That's very cool.
I have a few ePaper picture frames that don't use any power, and when you tap your phone to them it uses the power-over-NFC to boot itself and update the photo you send to it. It's such a cool idea and something I always felt like could be used more for displays that don't need to update very often.
This sounds really neat. Is it a commercial product or did you build them yourself?
This is so cool. Could you share more about where I could find them?