CROSSBRAIN addresses the pressing need for minimally invasive, adaptive brain stimulation tools capable of tackling neurological disorders such as epilepsy. In an era marked by rising neurological disease burden and limited treatment options, CROSSBRAIN proposes a transformative approach by merging neuromorphic computing, advanced nanomaterials, and wireless microdevices. The project aims to develop µBots—tiny, implantable devices capable of sensing and modulating brain activity through multiple physical modalities (electrical, mechanical, optical, thermal) with unprecedented spatial and temporal precision. These µBots function autonomously in a federated network, enabling closed-loop, patient-specific neuromodulation. The integration of AI-based neuromorphic control and biocompatible nanomaterials supports long-term implantation with minimal immune response. CROSSBRAIN's technological innovations are expected to advance fundamental neuroscience, support new therapeutic strategies, and contribute to EU leadership in brain-computer interfaces and neurotechnology regulation. Social sciences and ethics are embedded to assess human relevance, regulatory acceptability, and societal impact. The project aligns with the EU’s strategic goals in health innovation, neurotechnology, and responsible AI.