Free-standing Nanofilm Electrode Arrays for Long-term Stable Neural Interfacings.

Flexible neural electrodes integrated on micrometer-thick polymer substrates offer important opportunities for improving the stability of neuronal activity recordings during cognitive processes. However, the bending stiffness of micrometer-thick polymer substrates is typically two orders of magnitude higher than that of nanofilm electrodes, making it a limiting factor in electrode-tissue interfacings. Here, we overcome this limitation by developing self-assembled nanofilm electrode arrays (NEAs) that consist of high-density, free-standing gold nanofilm electrodes. Chronically implanted NEAs can form intimate and innervated interfaces with neural tissue, enabling stable neuronal activity recordings across multiple brain regions over several months. As an application example, we track the activities of the same neuronal populations across odor discrimination reversal learning and illustrate how dorsal striatal neurons represent and update stimulus-outcome associations across multiple timescales. Our results underscore the potential of free-standing nanoscale materials for interfacing biological systems over long terms. This article is protected by copyright. All rights reserved.