Scientists have discovered a way to fold origami — without physically touching it. By shining different colors of light on a sheet of Shrinky Dink plastic, researchers remotely bent it into various 3D shapes, according to a paper published Friday in the journal Science Advances.
The key discovery was figuring out how to fold the plastic in a specific order. “As anyone who has done origami — or folded their laundry — can tell you, the order in which you make the folds can be extremely important," Michael Dickey, a professor at North Carolina State University and an author of the study, said in a news release.
Here’s how Dickey and his colleagues got this to work: First, they used an inkjet printer to draw patterns of colors on the Shrinky Dink sheets where the engineers wanted the pages to bend. For anyone who hasn’t made Shrinky Dinks, they’re sheets of plastic that you can cut into shapes and draw on. When you stick them in the oven, the plastic melts and hardens.
The scientists here used light as a source of energy to heat up the plastic, instead of an oven. Because different pigments absorb different wavelengths of light, the lines printed onto the page heat up and bend only under specific lighting conditions. For example, blue ink absorbs red light, and yellow ink absorbs blue light.
By shining colored lights in a predetermined sequence on the sheet, the engineers were able heat up and bend the shapes in a specific order. When they shined a red light on the plastic, only the hinges colored in blue absorbed the light’s energy, heated up, and folded. And when the light switched to blue, only the yellow hinges bent. And so on.
Some patterns folded in a specific order even when only one color of light illuminated them. That’s because certain combinations of colors can absorb the same wavelength of light — it just takes some pigments longer to do so than others.
One sheet folded into what looked like a flower closing up at night. Another contorted into something that resembled a stack of badly folded clothes, and a third formed a coil.
The process is still in its preliminary stages. But as the method progresses, it could eventually make it a lot easier to assemble devices that need to stay sterile, like electronics or medical equipment, without ever touching them with dirty human or robotic hands.