Commercial translation of high-density carbon fiber electrode arrays for multi-modal analysis of neural microcircuits

ABSTRACT The ability to measure and manipulate local brain circuit activity in living, behaving animals is essential to understanding the complexities of brain function and dysfunction. A novel, penetrating high-density carbon fiber electrode array composed of flexible, ultrathin conductive carbon microfibers was recently developed under the BRAIN Initiative to study neural microcircuit dynamics. In contrast to conventional microelectrode arrays, carbon fiber arrays are exceptionally biocompatible and produce minimal glial scarring resulting in exceptional proximity of the recording electrodes to neurons for unprecedented single-unit recording yield with improved electrode stability, high signal-to-noise recording, and high charge injection capacity (CIC) for superior stimulation. In addition, these arrays can be used to measure neurotransmitter or other biological compounds using fast-scan cyclic voltammetry (FSCV). Led by Blackrock Neurotech, a pioneer and industry leader in microelectrode array fabrication, the goal of this Direct-to-Phase II SBIR is to translate the novel laboratory fabricated high-density carbon fiber array (C-CFA) by the Chestek lab at the University of Michigan to a state-of-the-art commercial product (BRN-CFA) to enable broad dissemination of this powerful and versatile neurotechnology across the neuroscience community. Aim 1: Microfabrication and assembly of the BRN-CFA will dramatically improve the microfabrication process for the silicon support shuttles of the carbon fibers in the BRN-CFA by removing occupationally hazardous materials from the fabrication scheme and adopting a modern silicon-on-insulator wafer fabrication process to improve manufacturing safety, efficiency, and reliability. Array assembly and fabrication will occur under Blackrock’s Quality Management System. Aim 2: Performance validation and process transfer to Blackrock Neurotech will assess the optimized BRN-CFA electrical characteristics, robustness, stability, and longevity through in-vitro electrical, electrochemical testing, accelerated aging, and visual inspection. Analyses will be cross-validated against the C-CFA. The validated geometry, fabrication, and assembly processes will be transferred to Blackrock manufacturing to enable robust and reproducible production. Aim 3. In-vivo chronic performance validation of the BRN-CFA will cross-validate the BRN-CFA against the C- CFA in a 6-month in-vivo study in rat cortex to assess insertability and chronic performance of the devices. The successful outcome of this project will be the first commercially available BRN-CFA with exceptional performance for the study of local neural circuit dynamics. By addressing this critical, unmet need, the BRN-CFA product promises to accelerate basic scientific discovery of brain dynamics and the development of next-generation therapies.