In-Vivo Characterization of Glassy Carbon µ-Electrodes and Histological Analysis of Brain Tissue after Chronic Implants

Abstract

For neural applications, materials that combine excellent electromechanical properties with long-term performance capabilities are ideal. Good electrodes should be able to not only adapt to eventual physiological changes in the body, but also perform without damaging the host tissue. The combination of these characteristics is difficult to accomplish, since the ability of a material to undergo changes is often accompanied by the formation of reaction products that might interact with the surrounding tissue. Glassy carbon is a biocompatible and electrochemically inert material with tunable mechanical and electrical properties, high charge injection capacity and great resistance to corrosion. These merits motivate the use of such material for neural applications, and in particular for the realization of electrocorticography (ECoG) microelectrodes that can electrically sense and stimulate brain activity. We demonstrate that glassy carbon electrodes do not trigger specific immune responses and are able to maintain stable impedance after several weeks of implantation.