Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Functional Enhancement and Characterization of an Electrophysiological Mapping Electrode Probe with Carbonic, Directional Macrocontacts

Radu Cristian Popa
* ORCID logo ,
Cosmin Andrei Serban
,
Andrei Barborica
,
Ana-Maria Zagrean
ORCID logo ,
Octavian Buiu
,
Niculae Dumbravescu
,
Alexandru Catalin Paslaru
ORCID logo ,
Cosmin Obreja
,
Cristina Pachiu
,
Marius Stoian
,
Catalin Marculescu
ORCID logo ,
Antonio Radoi
ORCID logo ,
Silviu Vulpe
,
Marian Ion
ORCID logo
Version 1 : Received: 26 July 2023 / Approved: 27 July 2023 / Online: 28 July 2023 (03:21:45 CEST)

A peer-reviewed article of this Preprint also exists.

Popa, R.C.; Serban, C.-A.; Barborica, A.; Zagrean, A.-M.; Buiu, O.; Dumbravescu, N.; Paslaru, A.-C.; Obreja, C.; Pachiu, C.; Stoian, M.; Marculescu, C.; Radoi, A.; Vulpe, S.; Ion, M. Functional Enhancement and Characterization of an Electrophysiological Mapping Electrode Probe with Carbonic, Directional Macrocontacts. Sensors 2023, 23, 7497. Popa, R.C.; Serban, C.-A.; Barborica, A.; Zagrean, A.-M.; Buiu, O.; Dumbravescu, N.; Paslaru, A.-C.; Obreja, C.; Pachiu, C.; Stoian, M.; Marculescu, C.; Radoi, A.; Vulpe, S.; Ion, M. Functional Enhancement and Characterization of an Electrophysiological Mapping Electrode Probe with Carbonic, Directional Macrocontacts. Sensors 2023, 23, 7497.

Abstract

Electrophysiological mapping (EM) using acute electrode probes is a common procedure performed during functional neurosurgery. Due to their constructive specificities, the EM probes are lagging in innovative enhancements. This work addressed complementing a clinically employed EM probe with carbonic and circumferentially segmented macrocontacts that are operable both for neurophysiological sensing ("recording") of local field potentials (LFP), and for test stimulation. The paper illustrates in-depth the development, that is based on direct writing of functional materials. The unconventional fabrication processes were optimized on planar geometry and then transferred to the cylindrically thin probe body. We report and discuss on the constructive concept and architecture of the probe, characteristics of the electrochemical interface deduced from voltammetry and chronopotentiometry, and the results of in vitro and in vivo recording and pulse stimulation tests. Two and three directional macrocontacts were added on probes having shanks of 550 and 770 m diameters and 10-23 cm lengths. The graphitic material presents a ~2.7 V-wide, almost symmetric water electrolysis window, and an ultra-capacitive charge transfer. When tested with 150 s biphasic current pulses, the interfacial polarization stayed safely away from the water window for pulse amplitudes up to 9 mA (135 C/cm2). The in vivo experiments on adult rat models confirmed the high-quality sensing of LFPs. Additionally, the in vivo-prevailing increase of the electrode impedance and overpotential are discussed and modeled by an ionic mobility-reducing spongiform structure; this restricted diffusion model gives new applicative insight into the in vivo-uprisen stimulation overpotential.

Keywords

electrophysiological guidance electrode; directional sensing (recording) and stimulation; carbonic macrocontacts; local field potentials; charge injection capacity; pulse chronopotentiometry; in vivo; overpotential

Subject

Engineering, Bioengineering

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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