Adding graphene to the children's toy Silly Putty (polysilicone) yields a compound, dubbed G-putty, that conducts electricity and that is sensitive to deformation or impact. The material could be used in medical sensors.
Researchers combined small sheets of graphene that were one nanometer thick with the silicone polymer, creating a microscopic electrical network. Prof. Jonathan Coleman from Trinity College Dublin and Prof. Robert Young of the University of Manchester announced their search results in Science. Their research is sponsored by AMBER (Advanced Materials and BioEngineering Research) in Ireland.
According to Coleman, combining graphene and plastics to improve electrical, mechanical, thermal, or barrier properties is a common practice. The resulting compounds perform as expected. However, “the behavior we found with G-putty has not been found in any other composite material.”
Silly Putty flows like a viscous liquid under slow deformation, but it also can bounce if thrown at a surface. When the researchers added graphene, electrical resistance was sensitive to deformation; the sensitivity increased sharply with even slight strains or impacts. It detected deformations made by a spider stepping on it. Resistance returned to near-normal as the putty healed itself.
Coleman and Young envisage using the new material in medical sensors. In one test, they mounted G-putty connected to electrodes connected to a computer on the chest and neck of human subjects. The putty placed near the carotid artery was able to detect a pulse; the slight deformation caused by the pulse interrupted electrical current flowing through the putty. The extreme sensitivity – estimated to be 250 times that of the cheapest metal-based sensors – can monitor vital signs accurately and less invasively than traditional tools, like a blood pressure cuff.
The team is actively pursuing commercialization for G-putty.