respective electrical contact ring element 2 .

[0032] An electrical conductor structure 16 also emerges from each electrically conductive contact ring element 2; this conductor structure projects through the head 14 on one side and is connected to an electrical component in an implantable medical device 17. For this purpose, the electrical conductor structure can already be connected to the corresponding electrical contact ring element before the semi-finished product is cast and cast together with the described semi-finished product. Alternatively, the electrical conductor structure can be contacted with the contact ring element afterwards by drilling a hole in the solidified matrix and appropriately inserting the conductor structure into the hole.

[0033] As mentioned in the introduction, the implantable medical device 17 is preferably an encapsulated pulse generator for generating an electrical stimulation signal that can be delivered to the patient via a non-invasive Figure 4 The connector unit and associated wires shown in are applied to a specific internal body region. The head 14 is usually attached to the medical device 17 so that it can be removed and so that, for example, a pulse generator can be replaced without affecting the wires located in the body.

[0034] Reference numerals list

[0035] 1 Rod-shaped assembly tool

[0036] 2 Conductive contact ring element

[0037] 3 Electrically insulating sealing ring

[0038] 4 Stacked layout

[0039] 5.6 Attachment Devices

[0040] 7 Bushing

[0041] 8 Internal threaded hole

[0042] 9 Flat head screw

[0043] 10 Nut

[0044] 10' Plate Element

[0045] 11 External thread

[0046] 12 Casting materials

[0047] 13 Casting mold

[0048] 14 Head

[0049] 15 Lumen, open passage

[0050] 16 Electrical conductor structure

[0051] 17 Implantable medical devices

[0052] 18 Internal thread

[0053] 19 Protective compounds

[0054] D Rotation

[0055] F Bonding force

Claims

1. A method for producing a head (14) of an implantable medical device (17), the head having a head shell, the head shell having a recess in the form of a blind hole, at least one electrically conductive contact ring element (2) and at least one electrically insulating, elastically deformable sealing ring (3) being joined together in a coaxial arrangement and in an axially continuous sequence along the recess in a force-fitting manner under an axial joining force, wherein: The at least one contact ring element (2) and the at least one sealing ring (3) are arranged together along a rod-shaped assembly tool (1) and joined together in a force-fitting manner along the rod-shaped assembly tool (1) by generating a joining force (F), wherein: The at least one contact ring element (2) and the at least one sealing ring (3) which are arranged at least along a rod-shaped assembly tool (1) and joined in a force-fitting manner are encapsulated with a solidifiable casting compound (12) in a flowable form, The generation of the engagement force (F) between the at least one contact ring element (2) and the sealing ring (3) along the assembly tool (1) is implemented by means of attachment devices (5, 6) installed on both sides of the at least one contact ring element (2) and the sealing ring (3) along the assembly tool (1), wherein the attachment devices are in contact with the contact ring element (2) or the sealing ring (3), and at least one of the attachment devices (6) is axially movably and detachably fixed to the assembly tool (1) in an axially stable manner and is designed in the form of a threaded hole with an internal thread, and the internal thread is connected to the assembly tool (1) along the assembly tool (1). 1) is engaged with an external thread (11) provided on the head shell, so that the attachment device (6) designed to have a threaded hole is engaged with at least one contact ring element (2) or a sealing ring (3) in a force-fitting manner on one side by relatively rotating along the external thread (11) of the assembly tool (1), thereby forming a joining force (F), and the rod-shaped assembly tool (1) is released and removed from the at least one contact ring element (2) and the at least one sealing ring (3) after the casting material (12) is solidified, and the casting material (12) forming at least a part of the head shell in the form of a dimensionally stable matrix mechanically supports the axial joining force (F), wherein after release and removal of the assembly tool (1), at least one attachment means (6) remains in the solidified casting material (12), wherein before encapsulation and solidification of the casting material (12), the at least one contact ring element (2) is connected to at least one electrical conductor structure (16) which is led through the casting material (12), and After the assembly tool (1) is removed, the joining force (F) is supported or carried only by the solidified casting material (12). One of the attachment devices (5, 6) is constructed as a detachable part so as to be removable from the assembly tool (1), the other of the attachment devices (5, 6) is constructed to be integrally formed with the assembly tool, the one of the attachment devices (5, 6) can be designed as a nut shape with a threaded hole or a plate-like piece with at least two threaded holes, and after releasing and removing the assembly tool (1) and the other attachment device (5), the one of the attachment devices (5, 6) remains in the solidified casting material.

2. The method according to claim 1, It is characterized in that A plurality of contact ring elements (2) and a plurality of sealing rings (3) are provided which are arranged in a continuous alternating sequence along a rod-shaped assembly tool (1).

3. The method according to claim 1 or 2, It is characterized in that The encapsulation of the at least one contact ring element (2) and the sealing ring (3) arranged along a rod-shaped assembly tool (1) and joined in a force-fitting manner is achieved using a casting mold (13).

4. The method according to claim 1 or 2, It is characterized in that After the rod-shaped assembly tool (1) is released and removed from the at least one contact ring element (2) and the sealing ring (3), an open passage is formed in the head (14) leading to the cylindrical volume area enclosed by the at least one contact ring element (2) and the sealing ring (3).

5. The method according to claim 1 or 2, It is characterized in that The head (14) is designed for mechanical and electrical coupling to an implantable medical device (17), which is designed as a pulse generator.

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