G-putty is a polysilicone polymer infused with graphene. Polysilicone polymer is better known as Silly Putty®, a stretchy, moldable product sold in toy stores. Graphene is a highly-conductive carbon allotrope whose atoms are arranged in a mesh-like shape just one atom thick. The qualities of G-putty make it an ideal material for sensors. When a sensor is made of G-putty, it is sometimes referred to as a silly putty sensor. These sensors could be useful in several areas of industry including medicine and manufacturing.
The addition of graphene makes the substance conductive, as expected, but the researchers found that it also made it a high-performance material for sensing pressure, impact and deformation. Even a tiny strain or impact causes the electrical resistance of the substance to increase dramatically; over time, as it regains its original shape, the resistance tends to return to its original level. That happens because the mesh-like structure of the graphene allows it to form and break networks as the substance is deformed.
The researchers who discovered the special qualities of G-putty foresee its use in wearable medical and health-related sensors. A small silly putty sensor placed on a person’s chest, for example, could monitor the person's breathing, and would be helpful in managing conditions like sleep apnea. A sensor placed over the carotid artery could not only measure the person’s pulse rate but could also monitor their blood pressure continuously, which is a more difficult task. G-putty sensors could also be useful in other applications. For example, a G-putty pressure sensor could be used to monitor and collect data from industrial robots and autonomous driving systems.
G-putty was developed as a collaborative effort of Graphene Flagship at Trinity College Dublin and the National Graphene Institute (NGI) at The University of Manchester, led by Professors Johnathan Coleman and Robert Young, respectively. Although graphene had been added to polymers before, the capacities created by combining it with a stretchable and moldable substance surprised the researchers.