Integrated Hydrogel Optical Fiber Electronics with Mechanically Robust Interfaces Enable Simultaneous Electrophysiological Recording and Optogenetic Modulation

Hydrogel-based electrodes and optical guides are promising tools for neural bioelectronics, offering tissue-like compliance, hydration capacity, and customizable functionalities. However, integrating multiple hydrogel modalities into a single device remains challenging due to material compatibility, cross-modal interference, and interfacial integration issues. In this work, an integrated hydrogel optical fiber electronics (iHOFE) platform is reported, including a step-index optical core, a conductive hydrogel layer, and a tissue-matched insulating sheath. By engineering the robust interface between each layer through chemical bonding and topological entanglement, a multilayer architecture capable of concurrent electrical and optical operation under dynamic mechanical deformation is created, thus high-fidelity electrophysiological recording and optogenetic modulation within the same region. The efficacy of the iHOFE is validated via two-month hippocampal implantation, demonstrating recording and manipulation of neural activity. This platform marks a significant advancement in developing multifunctional neural bioelectronics for interrogating and manipulating deep neural circuits compared to existing technologies.