Making Silly Putty Useful: Graphene and Polysilicone Make Extremely Sensitive Sensors

Researchers from Trinity College Dublin have discovered an unexpected material that could conduct electricity more effectively: Silly Putty® or polysilicone. By collaborating with the National Graphene Institute (NGI) at The University of Manchester, the research team was able to produce extremely sensitive sensors with this conductive polymer.

Professor Jonathan Coleman, a faculty member of Trinity College Dublin and the lead researcher of the study published in the prominent journal Science, worked in collaboration with Polymer Science and Technology Professor Robert Young of The University of Manchester to explore the potential of their graphene research to create devices and diagnostics in healthcare and other sectors that would cost less than other devices in the market.

After discovering that the electrical resistance of putty infused with graphene or "G-putty" was extremely sensitive to the slightest deformation or impact, Professor Coleman mounted the G-putty onto the chest and neck of human subjects and used it to measure breathing, pulse, and blood pressure. Proving to be several hundred times more sensitive than current sensors, the G-putty was also able to detect the footsteps of small spiders.

"What we are excited about is the unexpected behavior we found when we added graphene to the polymer, a cross-linked polysilicon. This material is well known as the children's toy Silly Putty. It is different from familiar materials in that it flows like a viscous liquid when deformed slowly but bounces like an elastic solid when thrown against a surface," said Professor Coleman. "When we added the graphene to the silly putty, it caused it to conduct electricity, but in a very unusual way. The electrical resistance of the G-putty was very sensitive to deformation with the resistance increasing sharply on even the slightest strain or impact. Unusually, the resistance slowly returned close to its original value as the putty self-healed over time."

Scientists at the NGI at The University of Manchester then studied the structure of the material and produced a mathematical model of the deformation of the material that explained the effect of its structure upon its mechanical and electrical properties.

"The endless list of potential applications of graphene never ceases to amaze me. We have now developed a new high-performance sensing material, 'G-putty', that can monitor deformation, pressure, and impact at a level of sensitivity that is so precise that it allows even the footsteps of small spiders to be monitored," said Professor Young. "It will have many future applications in sensors, particularly in the field of healthcare. The collaboration has been undertaken under the umbrella of the European Graphene Flagship, in which Trinity College Dublin and The University of Manchester both play a prominent role. It is an excellent example of what is being achieved in the flagship program."