Liberate your next electronics project from the constraint of wires and run current through a painted line of graphite instead. A DIY graphite paint won’t conduct electricity as well as a wire or an expensive commercial conductive ink. But it’s perfectly good for connecting LEDs to batteries in flexible circuits and making a sheet of paper touch-sensitive enough to play like a piano keyboard.
- Powdered graphite
- White vinegar
- Elmer’s clear glue
Time: 2 hours
To make the ink, put powdered graphite in a cup, cover with vinegar, and stir. Let it sit for a few minutes.
Once the graphite settles on the bottom of the cup, remove the clear liquid on top with a syringe.
Stir in about a teaspoon of glue to keep the graphite suspended. A thick line of paint has a resistance of a few kilohms per inch.
To test, use a small brush to draw lines connecting a 3-volt coin cell battery to an LED. Let the circuit dry and watch it light up!
This article was originally published in the January 2015 issue of Popular Science.