Multifunctional Composite Coating-Enhanced Flexible Microelectrodes for Chronic, High-Fidelity Neural Signal Recording

Abstract

Implantable flexible neuroelectrodes are critical for brain-computer interface (BCI) applications. However, conventional flexible electrodes often face challenges such as increased electrochemical impedance upon miniaturization, mechanical mismatch with brain tissue, and implantation-induced damage, all of which compromise long-term signal stability and recording quality. Here, we present a multifunctional surface modification strategy to address these limitations. By integrating polycaprolactone/silk fibroin-methacrylate (PCL-SFMA) nanofibers loaded with anti-inflammatory minocycline hydrochloride (MH), nanostructured poly(3,4-ethylenedioxythiophene) (PEDOT) for impedance reduction, and a bioactive SFMA hydrogel layer for seamless neural integration, we developed a composite-coated flexible microelectrode (Au-PCLSFMA-PEDOT-GEL). Comprehensive in vitro and in vivo evaluations demonstrated that the modified electrode exhibited low impedance, enhanced biocompatibility, improved biointegration, and effective mitigation of both acute and chronic inflammation. Long-term electrophysiological recordings in freely moving mice revealed stable, high-fidelity neural signal acquisition for up to 8 months, maintaining a signal-to-noise ratio of approximately 20. This work establishes a durable and functionally stable neural interface, offering a promising platform for long-term neuroscience research and the development of next-generation BCIs.