The Layer 7 Cortical Interface: A Scalable and Minimally Invasive Brain-Computer Interface Platform

Progress toward the development of brain-computer interfaces has signaled the potential to restore, replace, or augment lost or impaired neurological function in a variety of disease states. Existing brain-computer interfaces rely on invasive surgical procedures or brain-penetrating electrodes, which limit addressable applications of the technology and the number of eligible patients. Here we describe a novel approach to constructing a neural interface, comprising conformable thin-film electrode arrays and a minimally invasive surgical delivery system that together facilitate communication with large portions of the cortical surface in bidirectional fashion (enabling both recording and stimulation). We demonstrate the safety and feasibility of rapidly delivering reversible implants containing over 2,000 microelectrodes to multiple functional regions in both hemispheres of the Gottingen minipig brain simultaneously, without requiring a craniotomy, at an effective insertion rate faster than 40 ms per channel, without damaging the cortical surface. We further demonstrate the performance of this system for high-density neural recording, focal cortical stimulation, and accurate neural decoding. Such a system promises to accelerate efforts to better decode and encode neural signals, and to expand the patient population that could benefit from neural interface technology.

Investigation of Effects of Copper, Zinc, and Strontium Doping on Electrochemical Properties of Titania Nanotube Arrays for Neural Interface Applications

Direct interaction with the neuronal cells is a prerequisite to deciphering useful information in understanding the underlying causes of diseases and functional abnormalities in the brain. Precisely fabricated nanoelectrodes provide the capability to interact with the brain in its natural habitat without compromising its functional integrity. Yet, challenges exist in terms of the high cost and complexity of fabrication as well as poor control over the chemical composition and geometries at the nanoscale, all imposed by inherent limitations of current micro/nanofabrication techniques. In this work, we report on electrochemical fabrication and optimization of vertically oriented TiO2 nanotube arrays as nanoelectrodes for neural interface application. The effects of zinc, strontium, and copper doping on the structural, electrochemical, and biocompatibility properties of electrochemically anodized TiO2 nanotube arrays were investigated. It was found that doping can alter the geometric features, i.e., the length, diameter, and wall thickness, of the nanotubes. Among pure and doped samples, the 0.02 M copper-doped TiO2 nanotubes exhibited superior electrochemical properties, with the highest specific storage capacitance of 130 F g−1 and the lowest impedance of 0.295 KΩ. In addition, regeneration of Vero cells and neurons was highly promoted on (0.02 M) Cu-doped TiO2 nanotube arrays, with relatively small tube diameters and more hydrophilicity, compared with the other two types of dopants. Our results suggest that in situ doping is a promising method for the optimization of various structural and compositional properties of electrochemically anodized nanotube arrays and improvement of their functionality as a potential nanoelectrode platform for neural interfacing.