Inspired by origami, the ancient Japanese art of paper folding, a team of Johns Hopkins engineers has developed a technique that harnesses the power of ultraviolet light to prompt a new hybrid atomistic-polymer nanomaterial to fold into intricate shapes—including origami’s iconic bird.
The method, described in a recent cover story in Advanced Intelligent Systems, could enable the fabrication of novel devices for use in flexible electronics, photonics, and biosensors, according to David Gracias, professor in the Department of Chemical and Biomolecular Engineering at Johns Hopkins Whiting School of Engineering. The research is another step in the evolution of synthetic materials.
“The key innovation is that this is a kind of light detector ‘skin’ and we have shown that we can fold it into 3D shapes,” said Gracias about the project.
According to Gracias, graphene, only recently discovered and still being perfected, is “one of the great inventions of the last 20 years. It’s one atom thick—these are the thinnest materials ever.” Thin but inherently two-dimensional, much like a sheet of paper, monolayer graphene covers a lot of area, he said.
“If you build a device using a two-dimensional film, it takes up a lot of real estate,” said Gracias. “So in applications like wearables, you may want to take the 2D device and make it more three-dimensional.” Particularly important for use in wearables and other applications, he said, is the ability to create three-dimensional, flexible shapes that curve and fold in opposite directions the way origami birds do.
David Gracias
The team discovered the first evidence that a two-dimensional graphene pattern can fold itself into a three-dimensional pattern when driven by different chemical affinity between solvents—like a blueprint of a building assembling itself into a 3D model. Gracias said the resulting 3D object could function as a photodetector—a device that converts light into an electrical signal, like a camera. The photodetector can also show the angle at which light is directed.
The origami bird is just proof of concept: the team anticipates that this approach could be used in 3D integrated designs for wearables, autonomous actuators, flying or swimming robots, energy harvesting devices, and biosensors. Complex shapes could be important for soft robotics, and a light source akin to solar can provide renewable and remote pathways to fuel the process, Gracias said.
“If you can get light and convert it to voltage you can create an optical sensor, energy harvesting device, or biosensor,” said Gracias.
Contributors to the research from Johns Hopkins include Tao Deng, Qi Huang, Michael Shen, Weinan Xu, and Yuqian Yang from the Department of Chemical and Biomolecular Engineering; Jacob Khurgin, Yida Lin, Tengfei Lu, and Susanna Thon from the Department of Electrical and Computer Engineering; and ChangKyu Yoon from the Department of Materials Science and Engineering.