| abstract |
A multicontact electrode array suitable for implantation in living tissue includes a distal end having multiple spaced-apart ring contacts or a pattern of spaced-apart electrode contacts carried on a flexible carrier. Each electrode contact is resistance welded to a respective wire that is wound helically inside a silicon tube. The center of the helix defines a lumen wherein a positioning stylet, or other suitable positioning tool, may be removably inserted when the electrode array is implanted. The electrode array is made using a method that includes, as an initial step, winding lead wires around a suitable mandrel forming a helix configuration. Next, a non-conductive silicone tube jacket is placed around the wound wires, exposing the distal lead ends of the wires at a distal end of the tube. A welding process is then used to bond each wire tip to a corresponding metal electrode contact which has been preassembled by resistance welding to a metal foil structural carrier. The electrode array, including the metal foil structural carrier, is then formed into a tube by drawing it through a die. The excess foil material at the distal tip is then trimmed and a heat-shrink tube is placed around the assembled foil tube to prevent leakage of the polymer filler material through the joining longitudinal line of the carrier. Next, the foil tube is injected with a polymer filler material to void any gaps between the lead wires and contacts. To avoid filling the central lumen with the polymer filler material, a central core or stylet is temporarily placed inside the lumen. The heat-shrink tube is then mechanically removed. The fabrication method is finalized by inserting the preassembled electrode array into a hot acid mixture, which etches away the metal foil carrier, exposing the contacts at the surface of a distal end of the electrode array. |