title: First long term in vivo study on subdurally implanted micro-ECoG electrodes, manufactured with a novel laser technology.
abstract: A novel computer aided manufacturing (CAM) method for electrocorticography (ECoG) microelectrodes was developed to be able to manufacture small, high density microelectrode arrays based on laser-structuring medical grade silicone rubber and high purity platinum. With this manufacturing process, we plan to target clinical applications, such as presurgical epilepsy monitoring, functional imaging during cerebral tumor resections and brain-computer interface control in paralysed patients, in the near future. This paper describes the manufacturing, implantation and long-term behaviour of such an electrode array. In detail, we implanted 8-channel electrode arrays subdurally over rat cerebral cortex over a period of up to 25 weeks. Our primary objective was to ascertain the electrode's stability over time, and to analyse the host response in vivo. For this purpose, impedance measurements were carried out at regular intervals over the first 18 weeks of the implantation period. The impedances changed between day 4 and day 7 after implantation, and then remained stable until the end of the implantation period, in accordance with typical behaviour of chronically implanted microelectrodes. A post-mortem histological examination was made to assess the tissue reaction due to the implantation. A mild, chronically granulated inflammation was found in the area of the implant, which was essentially restricted to the leptomeninges. Overall, these findings suggest that the concept of the presented ECoG-electrodes is promising for use in long-term implantations.
authors.affiliation: Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg i. Breisgau, Germany. henle@imtek.de
authors.forename: C
authors.initials: C
authors.lastname: Henle
authors.forename: M
authors.initials: M
authors.lastname: Raab
authors.forename: J G
authors.initials: JG
authors.lastname: Cordeiro
authors.forename: S
authors.initials: S
authors.lastname: Doostkam
authors.forename: A
authors.initials: A
authors.lastname: Schulze-Bonhage
authors.forename: T
authors.initials: T
authors.lastname: Stieglitz
authors.forename: J
authors.initials: J
authors.lastname: Rickert
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D058266:Dielectric Spectroscopy; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004567:Electrodes, Implanted; D055724:Electrophysiological Phenomena; D005260:Female; D007834:Lasers; D008839:Microelectrodes; D008954:Models, Biological; D010984:Platinum / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D013355:Subdural Space; D013997:Time Factors
chemical_list: D004129:Dimethylpolysiloxanes; D010984:Platinum; C013830:baysilon