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Microélectrodes nanocomposites implantables couplant enregistrement/stimulation neurale et détection électrochimique de neurotransmetteurs

Valentin Saunier 1
1 LAAS-MEMS - Équipe Microsystèmes électromécaniques
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : Electrophysiology is the physiology field that aims at recording the electrical activity of biological tissues. Using microelectrodes in the brain, electrophysiology helped make crucial advancements in the understanding of major neurological mechanisms like memory, language, learning by recording the brain electrical signals. Through these advances, it promised and helped develop treatments and therapeutic devices to cure the major neurological diseases like Parkinson’s, Alzheimer’s or epilepsy. However, recently the need for other sources of information to combine with electrophysiological recordings has raised, as the research and therapeutic approaches over-relying on these recordings did mostly lead to dead-ends. As the brain electrical activity is molecularly supported by a class of molecules called neurotransmitters, their detection in real-time is proposed as a high-potential complementary brain study technique to integrate along with electrophysiological recordings during neural interfacing. During this PhD, we developed a new generation of nanocomposite microelectrodes made of both PEDOT and oxidized carbon nanofibers to meet this combined integration. These electrodes displayed a key characteristic combination in-vitro, with low impedance, high charge injection limit, making them promising candidates for bidirectional electrophysiology, while being capable to detect dopamine (one key neurotransmitter) using two complementary techniques, chronoamperometry and fast-scan cyclic voltammetry. Moreover, these electrodes keep a sufficiently low spatial profile to interface with single cells, making them promising candidates for multifunctional neural interfacing, adding neurochemical detection to electrical recordings. Integrated on flexible implants, these electrodes were first tested in-vivo in brain slices as recording and stimulating electrodes (realizing bidirectional electrophysiology). They showed high performances, being capable to record brain electrical signals on a wider frequency range than standard microelectrodes, with a higher Signal to Noise Ratio (SNR). They also allowed to electrically stimulate brain slices tissues, generating measurable outputs with low inputs compared to standard electrodes. In conclusion, the modified electrodes developed in this thesis showed promising properties for multifunctional neural interfacing at a single cell level, enabling the coupling between electrophysiological recording and electrical stimulation of tissues in-vivo, while also being capable of neurotransmitter electrodetection in-vitro. Through these properties, they constitute meaningful candidates for long-term simultaneous recording of the brain electrical and neurochemical activities for research and therapeutic applications.
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https://hal.laas.fr/tel-03230046
Contributor : Laas Hal-Laas <>
Submitted on : Wednesday, May 19, 2021 - 2:34:31 PM
Last modification on : Wednesday, June 9, 2021 - 10:00:33 AM
Long-term archiving on: : Friday, August 20, 2021 - 6:36:53 PM

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Valentin Saunier. Microélectrodes nanocomposites implantables couplant enregistrement/stimulation neurale et détection électrochimique de neurotransmetteurs. Micro et nanotechnologies/Microélectronique. Université Toulouse 3 Paul Sabatier, 2021. Français. ⟨tel-03230046⟩

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