Comparison of the electrochemical properties of smooth and porous TiN electrode coatings in rats

Eight smooth and 8 porous titanium nitride (TiN) coated electrodes were implanted in 8 rats. Before implantation, voltage transients (VTs), cyclic voltammograms (CVs) and impedance spectra were recorded in phosphate buffered saline (PBS). During the implanted period, these measurements were repeated weekly. The VTs and CVs at high sweep rates of the porous electrodes were more affected by implantation as compared to the smooth electrodes. The charge injection (Q_inj) and charge storage capacity (CSC) of both electrode types decreased during the first 3 weeks after implantation. This indicates that protein adhesion directly after implantation presents a diffusion limitation for the porous electrodes only, while cell adhesion limits diffusion for both smooth and porous electrodes.