Robust Neural Interfaces Enabled by Non-Deformable Adhesive Hydrogel Patch for Stable Chronic ECoG Recording

Micro-electrocorticography (micro-ECoG) with superior temporal and spatial resolution plays a critical role in precise brain mapping and decoding of brain activities. However, due to inevitable device-brain displacement in cerebrospinal fluid, the weak physical attachment of micro-ECoG devices on the cortical arachnoid tissue cannot ensure a stable neural interface to achieve durable and reliable ECoG recording over time. Herein, a robust neural interface is explored using a bio-adhesive hydrogel patch for stable chronic ECoG recording. To overcome the challenges in dimensional instability of hydrogels, such as swelling and shrinkage, which would impede the safe integration of micro-ECoG devices on fragile cortical surface, a non-deformable hydrogel patch is developed through rational design with balanced molecular chain topology to resist dimensional changes. The multifunctional non-deformable hydrogel demonstrates desired merits including rapid wet-tissue adhesion (within 30 s), anti-postoperative adhesion, excellent biocompatibility, ease of surgical handling, and scalability for large-scale production. Compared to conventional swelling or contractile hydrogels, the non-deformable hydrogel patch on a cortical surface can effectively inhibit fibrous capsule formation and glial cell recruitment. Furthermore, long-term recordings from micro-ECoG devices integrated with non-deformable hydrogel patches demonstrate excellent stability and high-fidelity electrophysiological signals, making it a promising advancement for chronic, durable, and reliable neural interface applications.