Method of making a cochlear electrode array having current-focusing and tissue-treating features
View Patent ↗A method of making an implantable electrode array, adapted for insertion into a cochlea, includes the steps of: (a) forming electrode contact pieces made from a precious, biocompatible material into a desired shape; (b) attaching the electrode contact pieces to a foil sheet made from a non-toxic but chemically-active metal; (c) connecting a wiring system to the metal contact pieces; (d) molding a flexible polymer carrier around the electrode contact pieces and wiring system while such are held in place by the foil sheet; and (e) etching away the foil sheet, leaving the electrode contact pieces exposed at a surface of the molded polymer carrier. The exposed electrode contacts are made so as to have a shape, geometry, or makeup that aids in controlling the current flow and current density associated with the electrode contact as a function of position on the electrode contact.
1. A method of making an implantable electrode array comprising:
(a) forming electrode contact pieces made from a precious, biocompatible material into a desired shape;
(b) attaching the electrode contact pieces to a foil sheet made from a non-toxic but chemically-active metal,
(c) connecting a wiring system to the metal contact pieces;
(d) molding a flexible polymer carrier around the electrode contact pieces and wiring system while such are held in place by the foil sheet; and
(e) etching away the foil sheet, leaving the electrode contact pieces exposed at a surface of the molded polymer carrier.
2. The method of claim 1 wherein step (a) comprises forming the electrode contact pieces into an oval shape.
3. The method of claim 1 wherein step (a) comprises forming the electrode contact pieces into a star shape.
4. The method of claim 1 further comprising coating the electrode contact pieces exposed at a surface of the molded polymer carrier with a material that controls the surface impedance of the electrode contact piece as a function of location on the contact surface.
5. The method of claim 4 comprising coating each electrode contact piece so that the surface impedance of the contact piece increases as a function of distance from the center of the electrode contact piece.
6. The method of claim 1 further comprising masking an electrode contact piece exposed at a surface of the molded polymer carrier with an insulative mask that prevents conduction at various locations at the surface of the electrode contact piece.
7. The method of claim 1 further comprising coating at least one of the flexible polymer carrier or electrode contact piece with a drug compound selected to diffuse into tissue around the electrode array for the purpose of any one of the following: inhibiting fibrous tissue growth, inhibiting bone growth, promoting healing, preventing neural degeneration, and promoting neural regeneration.
8. The method of claim 7 wherein the step of coating with a drug compound comprises coating at least one of the flexible center or electrode contact piece with a steroid.
9. The method of claim 7 wherein the step of coating with a drug compound comprises coating at least one of the flexible carrier or electrode contact piece with a neuro-trophin.
10. The method of claim 7 wherein step (c) comprises molding the flexible polymer carrier so that the resulting electrode array assumes a naturally curved shape.