Just before they showed the woman, they showed that they were using a 100-sensor array in a mouse, and it sounded like they used the same on her. A 100 pin connector is no small thing.
They also explained that mounting the sensors inside the brian gave a much better signal that using external eeg pickups.
I wonder if it would be worthwhile to create a combination of internal and external sensors. The internal would provide the fine sensing and the external would augment and/or facilitate the sensing. One might be able to implant permanent sensors under the skin but outside the skull. As the technology and experience advances, the external sensors’ performance could be considerable.
And the part with the robo-monkey was pretty cool too.