Investigation of long-term electrical degradation in neural recording and stimulation microelectrode arrays

As neural interfaces become more commonplace, understanding the long-term reliability of implantable neural recording and stimulation electrode arrays is becoming of great importance. The electrical connection of array electrodes to the surrounding neural tissue and fluid should be limited to the exposed electrode tips, with all other leakage currents minimized. It is the goal of this study to identify and quantify electrical leakage within commercially available implantable microelectrode arrays. Both short term and accelerated stress tests were performed on entire arrays and on individual electrode pins. Test results indicate that leakage current pathways develop upon submersion of the electrodes in biological fluid and micrograph photos taken of the electrode shafts show extensive defect regions that may indicate the locations of such pathways.