Through the skull, without surgery
The skull is not transparent. It scatters, absorbs and delays what passes through it, and it does so differently for every person. Anyone who wants to read the brain from outside meets this wall on the first day.
There are two ways to respond. One is to go through the bone with surgery. The other is to learn the bone. We take the second route: the device measures the skull it is sitting on and corrects for it, every time it is worn, without an external scan. Much of what makes this possible comes from fields that have nothing to do with the brain: seismology, radar, radio. The principles are shared even where the communities are not.
We do not believe the physics is solved. We believe it is solvable, and that the work of solving it is where the value of a non-invasive interface lies.