I'm really excited to see electric field sensing mature like this, but I sense a potential problem with RF emissions down the road. Can this stuff get FCC class-B certification?
What worries me about this approach is the need for calibration. I don't see anywhere that indicates they've tested to see the effects of the wearing down of the topcoat and conductive spray layer upon the accuracy. It would be cool to be able to simplify a light switch installation to slap(electrodes)-spray-spray-calibrate, it would suck if I had to re-calibrate once every few years.
Now if we can figure out how to beam low-voltage, low-amperage power over building distances and through insulation, then we could remove a lot of copper runs. Beam just enough low power to drive and sense these kinds of control surfaces, and control relays sitting in front of the actual devices' electrical connections.
[1] https://transition.fcc.gov/oet/spectrum/table/fcctable.pdf
Once on a capacitive screen controller design I had to stick in some pseudo-randomization on the electrode PWM to avoid this coupling. It was a pain in the ass.
See for example: https://www.enocean.com/en/enocean_modules_902mhz/