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.

Glassy Carbon Electrocorticography Electrodes on Ultra-Thin and Finger-Like Polyimide Substrate: Performance Evaluation Based on Different Electrode Diameters

“…Depending on the type of damage and on the targeted anatomical area, design and location of the implants changes (Figure 1) and can be tailored for reaching the best compromise between invasiveness and function restoration. Although they are considered minimally invasive when compared to penetrating devices, microelectrode arrays (MEAs) for ECoG still elicit foreign-body response and glial scar formation that can—in the long term—isolate them from the nerve cells [3,4,5]. One way to minimize their encapsulation is to reduce the substrate footprint on the brain surface and promote the diffusion of soluble factors through the devices by optimizing their design [6,7].…”

Flexible Bioelectronic Devices Based on Micropatterned Monolithic Carbon Fiber Mats

“…Various sp 2 ‐rich carbon materials are cytocompatible, corrosion resistant, electrically conductive, and electrochemically stable . Carbon‐based ECoG electrodes have been successfully tested as multimodal electrode material utilizing graphene flakes, carbon nanotubes (CNTs), glassy carbon, and carbon fibers (CFs) . Recently there has been a lot of progress in the field of graphene‐based transparent flexible devices .…”