That’s a really interesting concept. A 3D keyboard where a single finger can activate three different keys could open up a lot of possibilities for compact input devices, VR/AR typing, or accessibility tools.
I do wonder how practical it is in real use — the learning curve, whether accidental inputs become a problem, and how fast someone could type once they get used to the depth-based key layout.
If you have the full paper or diagrams, it would be great to see how they solved the sensing and separation of the three input levels.