Add graphene to get detectors that can measure breathing, blood pressure—and spider footsteps, reports Popular Science.

It’s easy to dismiss Silly Putty as a kid’s toy. But the stretchy material actually exhibits some surprising properties: It’s one of the softest plastics around, and it can behave like both a liquid and a solid, oozing when gently stretched but bouncing off surfaces like a rubber ball when hurled. And when you mix Silly Putty with graphene—strong, conductive carbon sheets with unusual physical properties—it becomes an incredibly sensitive strain detector that can track blood pressure, heart rate, and even a spider’s footsteps.