Design and implementation of two-dimensional neural interfaces

Two-dimensional microelectrode arrays have been developed to serve as a direct man-machine neural interface wherein each microelectrode will be capable of action potential detection and stimulation. Passive arrays for determination of microelectrode circuit parameters have been designed and fabricated. The development of the circuit models, process steps and testing methods for postprocessing commercially fabricated CMOS devices into directly implantable microelectrode arrays are the desired end results. In parallel, the development of the required circuit designs for scanning and interfacing to the microelectrodes is being carried out. A 1024-site actively scanned array has been implemented using a standard double-metal 3- mu m polysilicon-gate CMOS process. The ultimate goal of the circuit design process is to achieve a density of microelectrodes comparable to the cross-sectional density of axons in peripheral nerves (approximately 2000 per mm/sup 2/).<>