Jiffy pop, an aluminum foil pan full of popcorn kernels and oil, is a staple of camping trips. Because of the way the pan is designed, when placed above an open campfire the kernels expand the aluminum top as they heat and pop, ultimately resulting in a bag of popcorn. The aluminum is lined with ridges, which unwind, allowing it to expand into a spherical shape.
Now, researchers at the University of Pennsylvania have used a similar concept to design two-dimensional sheets of a rubber-like material called liquid crystal elastomer capable of transforming into complex three-dimensional geometries, such as a human face, with heat. This has countless technological applications in areas such as flexible electronics, metamaterials, aerospace, medical devices, and drug delivery.
(Image credit: Felice Macera for artistic rendering).