Fabrication of a porous anodic alumina membrane

With the aim of developing a process for surface enlargement on an electrode for measuring brain activity attempts have been made to fabricate a porous anodic alumina membrane directly on the electrode. The porous membrane was intended to be used as scaffold for deposition of an electrically conducting polymer on the electrode surface. A silicon wafer with gold electrodes was the base onto which the aluminum used in the anodization process was evaporated. The resulting device is a simplified model of an actual brain implant, and was anodized potentiostatically in oxalic acid solution while the current was recorded. The anodizing potential was set to 1 V to prevent damage to the electrodes. The experiments have been evaluated using light and scanning electron microscopy, SEM. Some electrodes expressed changes in color after anodization but the surface of aluminum seemed to be unaffected and no signs of pore formation were seen. SEM investigations showed that the initial aluminum layer had an inhomogeneous structure and it was observed that aluminum seemed to loosen from the electrode and drift away after long-term acid exposure. Electrodes where this had happened seemed to be affected by anodization and expressed changes in surface structure.