Method For Producing An Electrode Lead Or A Catheter, And Associated Semifinished Product

Abstract

A method for producing a medical electrode lead or a catheter, and also to an associated semifinished product. The semifinished product for this purpose includes a cable having at least one electrical conductor, which is embedded in a sheath made of an electrically insulating, thermoplastic material. It is characterized in that the cable, at least at one cable end, forms a connection point, via which the conductor can be attached permanently and non-detachably to further components, wherein part of the surface of the conductor is exposed in the region of the connection point and forms a contact face, and the sheath has, in the region of the connection point, a recess that is continuous in the longitudinal direction of the cable.

Claims

1. A semifinished product for producing an electrode lead or a catheter, which semifinished product comprises: a cable having at least one electrical conductor, which is embedded in a sheath made of an electrically insulating, thermoplastic material, wherein the cable, at least at one cable end, forms a connection point, via which the conductor can be attached permanently and non-detachably to further components, and wherein: part of the surface of the conductor is exposed in the region of the connection point and forms a contact face, and the sheath has, in the region of the connection point, a recess that is continuous in the longitudinal direction of the cable.

2. The semifinished product according to claim 1, in which the conductor, at least in the region of the contact face of the connection point, consists of a metal layer applied to the sheath.

3. The semifinished product according to claim 2, in which the metal layer is formed: (i) from at least one noble metal or at least one noble metal alloy, or (ii) from a copper line covered by at least one noble metal or at least one noble metal alloy.

4. The semifinished product according to claim 2, in which the metal layer has a width ranging from 5 to 100 μm.

5. The semifinished product according to claim 2, in which the metal layer has a thickness ranging from 0.1 to 25 μm.

6. The semifinished product according to claim 2, in which the metal layer has an elevation in the region of the contact face.

7. The semifinished product according to claim 1, in which the contact face is 1 μm.sup.2 to 1 mm.sup.2 in size.

8. The semifinished product according to claim 1, in which the thermoplastic material of the sheath is selected from the group comprising polyethylene (PE), poly-propylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), polyether ether ketone (PEEK), liquid-crystal polymers, polyurethane, and copolymers of polyurethane.

9. The semifinished product according to claim 1, in which the contours of the recess and of the sheath in the region of the connection point when combined give a cylinder which surrounds the conductor, and the recess has the shape of a segment of a circle of which the angle subtended by an arc at the center a has a value in the range of from 90° to 270°.

10. The semifinished product according to claim 9, in which the arc at the center a has a value in the range of from 135° to 225°.

11. The semifinished product according to claim 1, in which the contours of the recess and of the sheath in the region of the connection point when combined form a cuboid, which surrounds the conductor, and a volume of the recess lies in the range of from 75% to 125% of the volume of the sheath in the region of the connection point.

12. The semifinished product according to claim 11, in which the cuboid of the sheath has a thickness ranging from 10 to 500 μm.

13. The semifinished product according to claim 1, in which a contour of the recess is not congruent with a contour of the remaining part of the sheath in the region of the connection point.

14. A method for producing an electrode line or a catheter, wherein the method comprises the following steps: a) providing a first and a second semifinished product, wherein each semifinished product comprises a cable having at least one electrical conductor, which is embedded in a sheath made of an electrically insulating, thermoplastic material, and wherein that the cable, at least at one cable end, forms a connection point via which the conductor can be attached permanently and non-detachably to further components, wherein: part of the surface of the conductor is exposed in the region of the connection point and forms a contact face, and the sheath has, in the region of the connection point, a recess that is continuous in the longitudinal direction of the cable, and wherein a contour of the recesses of the connection point of the first semifinished product corresponds substantially to a contour of the sheath in the region of the connection point of the second semifinished product; b) positioning the two semifinished products in a tool in such a way that the connection points rest on one another in a matching manner, such that the contact faces of the two conductors contact one another and the contours of the connection points of the two semifinished products engage with one another; and c) thermally melting the thermoplastic material in the region of the connection points.

15. The method according to claim 14, in which step c) (thermal melting) comprises a heating of the material from a temperature in the range of 80° C. to 450° C. for a period in the range of 1 sec to 30 min.

16. The method according to claim 13, in which the connection points in step c) are exposed in step c), or immediately after step c), to a pressure in the range of 1 to 40 bar.

Description

DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be explained in greater detail hereinafter on the basis of exemplary embodiments and the associated drawings, in which:

[0040] FIG. 1 shows a schematic illustration of part of a semifinished product in the region of the connection point according to the present invention;

[0041] FIG. 2 shows a heavily schematic illustration of a cuboidal connection point in accordance with a further embodiment;

[0042] FIG. 3 shows a schematic illustration of two complementary, cuboidal connection points;

[0043] FIG. 4 shows a schematic illustration of the method for producing the electrical connection;

[0044] FIG. 5 shows a schematic sectional view through the region of the connection point after completion of the connection method;

[0045] FIG. 6 shows a further alternative embodiment of the connection point; and

[0046] FIG. 7 shows a further schematic illustration of a connection point between two complementary semifinished products in accordance with a further embodiment.

