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

Abstract

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.

Multifunctional Flexible Biointerfaces for Simultaneous Colocalized Optophysiology and Electrophysiology

“…The EIS results are further fit to an equivalent circuit model [ 30,39,40 ] (Figure S6, Supporting Information) to better understand the electrochemical characteristics of the electrodes. The model consists of a constant phase element ( Z CPE ) in parallel with charge transfer resistance ( R CT ), a Warburg impedance ( Z W ), and the solution resistance ( R S ) in series with all other components.…”

Frontiers in electrochemical sensors for neurotransmitter detection: towards measuring neurotransmitters as chemical diagnostics for brain disorders

“…100 Nimbalkar et al designed and fabricated a new class of homogeneous glassy carbon neural probes with no adhesion or conducting metal layers, thereby enhancing the lifetime of the probe for long periods of electrical stimulation (for deep brain stimulation, for example). 129 Interestingly, the same probe materials were capable of stimulating in addition to performing neurochemical measurements. 129 Another hindrance to using traditional FSCV carbon ber probes for chronic measurements is the size of the probe sha, which induced inammatory responses.…”

“…129 Interestingly, the same probe materials were capable of stimulating in addition to performing neurochemical measurements. 129 Another hindrance to using traditional FSCV carbon ber probes for chronic measurements is the size of the probe sha, which induced inammatory responses. While the probe tip was on the order of 5-7 mm, the probe sha can be as large as 100 mm.…”

Flexible Bioelectronic Devices Based on Micropatterned Monolithic Carbon Fiber Mats

“…In the recent past, carbon has gained considerable attention as a neural electrode material owing to its inertness and biocompatibility, ability to serve as multimodal platform for recording, stimulation, and neurotransmitter detection . Various sp 2 ‐rich carbon materials are cytocompatible, corrosion resistant, electrically conductive, and electrochemically stable .…”

“…Various sp 2 ‐rich carbon materials are cytocompatible, corrosion resistant, electrically conductive, and electrochemically stable . Carbon‐based ECoG electrodes have been successfully tested as multimodal electrode material utilizing graphene flakes, carbon nanotubes (CNTs), glassy carbon, and carbon fibers (CFs) . Recently there has been a lot of progress in the field of graphene‐based transparent flexible devices .…”