Building a keyboard isn’t a big project these days. Controller chips and boards are readily available, switches are easy to find, and a 3D printer can do a lot of what used to be the hard parts. But engineers at Purdue have printed a self-powered Bluetooth keyboard on an ordinary sheet of paper. You can see videos of the keyboards at work below.

The keyboards work by coating paper with a highly fluorinated coating that repels water, oil, and dust. Special inks print triboelectric circuits so that pressing your finger on a particular part of the paper generates electricity. We were skeptical that the Bluetooth part is self-powered, although maybe it is possible if you have some very low-power electronics or you manage the power generated very carefully.

Conductive nanoparticles are involved and — supposedly — they keyboards cost less than $0.25 to print. We presume that is after the fixed costs of setting everything up.

What would you use this for? It seems like paper isn’t going to be a good choice for long-term durable goods like laptops or cell phones. We can imagine a deli menu with buttons on it, perhaps, but it seems like it will be a while before that’s truly practical.

Still, if it is as robust as it looks, it should be interesting for something. We just aren’t sure what yet. Triboelectricity from key strikes probably isn’t going to run much electronics for very long, but it is fine for energizing some wires for a keypress. This isn’t the first paper generator we’ve seen, oddly enough.