DETAILED DESCRIPTION

[0047] FIG. 1 shows, in a heavily schematic way, a region of a semifinished product 10 serving for the production of a flexible electrode or a flexible catheter for medical use. The semifinished product 10 contains, inter alia, a cable 12 having a cable end 14 embodied in a particular way. An electrical conductor 16, which is surrounded by a sheath 18 made of an electrically insulating and thermoplastic material, such as, for example, a liquid-crystal polymer or polyurethane, is disposed in the cable 12. The cable 12 can also have a further sheathing, provided this is advisable for the particular application.

[0048] As can be seen, the cable end 14 is part of the cable 12, i.e., the same sheath material is used for the connection point 20 described below in greater detail.

[0049] The connection point 20 is characterized in that parts of the sheath 18 have been removed. This therefore results in the recess 22 indicated by the dashed line, and in the embodiment illustrated here the sheath 18 assumes the form of a half-cylinder 24 in the region of the connection point 20. Of course, the angle subtended by an arc at the center a can also be defined as deviating from 180°, such that a contour of the recess 22 and of the sheath 18 in the region of the connection point 20 is no longer identical.

[0050] A metal layer 26 is applied to the half-cylinder 24 of the sheath 18 in the region of the connection point 20. By way of example, such a structure can be produced by metal deposition of gold or palladium. It is also conceivable to first apply a copper layer, the surface of which is in turn refined with gold or palladium. The specified materials have a particularly high conductivity.

[0051] FIG. 2 in a heavily simplified manner shows merely a particular embodiment of the connection point 20 in which the part of the sheath 18 still present assumes the form of a cuboid. A metal layer 26 made of gold is in turn applied to this cuboid. The cuboid can consist of a thermoplastic liquid-crystal polymer.

[0052] FIG. 3 now illustrates how an identically constructed mating piece is oriented and positioned relative to the connection point 20 illustrated in FIG. 2 such that the metal structures come to lie on one another at a point and therefore provide an electrical contact face between the two conductors. Here, connection points 20 each having a conductor 16 running longitudinally are illustrated. However, a plurality of conductors running in parallel or conductors running differently can also be connected to one another. It is also conceivable for the metal structures to contact one another only at individual points when they are laid one on top of the other.

[0053] By means of a suitable tool 30, for example, a metal die with integrated heater, a pressure of from 1 to 40 bar is applied in order to produce the electrical connection, and the tool 30 is temporarily heated from the ambient temperature to between 80° C. and 450° C. and is cooled again (see FIG. 4). As can be seen, the contact faces of both conductors 16 of the corresponding connection points 20 lie opposite one another. The thermal treatment is maintained for 1 sec to 30 min. After cooling to ambient temperature, the tool 30 is removed again. The tool 30 can have a form which is molded into the plastic material during the heating process. The tool 30 can also be coated with Teflon or a ceramic so as to prevent the thermoplastic from adhering to the tool 30. After the pressing, a homogeneous plastics body is produced, in which the metal layers 26 are embedded in a manner lying against one another (see FIG. 5).

[0054] In order to improve the contact faces between the metal structures and the connection point 20, a gold particle 32 can be added (see FIG. 6). The particle 32 can lie in a small opening in the plastic and is deformed during the pressing.

[0055] FIG. 7 shows a further embodiment of the connection point 20 of two complementary semifinished products. Here, the two connection points 20 have structures that are coordinated with one another in a matching manner. The connection point 20 illustrated on the left-hand side in FIG. 7 thus forms a niche 40, for which the connection point illustrated on the right-hand side has a corresponding lug 42. In this way, the contact faces of the two conductors 26 can lie on one another in an exact manner. The dimensions, for example, comprise 5 to 100 μm width of the metal structures, 0.1 to 25 μm thickness of the metal structures, and approximately 1 μm.sup.2 to 1 mm.sup.2 size of the contact face (overlap of opposing metal layers 26).

[0056] The metal layers can be applied to the plastic material chemically, electrochemically (galvanically) or by vacuum processes or combinations thereof. It is also conceivable to laminate metal onto the support and to structure t using known methods.

[0057] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range.

LIST OF REFERENCE NUMERALS

[0058] 10 semifinished product [0059] 12 cable [0060] 14 cable end [0061] 16 conductor [0062] 18 sheath [0063] 20 connection point [0064] 22 recess [0065] 24 half-cylinder [0066] 26 metal layer [0067] 30 tool [0068] 32 gold particle [0069] 40 niche [0070] 42 lug