Wafer-scale processed, low impedance, neural arrays with varying length microelectrodes

Advances in silicon micromachining have lead to development of sophisticated neural interfaces such as the Utah slant electrode array (USEA). The unique architecture of the USEA comprises of electrodes which increase in length in one direction, while being constant in length in the other. When implanted into a peripheral nerve, the tips of the electrodes penetrate nerve fascicles, and are close to discrete populations of nerve fibers. Although the USEA has been widely used in neural prosthesis the current processes used to fabricate USEA impose limitations in the tolerances of the electrode array geometry. This paper presents a wafer scale fabrication method for USEA which offers high precision and control in electrode geometry and their electrical characteristics.