Researchers at MIT published Nature Biotechnology results demonstrating micrometer‑scale, light‑powered electronic devices chemically attached to circulating monocytes that home to inflamed brain tissue and stimulate neurons—an approach the team calls 'circulatronics.' The hybrids aim to deliver minimally invasive brain stimulation to deep regions inaccessible to traditional implants. The devices are subcellular in size (~10 μm), integrate semiconducting polymers and electrodes, and exploit immune cell trafficking to cross the blood‑brain interface. In mice, hybrids localized to brain inflammation and achieved micrometer‑level stimulation with limited tissue disruption. Authors pitched the technology as a potential route to avoid neurosurgery for implant placement, but noted translational hurdles remain, including long‑term safety, immune responses, and light delivery in humans.