Two-Dimensional TiC MXene for High-Resolution Neural Interfaces.

High-resolution neural interfaces are essential tools for studying and modulating neural circuits underlying brain function and disease. Because electrodes are miniaturized to achieve higher spatial resolution and channel count, maintaining low impedance and high signal quality becomes a significant challenge. Nanostructured materials can address this challenge because they combine high electrical conductivity with mechanical flexibility and can interact with biological systems on a molecular scale. Unfortunately, fabricating high-resolution neural interfaces from nanostructured materials is typically expensive and time-consuming and does not scale, which precludes translation beyond the benchtop. Two-dimensional (2D) TiC MXene possesses a combination of remarkably high volumetric capacitance, electrical conductivity, surface functionality, and processability in aqueous dispersions distinct among carbon-based nanomaterials. Here, we present a high-throughput microfabrication process for constructing TiC neuroelectronic devices and demonstrate their superior impedance and in vivo neural recording performance in comparison with standard metal microelectrodes. Specifically, when compared to gold microelectrodes of the same size, TiC electrodes exhibit a 4-fold reduction in interface impedance. Furthermore, intraoperative in vivo recordings from the brains of anesthetized rats at multiple spatial and temporal scales demonstrate that TiC electrodes exhibit lower baseline noise, higher signal-to-noise ratio, and reduced susceptibility to 60 Hz interference than gold electrodes. Finally, in neuronal biocompatibility studies, neurons cultured on TiC are as viable as those in control cultures, and they can adhere, grow axonal processes, and form functional networks. Overall, our results indicate that TiC MXene microelectrodes have the potential to become a powerful platform technology for high-resolution biological interfaces.