[TechniSol]

It might have been a capacitive layer inside the rear cover -perhaps etched or sprayed on with conductive paint as gross resolution would be more than adequate, or a resistive layer on the outside which would seem a bit less durable? Or perhaps the same guy who writes technical copy for Kobo also works for Ouija?

Honestly, it's an interesting idea and kind of cool, but I bet if they got to the testing phase they decided that accidental page turns were far too likely, or that the cost was simply prohibitive. Or maybe it just didn't work well or appeal to a focus group.

Hey, I had a crazy idea(yeah me, imagine that...), what if they made the back or sections of the back out of IR transmissive plastic? The groove down the middle would be ideal as an IR channel and allow for the image where they seem to show fingertip placement dead center of the back in the horizontal. Perhaps this idea accounted for the unusual design of the back? It would seem a lot more likely for a device designed to use IR rather than capacitance and might even be supported by the existing IR chip solution. A strip of sensors and LEDs on either side of the groove would do it.