Researchers at the University of Massachusetts Amherst have found a method of creating reversibly self-folding 3D structures.
An ultraviolet photolithographic patterning of photo-crosslinkable polymers was used to create reversibly self-folding origami structures on small length scales.
Polymer scientist Ryan Hayward said: "We have designed and implemented a simple approach that consists of sandwiching a thin layer of a temperature-responsive hydrogel with two patterned films of a rigid plastic."
"The presence of gaps in the plastic layers allows for folding by a controlled amount in a specified direction, enabling the formation of fairly complex origami structures."
The process makes use of a maskless lithographic techniqu,e based on a digital micromirror array device, to spatially pattern the cross-linking of the polymer films. These then melt away the uncross-linked areas with a solvent.
However, multiple layers of polymers can be patterned with broadly contrasting material properties by directly patterning the polymer films through the use of relatively few processing steps, Hayward adds.
Rather than using the step-by-step actuation of folds in a controlled sequence characteristic of conventional origami, the new process is based on ‘collapse’ designs, in which all folds are achieved more or less at the same time.
Hayward added: "Collapse-type origami designs have not been thoroughly explored in the past because of the difficulty of actuating tens or hundreds of folds with human hands; our technique removes this restriction and we expect that with the actuation scalability provided by our technique, vastly more complex collapsible structures may now be readily explored."
Photo:courtesy of UMass Amherst.