Cost‐Effective Ti/Al/Ni Multilayer Neural Probes With In Vivo Recording Performance Comparable to Ti/Au Neural Probes

ABSTRACT Neural probes are essential electrophysiological tools for investigating brain function. Gold (Au) has traditionally been used as the standard signal‐line material due to its high electrical conductivity and excellent biocompatibility. However, global factors, including the COVID‐19 pandemic and associated supply‐chain instabilities, have driven a sharp rise in Au prices over the past decade, substantially increasing the cost of neural probe fabrication. Here, we introduce a neural probe that replaces Au with aluminum (Al), a widely available, low‐cost metal with high electrical conductivity and extensive use in semiconductor manufacturing. To ensure stable electrical performance despite Al's intrinsic susceptibility to oxidation, we developed a Ti/Al/Ni multilayer metal stack engineered to enhance interfacial adhesion, suppress spontaneous oxide formation, and mitigate electrochemical reactivity in electrolyte environments. Using this optimized architecture, the total fabrication cost of a Ti/Al/Ni multilayer neural probe was approximately USD 217—roughly one‐quarter the cost of a probe fabricated with Au under identical process conditions. The resulting probes exhibited robust electrical and chemical stability across multiple evaluations, and in vivo recordings demonstrated neural signal quality comparable to that of conventional Ti/Au neural probes. This approach can expand accessibility to high‐quality neural recording technologies, particularly in resource‐limited research settings.