Durability of high surface area platinum deposits on microelectrode arrays for acute neural recordings
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The durability of high surface area platinum electrodes during acute intracerebral measurements was investigated. Electrode sites with extremely rough surfaces were realized using electrochemical deposition of platinum onto silicon-based microelectrode arrays from a lead-free platinizing solution. The close to 1000-fold increase in effective surface area lowered impedance, its absolute value at 1 kHz became about 7 and 18 % of the original Pt electrodes in vitro and in vivo, respectively. 24-channel probes were subjected to 12 recording sessions, during which they were implanted into the cerebrum of rats. Our results showed that although on the average the effective surface area of the platinized sites decreased, it remained more than two orders of magnitude higher than the average effective surface area of the original, sputtered thin-film platinum electrodes. Sites with electrochemical deposits proved to be superior, e.g. they provided less thermal and 50 Hz noise, even after 12 penetrations into the intact rat brain.
Useful and motivating discussions with Dr. Tamás Pajkossy are greatly acknowledged. We are grateful to Mrs. Károlyné Payer, Mr. András Strasszner, Mr. Róbert Hodován and Mr. András Lőrincz for their support in the clean room. We also wish to thank Mr. Attila Nagy and Mr. István Réti for their help in chip packaging, also to Mr. Péter Kottra and Mr. István Wosinski for their support in the in vivo experiments. Anita Pongrácz is thankful for the Bolyai János Grant of the HAS. This research was supported by the Hungarian Science Foundation (OTKA K81354), the French-Hungarian ANR-TÉT Neurogen, ANR-TÉT Multisca, TAMOP-4.2.1.B-11/2/KMR-2011-0002 and EU FP7 600925 Neuroseeker grants to István Ulbert.
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