Graphene, which consists of carbon atoms linked together to form a one-atom-thick sheet, could certainly be described as a wonder material – among other things, it's highly electrically conductive, chemically stable, and is the world's strongest material. Silly Putty, on the other hand … well, it's an old-school kids' toy. Scientists recently combined the one with the other, however, to create sensors capable of unprecedented sensitivity.
Silly Putty is actually a type of polymer known as a cross-linked polysilicone. It has a gooey, viscous consistency when handled, yet also bounces like an elastic solid when thrown against hard surfaces.
In collaboration with Prof. Robert Young of the University of Manchester, an AMBER team led by Prof. Jonathan Coleman added a relatively small amount of graphene flakes to some of the putty (AMBER is an Irish materials research center, hosted by Trinity College Dublin). The resulting material, called G-putty, is electrically conductive.
What's particularly interesting about it, though, is the fact that its electrical resistance increases noticeably in response to even the tiniest deformation or impact. When Coleman and postdoctoral researcher Conor Boland (seen above) placed it against the chest or neck of test subjects, for instance, it was easily able to measure breathing, pulse and blood pressure. It could even detect the footsteps of small spiders walking across its surface.
According to the researchers, it is hundreds of times more sensitive than traditional sensors used in applications such as medical devices.
"The behaviour we found with G-putty has not been found in any other composite material," says Coleman. "This unique discovery will open up major possibilities in sensor manufacturing worldwide."
A paper on the research was recently published in the journal Science.