➀ A subdermal optical device has been developed for precise brain monitoring and stimulation. It is ultrathin and based on CMOS technology, allowing for less-invasive studies of neural activity. ➁ The device, known as SCOPe, is flexible and lensless, with a total thickness of less than 200 µm. ➂ Initial tests have shown its potential in tracking brain activity and decoding motor behavior in non-human primates.