Novel Brain-Inspired Hierarchical Micro-Nanostructured Poly(3,4-ethylenedioxythiophene)/Polydopamine Neural Interface on Titanium Nitride Electrodes for Electrophysiological Signal Recording

The development of high-performance neural interfaces is critical for advancing brain-machine communication and treating neurological disorders. A major challenge in neural electrode design is achieving a seamless biological-electronic interface with optimized electrochemical properties, mechanical stability, and biocompatibility. In this study, we introduce a hierarchical micronanostructured poly(3,4-ethylenedioxythiophene)-polydopamine (PEDOT-PDA) coating on titanium nitride (TiN) microelectrodes engineered to enhance electrophysiological signal recording and neural integration. The PEDOT-PDA films were synthesized via potentiodynamic electropolymerization, achieving a 90% reduction in impedance (∼353 Ω at 1 kHz) compared to conventional gold (Au) electrodes (∼3795 Ω) and a 60% decrease relative to TiN substrates (∼890 Ω). The brain-inspired hierarchical micronanostructure mimics the extracellular matrix (ECM), improving cell adhesion and biointegration. Wettability analysis revealed a 63% enhancement in hydrophilicity, reducing the water contact angle from ∼70° for pure PEDOT to ∼25° for PEDOT-PDA. Biocompatibility assessments demonstrated excellent cell viability of ∼97% for PEDOT-PDA electrodes and superior cell attachment with extended filopodia formation, promoting long-term neural interface stability. The PEDOT-PDA interface outperforms conventional PEDOT and metal-based electrodes in electrochemical stability, biocompatibility, and signal recording efficiency, making it a promising candidate for next-generation brain-computer interfaces (BCIs).