Low Noise Microelectrode Array for Extracellular Record

An integrated approach to probing the electrophysiology of neural tissue in the normal or pathological state requires multiple electrodes for simultaneous recording of neural activity at different levels in tissue. Typical microelectrodes for single unit recording have high impedances due to the extremely small electrode interface which introduces interference from background noise. This proposal seeks to develop arrays of dimensionally small microelectrodes with high real surface area, high capacitance, and low impedance to minimize unwanted noise in neural recordings. The proposed approach to array fabrication provides an uncomplicated fabricated method, a renewable surface, and the potential for large numbers of sites in a single penetrating probe. The electrode interface will be the cross-sectional exposure of an Ir oxide film sandwiched between two insulators, thus producing a very narrow band electrode. Phase I tasks will determine the optimum film deposition conditions which will produce band microelectrodes with low impedance, low noise, and stable dc potential. All Phase I testing will be done under in vitro conditions but in a simulated in vivo environment. Demonstration of the feasibility of this approach will lead to a Phase II program to develop arrays of recording microelectrodes and demonstration of in vivo neural recording.