Researchers from Trinity College Dublin have combined nanomaterial graphene and the kid's toy Silly Putty, creating a sensor sensitive enough for a range of applications, including measuring spider footsteps.

In a study published in the journal Science, Jonathan Coleman and colleagues showed that not only does Silly Putty exhibit surprising properties by behaving like both a solid and liquid but that it is also capable of so much more when combined with graphene.

Mixing Graphene And Silly Putty

Coleman's team's general focus is on two-dimensional molecules such as graphene and finding applications for flat nanomaterials. The group also have a tradition of carrying out "kitchen physics," so they incorporate ordinary household items into their research to make it more accessible. It was because of this that Silly Putty became part of their work.

According to Coleman, Connor Boland, one of the study's authors, suggested that they use Silly Putty because not only is it an everyday object, but it is also a polymer, and graphene has been mixed in with polymers before.

Boland proceeded with making a graphene batch in water and adding Silly Putty. As the two materials were being mixed, graphene sheets stuck to the polymer, resulting in a black goo the research team fondly refers to as "G-putty."

Putting G-putty To The Test

When the researchers applied electrical current through the graphene-Silly Putty mix, they observed that the graphene-infused polymer was extraordinarily sensitive.

"If you touch it even with the slightest pressure or deformation, the electrical resistance will change significantly," said Coleman.

Specifically, just stretching or compressing the material by a percent of its normal size will change its electrical resistance by a factor of five. If other deformation-detecting materials were stretched or compressed with the same rate, they would only respond with a 1 percent change in electrical resistance. This makes G-putty 500 times more sensitive than them!

To further test G-putty's sensitivity, the researchers had a spider walk over the material and measured its footsteps. Given the graphene-infused polymer was able to detect the spider's tiny footfalls, it can also be used as an impact sensor.

G-putty Applications

The researchers envision G-putty being used as an electromechanical sensor to measure vibrations, particularly bodily motions. For instance, a squishy and unobtrusive sensor could be used in tracking breathing in babies, or it could be placed over a pulse point and used to gauge heart rate and blood pressure.

Coleman explained that continuously measuring blood pressure, for instance, is a great way to track the well-being of an individual. G-putty can do just that effectively and cheaply as well, so the researchers are already exploring commercialization opportunities for the material.

Photo: University of the Fraser Valley | Flickr