Edge-effect electrodes for inducing spatially controlled distributions of electrical potentials in volume conductive media

An electrode system for providing electrical stimulation to a desired location within volume-conductive media, comprising:

• an implantable electrode array comprising a plurality of closely spaced metal contacts separated by less than about 10 mm, at least one of said metal contacts being coated with a coating of activated iridium, each metal contact having means for making electrical contact therewith, and each having a sufficient area to not function as a point source;
• anti-corrosion means for preventing each of said metal contacts from corroding in the presence of a high current density at an edge of said metal contacts;
• and
• means for inducing an electric field between a pair of said plurality of metal contacts so that, when volume-conductive media is inserted therebetween, a high density electrical current flows from a portion of an edge of one of said metal contacts of said pair through the volume-conductive media to the other metal contact of said pair, whereby an edge-effect electrical current flow is induced between the pair of metal contacts.

An implantable electrode array comprising:

• an elongate, non-conductive, flexible, resilient carrier formed into a desired shape;
• a multiplicity of spaced-apart small electrodes formed on said carrier, each having a separate wire connected thereto, the wires from all of said small electrodes passing through said carrier to a proximal end thereof whereat electrical contact may be selectively made with each of said wires;
• and
• an elongate common electrode formed along one side of said carrier, said elongate common electrode having an additional wire connected thereto that passes through said carrier to its proximal end whereat electrical contact may be made therewith, said elongate common electrode having folds to provide a plurality of high points and low points along its length between adjacent ones of said small electrodes;
• whereby an electrical potential may be selectively applied between a selected one of said multiplicity of small electrodes and said common electrode by selectively applying the electrical potential to appropriate wires at the proximal end of said carrier, said electrical potential creating a spatial distribution of electrical fields that, when the electrode array is inserted into a volume-conductive media, causes an electrical stimulating current to flow through the media between the selected small electrode and a small area of the elongate common electrode adjacent the selected small electrode, thereby effectively providing bipolar stimulation between the selected small electrode and the small area of the elongate common electrode adjacent thereto, and
• whereby a multiplicity of bipolar electrode sites may be provided through selective application of a voltage potential to appropriate ones of said wires.

An electrode system for providing electrical stimulation to a desired location within volume-conductive media, comprising:

• an implantable electrode array comprising
• at least one elongate metal contact,
• a plurality of smaller metal contacts, and
• a non-conductive carrier that holds said elongate metal contact in a fixed spaced-apart relationship relative to the plurality of smaller metal contacts, said non-conductive carrier having a spiral shape having an inside edge, and
• wherein corresponding portions of each of the plurality of smaller metal contacts are approximately equidistant from an edge of said elongate metal contact, and further
• wherein said elongate metal contact lies on the inside edge of the spiral-shaped non-conductive carrier;
• means for inducing an electric field between a pair of metal contacts that includes said at least one elongate metal contact and a selected one of the plurality of smaller metal contacts so that, when volume-conductive media is inserted between the pair of metal contacts, a high density electrical current flows from a portion of an edge of said elongate metal contact through the volume-conductive media to the smaller metal contact of said pair, whereby an edge-effect electrical current flow is induced between the pair of metal contacts;
• and
• means for controlling the induced electric field so that the edge-effect electrical current flow is directed to a desired region within the volume-conductive media, said means for controlling the induced electric field comprising means for selectively energizing a respective pair of said metal contacts with an electric potential for a specified pulsed time period in a defined sequence, with only one pair of metal contacts being energized with an electric potential at any given instant of time, and wherein the direction of the current flow into a desired region of the volume-conductive media is a function of the pulsed time period of the electric potential applied to a given pair of metal contacts and the defined sequence in which the respective pairs of metal contacts are energized, whereby edge-effect electrical currents are used beneficially in a closely spaced bipolar metal contact configuration.

An implantable electrode array comprising:

• a elongate, non-conductive, flexible, resilient carrier formed into a desired shape;
• a multiplicity of spaced-apart small electrodes formed on said carrier, each having a separate wire connected thereto, the wires from all of said small electrodes passing through said carrier to a proximal end thereof whereat electrical contact may be selectively made with each of said wires;
• and
• an elongate common electrode formed along one side of said carrier, said elongate common electrode having spring-like properties that impart the desired shape to said resilient carrier, said elongate common electrode further having an additional wire connected thereto that passes through said carrier to its proximal end whereat electrical contact may be made therewith;
• whereby an electrical potential may be selectively applied between a selected one of said multiplicity of small electrodes and said common electrode by selectively applying the electrical potential to appropriate wires at the proximal end of said carrier, said electrical potential creating a spatial distribution of electrical fields that, when the electrode array is inserted into a volume-conductive media, causes an electrical stimulating current to flow through the media between the selected small electrode and a small area of the elongate common electrode adjacent the selected small electrode, thereby effectively providing bipolar stimulation between the selected small electrode and the small area of the elongate common electrode adjacent thereto, and
• whereby a multiplicity of bipolar electrode sites may be provided through selective application of a voltage potential to appropriate ones of said wires.

An implantable cochlear electrode array comprising:

• a elongate, non-conductive, flexible, resilient spiral-shaped carrier formed to fit within a cochlea of a human ear;
• a multiplicity of spaced-apart small electrodes formed on said carrier, each having a separate wire connected thereto, the wires from all of said small electrodes passing through said carrier to a proximal end thereof whereat electrical contact may be selectively made with each of said wires, and wherein said multiplicity of small electrodes are spaced apart a distance d on said carrier, where d is less than about 1.2 mm;
• and
• an elongate common electrode formed along one side of said carrier, said elongate common electrode having an additional wire connected thereto that passes through said carrier to its proximal end whereat electrical contact may be made therewith;
• whereby an electrical potential may be selectively applied between a selected one of said multiplicity of small electrodes and said common electrode by selectively applying the electrical potential to appropriate wires at the proximal end of said carrier, said electrical potential creating a spatial distribution of electrical fields that, when the electrode array is inserted into a volume-conductive media, causes an electrical stimulating current to flow through the media between the selected small electrode and a small area of the elongate common electrode adjacent the selected small electrode, thereby effectively providing bipolar stimulation between the selected small electrode and the small area of the elongate common electrode adjacent thereto, and
• whereby a multiplicity of bipolar electrode sites may be provided through selective application of a voltage potential to appropriate ones of said wires.