There are definitely external arrays that can work in locked in patients, but even when the stars align you'll usually be looking at something like 10-20 bits o

There are definitely external arrays that can work in locked in patients, but even when the stars align you'll usually be looking at something like 10-20 bits of data per minute. For most people it'll be much less than that, and for some it won't work at all. Generally speaking, these arrays are greatly outperformed by eye tracking, or even a nurse holding an A4 piece of paper and responding to blinks/grunts. This in and of itself wouldn't be a problem, as the tech is in its infancy, but the real issue comes is that researchers are focused on bullshitting the public and selling science fiction rather than improving the existing technology. Nobody understands how or why it works, and instead of learning about the brain we're just inventing new ML trickery.