Implantable cable having securely attached ring contacts and methods of manufacturing the same

In one embodiment, a method of manufacturing a biological electrical stimulus cable assembly, comprises: providing a cable portion including a plurality of first conductive wires; removing a first portion of the insulative material from a surface along the length of the insulative material at a first location to expose only one of the first conductive wires; electrically connecting a second conductive wire to the first exposed wire surface; wrapping the second conductive wire about the cable portion a plurality of times around the cable portion such that the second conductive wire forms a substantially continuous band; electrically connecting a second end of the second conductive wire to a conductive surface; and providing an electrode over the band formed by the second conductive wire, wherein the band formed by the second conductive wire extends along at least a majority of the length of the electrode.

BACKGROUND

Cables that are designed to be implanted in a patient, typically for pain management or other neurological stimulation, are generally fitted with a series of ring contacts. A ring contact, which circumscribes the cable, makes contact with the desired location inside the patient's body, regardless of the orientation of the cable.

The presently used technique for attaching the ring connectors is somewhat cumbersome. Typically, each individual wire is stripped and a ring fixture is crimped onto it. This operation requires a fair amount of manual labor, requiring fine coordination, and is, therefore, quite expensive.

SUMMARY

In one embodiment, a method of manufacturing a biological electrical stimulus cable assembly, comprises: providing a cable portion including a plurality of first conductive wires, wherein the plurality of first conductive wires are enclosed within the insulative material that forms a body of the cable portion; removing a first portion of the insulative material from a surface along the length of the insulative material at a first location to expose only one of the first conductive wires thereby creating a first exposed wire surface, wherein the removing the first portion is performed on the cable portion after the plurality of first conductive wires are disposed within the insulative material of the body of the cable portion; electrically connecting a first end of a second conductive wire to the first exposed wire surface; wrapping the second conductive wire about the cable portion, wherein the wrapping causes the second conductive wire to be wrapped a plurality of times around the cable portion such that the second conductive wire forms a substantially continuous band around the cable portion; electrically connecting a second end of the second conductive wire to a conductive surface; and providing an electrode over the band formed by the second conductive wire, wherein the band formed by the second conductive wire extends along at least a majority of the length of the electrode.

The foregoing has outlined rather broadly certain features and/or technical advantages in order that the detailed description that follows may be better understood. Additional features and/or advantages will be described hereinafter which form the subject of the claims. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the appended claims. The novel features, both as to organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the appended claims.

DETAILED DESCRIPTION

Referring toFIGS. 1-3, a preferred method of practicing the invention begins with a cable portion10having a set of first conductive wires12set into a double layered structure of insulative material14about a tube13. In an alternative preferred embodiment, a wire is placed in the center of cable portion10to impart longitudinal strength to cable portion10.

A laser is used to ablate an aperture15(FIG. 2) through insulative material14and a second conductive wire16is threaded through this aperture15into contact with a first conductive wire12, to which it is laser welded or otherwise attached. A drop of epoxy may then be added into aperture15, to better secure wire16. Wire16is then wrapped about cable portion10and welded to a conductive ring18(FIG. 3) that has been placed about cable portion10. The result is a connection between first conductive wire12and conductive ring18that is both electrically and structurally robust. In a particular preferred embodiment, shown inFIG. 4, an additional aperture20is formed through insulative material14, spaced apart longitudinally from aperture15. Wire16is then attached to wire12by way of aperture15, wound about cable portion10and then attached again to wire12through aperture20. This provides a particularly robust attachment for wire16and provides a good amount of surface area to form an excellent electrical connection with ring18, which is threaded directly radially over wire16. In an alternative preferred embodiment, wire16is wrapped about cable portion10a single time only, as it stretches from aperture15to aperture20. In another alternative embodiment, wire16forms a circumscribing electrode on its own, without the presence of a ring18(i.e.,FIG. 4shows the final product).

In an alternative preferred embodiment, a conductive ring18is constructed of conductive material directly on the cable portion10. In an additional alternative preferred embodiment, a partial ring (for example, one that extends through three-quarters of a circle) is used. In one preferred embodiment, cable portion10has a diameter of 500 microns, wires12are 100 microns thick, wire16is 75 microns thick and ring18is 50 microns thick and 3,000 microns wide.

Although a frequency multiplied ND:YAG laser is the preferred device for removing insulative material14, the pulse lengths available from this type of laser are typically not lengthy enough to facilitate laser welding. As a result, for the welding portion of the above described task, the preferred tool is a ND:YAG that is not frequency multiplied or a CO2laser.

To help hold each ring18in place, the cable portion10may be over molded after rings18have been attached. In this operation, the cable portion10is encased in a polymer resin, which does not cover the outer surfaces of rings18. In this manner rings18may be affirmatively retained and not permitted to slide longitudinally.

In some embodiments, ring18is placed radially over wire16, while in a different preferred embodiment, wire16abuts ring18longitudinally.