Usability wise, ePaper is an interesting technology. On one hand, it has amazing power consumption properties, using literally no power to display a static image. On the other hand, the refresh rate is way to slow for usable animation, and colors are generally limited to black and white, restricting where it can be implemented.
One idea, per Frank Buss’ write-up, is to use this technology along with an ESP32 module as a solar-powered, Wi-Fi-updateable display — a sort of electronic Post-it Note — that can stick to appliances and other metal objects via a magnet on its back. Additionally, the project includes three customizable buttons for user input as well as a cloud app to remotely change the message or picture being shown.
The ability to update it over the Internet opens up many novel applications. For example, install it on the fridge of your grandma, who might not be very proficient in using modern connected devices. Then you can send her birthday wishes, or remind her of schedules. And the buttons could be used as a feedback channel, like confirming a date. Or when installed at a public place, it can act as a bulletin board. Or it can be used for a modern form of internet connected graffiti or other art projects. The possibilities are infinite.
Though the prototype employed a fairly standard 2.7″ screen, Buss’ latest iteration features a 4.2” screen that can reveal images in black, white, and red, adding a whole new dimension to these displays. Instructions are to be upgraded to the new ePaper style at a future date.