Ultra-Capacitive Carbon Neural Probe Allows Simultaneous Long-Term Electrical Stimulations and High-Resolution Neurotransmitter Detection

This all glassy carbon neural probe comes in two forms for monitoring different brain areas. Electrodes are embedded in a flat, flexible substrate for electrocorticography (ECoG) monitoring on the surface of the brain (lower left, magnification of electrode array used for electrical stimulation, upper left) and connected to a thin needle for intracortical readings deeper within the brain (upper right, magnification of electrode array used for dopamine detection, lower right).


Authors: Surabhi Nimbalkar, Elisa Castagnola, Arvind Balasubramani, Alice Scarpellini, Soshi Samejima, Abed Khorasani, Adrien Boissenin, Sanitta Thongpang, Chet Moritz and Sam Kassegne

Publication: Nature Scientific Reports

Date: May 3, 2018

DOI: 10.1038/s41598-018-25198-x

We present a new class of carbon-based neural probes that consist of homogeneous glassy carbon (GC) microelectrodes, interconnects and bump pads. These electrodes have purely capacitive behavior with exceptionally high charge storage capacity (CSC) and are capable of sustaining more than 3.5 billion cycles of bi-phasic pulses at charge density of 0.25 mC/cm2. These probes enable both high SNR (>16) electrical signal recording and remarkably high-resolution real-time neurotransmitter detection, on the same platform. Leveraging a new 2-step, double-sided pattern transfer method for GC structures, these probes allow extended long-term electrical stimulation with no electrode material corrosion. Cross-section characterization through FIB and SEM imaging demonstrate strong attachment enabled by hydroxyl and carbonyl covalent bonds between GC microstructures and top insulating and bottom substrate layers. Extensive in-vivo and in-vitro tests confirmed: (i) high SNR (>16) recordings, (ii) highest reported CSC for non-coated neural probe (61.4 ± 6.9 mC/cm2), (iii) high-resolution dopamine detection (10 nM level - one of the lowest reported so far), (iv) recording of both electrical and electrochemical signals, and (v) no failure after 3.5 billion cycles of pulses. Therefore, these probes offer a compelling multi-modal platform for long-term applications of neural probe technology in both experimental and clinical neuroscience.

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Thursday, May 3, 2018