Researchers unveiled an implantable complementary metal–oxide–semiconductor (CMOS) fluorescence imager that achieves single‑neuron resolution deep within brain tissue. The device integrates miniaturized optics and on‑chip imaging to overcome scattering limits that have constrained optical access to deep structures. The team demonstrated neuronal‑scale fluorescence detection in vivo, showing potential for chronic neural monitoring, high‑resolution neuroscience studies and closed‑loop neuromodulation. The platform promises smaller, energy‑efficient implants that can map activity in regions previously inaccessible to optical imaging. Engineers and neuroscientists view the technology as a step toward implantable imaging tools that could accelerate basic research and, in time, translate into clinical neurotechnology applications.