Titanium nitride pacing electrodes with high surface-to-area ratios

High surface-to-area ratio TiN coatings for cardiac pacing electrodes were obtained by arc ion plating. The substrate bias potential and the processing time were critical for obtaining coatings with the appropriate topography. Dark high surface-to-area ratio TiN deposits were found to be near stoichiometric TiN, with a columnar growth of strongly oriented crystals in the (1 1 1) direction with an open structure. The difference in color observed with the traditional golden TiN films have been attributed to the topography of the coatings. Pacing impedance values were found to decrease markedly with the most favorable dark TiN coatings achieving full electrical depolarization of the electrode-fluid interface. Ion nitriding of Ti substrates did not result in favorable results for the conditions tested.