Progress towards biocompatible intracortical microelectrodes for neural interfacing applications

Mehdi Jorfi, John L Skousen, Christoph Weder, Jeffrey R Capadona
2014 Journal of Neural Engineering  
To ensure long-term consistent neural recordings, next-generation intracortical microelectrodes are being developed with an increased emphasis on reducing the neuro-inflammatory response. The increased emphasis stems from the improved understanding of the multifaceted role that inflammation may play in disrupting both biologic and abiologic components of the overall neural interface circuit. To combat neuro-inflammation and improve recording quality, the field is actively progressing from
more » ... ional inorganic materials towards approaches that either minimizes the microelectrode footprint or that incorporate compliant materials, bioactive molecules, conducting polymers or nanomaterials. However, the immune-privileged cortical tissue introduces an added complexity compared to other biomedical applications that remains to be fully understood. This review provides a comprehensive reflection on the current understanding of the key failure modes that may impact intracortical microelectrode performance. In addition, a detailed overview of the current status of various materials-based approaches that have gained interest for neural interfacing applications is presented, and key challenges that remain to be overcome are discussed. Finally, we present our vision on the future directions of materials-based treatments to improve intracortical microelectrodes for neural interfacing. Since the first generation, significant development efforts have been devoted to improve the performance of the UEA. For example, to improve charge transfer, Pt/Ti/W/Pt, and then subsequently sputtered iridium oxide (SIROF), have been used instead of the original gold or platinum contacts on the terminal recording sites. (45) Furthermore, conformal Parylene-C coatings have been applied through chemical vapor deposition to provide additional insulation to the electrode tines and protect the underlying dielectrics from dissolution. (46) Electrical isolation of individual channels has been further enhanced by incorporating a glass dielectric between individual bond pads on the backside of the wafer. (47) Jorfi et al.
doi:10.1088/1741-2560/12/1/011001 pmid:25460808 pmcid:PMC4428498 fatcat:yk3auje62jhvzhyvnpq7yrd5si