Mechanically Tissue‐Like and Highly Conductive Au Nanoparticles Embedded Elastomeric Fiber Electrodes of Brain–Machine Interfaces for Chronic In Vivo Brain Neural Recording

Abstract Implantable neural probes are a crucial part of brain–machine interfaces that serve as direct interacting routes between neural tissues and machines. The neural probes require both mechanical and electrical properties to acquire high‐quality signals from individual neurons with minimal tissue damage. However, overcoming the trade‐off between flexibility and electrical property is still challenging. Herein, a fiber neural probe, composed of core polymer and Au nanoparticles (AuNPs) on the outer shell, is fabricated by absorbing Au precursor following in situ chemical reduction with a variation of percolating and leaching time. The proposed fiber exhibits excellent electrical properties, with an electrical conductivity of 7.68 × 10⁴ S m⁻¹ and an impedance of 2.88 × 10³ Ω at 1 kHz, as well as a Young's modulus of 170 kPa, which is comparable to that of brain tissue (≈100 kPa). Additionally, the AuNPs fiber neural probe demonstrates extremely stable in vivo electrophysiological signal recordings for four months with reduced foreign body responses at the tissue–probe interface. Furthermore, this innovative approach encourages a new paradigm of long‐term recording in the fields of neuroscience and engineering to better understand brain circuits, develop bioelectronic devices, and treat chronic disorders.