A bulk micromachined silicon neural probe with nanoporous platinum electrode for low impedance recording

In this research, a bulk micromachined silicon neural probe with electroplated nanoporous Pt (NPt) electrodes was newly designed, fabricated, and characterized to reduce the interfacial impedance of microelectrodes which are highly desirable for neural signal recording and stimulation. One of the most important requirements in the electro-chemical neural probes is to reduce the interfacial impedance of microelectrodes, because the neural signals usually have very small amplitude and the increased impedance can cause the charge transfer capability of microelectrodes to decrease. The highly roughened NPt film was electroplated on top of circular shaped gold electrode (Diameter: 2 μm) formed on the tip of silicon neural probe. The roughen NPt surface could dramatically reduce the interface impedance of microelectrodes of neural probe. The fabricated neural probe exhibited extremely low impedance of 0.029 Ωcm² and specific capacitance of 4.6 mFcm^-2 at 1.2 kHz, respectively.