Thermally Drawn Multifunctional All-Hydrogel Fibers for Anti-Fibrotic and Multimodal Neural Interfaces.

Hydrogels have emerged as promising materials for anti-fibrotic neural interfaces due to their mechanical and chemical similarity to biological tissue. However, their use in multimodal platforms remains limited, owing to fabrication challenges in microstructuring multiple functional hydrogels into compact architectures. Here, a hydrogel thermal drawing process (HG-TDP) is presented that enables the co-fabrication of multiple thermoplastically deformable hydrogels into a single, compact, and multifunctional fiber. By optimizing key process parameters, all-hydrogel neural interfaces are developed that minimize gliosis through tissue-like mechanical compliance and enable post-implantation anti-inflammatory drug delivery via the hydrogel-based matrix. These fibers feature the compact integration of diverse hydrogel components, including a step-index optical waveguide, an electrically conductive hydrogel electrode, and a hydrogel-based microfluidic channel within a unified fiber structure. This integration enables multimodal neural interfacing, as demonstrated by high-quality neural signal recording, optogenetic stimulation, and localized chemical modulation of neural circuits. This work offers a scalable route toward compact, fully hydrogel-based neural interfaces that combine multimodal functionality with tissue-friendly, anti-fibrotic properties.