Let Electric Ink Light Up Your Next Project

Pencil shavings make for cheap circuits

Conductive ink
Conductive ink
Conductive inkJeremy Cook

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.

Materials

  • Powdered graphite
  • White vinegar
  • Syringe
  • Elmer's clear glue

Stats

Time: 2 hours

Cost: $12

Difficulty: Easy

Instructions

  1. To make the ink, put powdered graphite in a cup, cover with vinegar, and stir. Let it sit for a few minutes.

  2. Once the graphite settles on the bottom of the cup, remove the clear liquid on top with a syringe.

  3. 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.

  4. 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.