NEVEL MICROELECTRODES FOR NEURAL STIMULATION

THE NEXT GENERATION OF ELECTRODES FOR NEURAL PROSTHESES WILLREQUIRE ARRAYS OF MICROELECTRODES FOR HIGHLY SELECTIVE STIMULATION AND MONITORING OF THE STIMULATED ENVIRONMENT. THE GOAL OF THIS PROGRAM IS TO DEVELOP MICROELECTRODE STRUCTURES THAT HAVE GOOD LONG-TERM STABILITY IN BIOLOGICAL ENVIRONMENTS, ARE SIMPLE TO PRODUCE, AND ARE COMPATIBLE WITH A NEW GENERATION OF ELECTROCHEMICALLY REVERSIBLE, HIGH-CHARGE-CAPACITY ELECTRODE MATERIALS SUCH AS IRIDIUM OXIDE. THIS PROJECT WILL DEVELOP MICROBAND ELECTRODES FOR BOTH ACTIVE AND PASSIVE PROSTHETIC FUNCTIONS. THESE ELECTRODES ARE FORMED FROM A THIN FILM OF VACUUM-DEPOSITED METAL SANDWICHED BETWEEN TWO BIOCOMPATIBLE INSULATORS (E.G., SI3N4OR PARYLENE). ELECTRODE AREAS IN THE RANGE OF 10(-5) CM(2) TO 10(-9) CM(2) CAN BE ACHIEVED. EXPERIMENTS IN PHASE I WILL DEMONSTRATE A BAND ULTRAMICROELECTRODE BASED ON IRIDIUM METAL THAT IS ACTIVATEDELECTROCHEMICALLY TO FORM IRIDIUM OXIDE AT THE ELECTRODE/ELECTROLYTE INTERFACE. THESE ELECTRODES WILL CONSTITUTE A NEW LOWER LIMIT IN AREA FOR ACTIVATED IRIDIUM, AND THE PULSED CAPACITY UNDER TYPICAL INTRACORTICAL CONDITIONS WILL BE CHARACTERIZED AND COMPARED TO RESULTS FORMACROSCOPIC STRUCTURES. DEMONSTRATION OF FEASIBILITY OF THE BAND STRUCTURE IN PHASE I WILL LEAD TO PHASE II INVESTIGATIONS OF MULTIELECTRODE ARRAYS OF BAND ELECTRODES OF VARIOUS MATERIALS DESIGNED FOR STIMULATION AND LOCAL SENSING OF THE CHEMICAL ENVIRONMENT OFTHE TISSUE.