Rubber bands aren’t typically used for anything much more elaborate than securing a sheet of paper into a tube. But the addition of substance du jour graphene gives them a new, scientific function. “Graphene is a very thin piece of graphite, close to one atom thick,” says Jonathan Coleman, professor of chemical physics at Trinity College Dublin. “They’re two-dimensional sheets of carbon — and they conduct electricity.” He has used these conductive rubber bands to measure heart rates, breathing and muscle movement. Here’s how to add some graphene power.
Gather your ingredients
You’ll need lots of pencil lead, which can be found in standard or graphite-only pencils; a cheese grater; washing-up liquid; water; a blender; a big rubber band; a battery; some toluene. “Toluene is a chemical that you find in a lab,” says Coleman, suggesting turpentine as a substitute. “It will still work and it’s easy to source.”
Make the graphene
First, submerge the rubber band in either toluene or turpentine for a couple of hours, and it will swell up. “When you put it in the turps you get little holes,” says Coleman. Now grate plenty of graphite into a kitchen blender. Add half a litre of water and a few droplets of washing-up liquid and blitz it up. The black, watery result looks nasty, but it contains your graphene.
Infuse the rubber band
Put the rubber band into the graphene. The graphene sheets are about a thousandth of a millimetre thick, so they fit in the holes. After four hours the rubber band will be electrically conducting. “It’s like putting wires into Swiss cheese. It’s not that the cheese is conductive, it just appears that way.”
Enjoy the results
Warm the band in an oven until it is dry, then hook it up it to a battery. “If you connected that to an athlete’s leg, then you could monitor what they’re doing by measuring the electrical resistance,” says Coleman. “If you had a little chip to measure the current and a Bluetooth transceiver, you could monitor it through your iPhone. That’s the future.”
