Soft MXene Filament Microelectrodes for High-Resolution, Localized Detection of Neural Transmitters and Electrical Signals

The development of soft neural interfaces opens opportunities for long-term studying and modulating brain functions and diseases with fewer side effects by minimizing the mechanical mismatch between artificial devices and soft tissues. However, few designs have enabled both electrical and chemical sensing – necessary for capturing the diverse neural signals <i>in vivo</i> – as simultaneous high conductivity and redox surfaces are required for such multifunctional electrodes. Here we report a novel method leveraging the unique combinations of electrical conductivity, functional surfaces, and solution processibility of MXenes, an emerging class of 2D nanomaterials, to produce a thin conformal MXene coating on nylon filaments (30-300 µm in diameter) at a fast speed (up to 15 mm/s). The highly aligned MXene coatings provide the microelectrodes with an electrical impedance as low as 3Ω at 1kHz. In addition, the MXene coating provides ample redox surfaces for the detection of neural transmitters such as dopamine and 5-hydroxytryptamine. These MXene filament microelectrodes offer a robust, miniaturized platform for the monitor and stimulation of neural activities at the cellular level, facilitating a greater understanding of health and disease.