This work describes the microfabrication processes in creating a flexible polyimide-based implantable neural probe for future integration with a CMOS-based closed-loop system. An equivalent circuit model for the fabricated electrodes is produced from electrochemical impedance spectroscopy measurements. The average impedance of the two electrodes at 1kHz is 80.79±13.94 Ω, thanks to the large surface area exposed to the electrolyte. In each case, the charge transfer resistance was less than 20 kΩ, with a double layer capacitance lower than 30 µF. At high frequencies dominated by the solution resistance, the Nyquist plot matches the expected shape for a bare platinum electrode.