Connection of electrodes to wires coiled on a core

1. An apparatus, comprising:

a cable comprising a plurality of insulated wires coiled around a central core in a close-packed configuration, each of the insulated wires having a respective conductor surrounded by insulation;

an access channel to at least one conductor of at least one insulated wire in the cable, formed by removing a portion of the insulation from the at least one insulated wire while the cable remains coiled on the central core; and

a ring electrode having an inner surface connected by a deformed solder ball to the at least one conductor of the at least one insulated wire via the respective access channel, the connection between the inner surface of the ring electrode and the at least one conductor being formed by heating the ring electrode while pressing the ring electrode onto an undeformed solder ball, wherein the undeformed solder ball is positioned prior to deformation in proximity to an entrance of the access channel such that the undeformed solder ball is not electrically coupled with the conductor of the at least one insulated wire, wherein the heating and pressing melt and deform the undeformed solder ball such that the solder ball subsequently penetrates the access channel forming a bridge and when cooled, the deformed solder ball bridge connects and electrically couples the ring electrode to the conductor of the at least one insulated wire via the access channel.

2. The apparatus according to claim 1 further comprising glue, applied over the access channel, that holds the undeformed solder ball in place.

3. The apparatus according to claim 1 , wherein the electrode completely encircles the cable.

4. The apparatus according to claim 1 , wherein the electrode partially encircles the cable.

5. The apparatus according to claim 1 , wherein the wires are coiled single-handedly around the central core.

6. The apparatus according to claim 1 , wherein the cable comprises a first group of the wires coiled left-handedly around the central core, and a second group of the wires coiled right-handedly around the central core.

7. A method for attaching an electrode to cable, comprising:

providing the cable having a plurality of insulated wires coiled around a central core in a close-packed configuration, each of the insulated wires having a respective conductor surrounded by insulation;

removing a portion of the insulation from at least one of the insulated wires in the cable so as to provide an access channel to the conductor of the at least one insulated wire while the cable remains coiled on the central core;

positioning an undeformed solder ball in proximity to an entrance of the access channel such that the undeformed solder ball is not electrically coupled with the conductor of the at least one insulated wire;

positioning a ring electrode in contact with the undeformed solder ball; and

heating the ring electrode while pressing the ring electrode onto the undeformed solder ball to melt and deform the solder ball such that the solder ball subsequently penetrates the access channel forming a bridge and when cooled, the deformed solder ball bridge connects and electrically couples an inner surface of the ring electrode to the conductor of the at least one insulated wire via the access channel.

8. The method according to claim 7 , wherein positioning the undeformed solder ball comprises applying glue over the access channel, and holding the undeformed solder ball in place with the glue.

9. The method according to claim 7 , wherein the electrode completely encircles the cable.

10. The method according to claim 7 , wherein the electrode partially encircles the cabling.

11. The method according to claim 7 , wherein the wires are coiled single-handedly around the central core.

12. The method according to claim 7 , wherein the cable comprises a first group of the wires coiled left-handedly around the central core, and a second group of the wires coiled right-handedly around the central core.