Scientists at Georgia Tech have figured out how to create origami from light, no hands required. All the technique uses is a PowerPoint slide, a projector, and some resin. Georgia Tech mechanical engineer Jerry Qi and his colleagues exposed photo-absorbent resin to light patterns to get the material to bend into specific shapes, as they write in a paper in Science Advances.
The researchers put the designs they wanted to fold into a PowerPoint slide and projected that in grayscale onto resin in a Petri dish using a commercial projector, producing resin that folded itself into flowers, cranes, and a Miura fold.
The bending of the liquid resin is affected by both the time it’s exposed to light and the intensity of that light. Qi explains to ResearchGate that when the layer of liquid resin is exposed to the light, it shrinks the layers of resin at different rates. The layer hit directly by the light cures faster than the layers farther down. Because the different sides of the resin aren’t curing at the same rate, it creates what he calls “nonuniform shrinkage stress,” bending the resin along that path of light as it solidifies.
Since the layers of resin are so thin, it's very difficult to make larger objects using this technique. The resin origami figures they've made so far are smaller than the face of a quarter.
The Georgia Tech team suggests that this technique could be used to make soft origami machines, among other applications. They aren’t the only ones working on this technology, though. Recently, scientists at North Carolina State University created similar self-folding polymers that were controlled by different colored lights. Those researchers hoped to be able to remotely manipulate materials on satellites in space or for medical uses.