Inspired by the wings of earwigs, scientists have designed artificial wings that exhibit extraordinary folding abilities. Whereas traditional origami folding techniques are limited by rigidity and number of folding patterns, the technique developed by Jakob A. Faber and colleagues overcomes these challenges. Conventional origami techniques are used to fold 2-D structures into different shapes; while origami approaches have been recently improved by boosting the bending abilities of the creases, the design space for folding patterns remains unchanged. Earwigs' wings, however, exhibit a folding pattern that deviates from those seen in origami because of certain features that allow angular motions that fall under a "forbidden range," while maintaining stability. This capability relies on the presence of resilin, an elastic biopolymer that endows exceptional rotational or extensional spring based on its distribution throughout the wings. The resilin allows the wings to spring out from their folded position, without any mechanical energy input, before the wings "lock" into place. Here, the researchers first analyzed earwig wings and mimicked their design using mechanical springs, to understand the necessary rotations and folding. From these insights, they developed a preprogrammed folding design for 4-D printed "wings" that are initially closed before springing into an open position. Analysis reveals that the snap from a closed to open state occurs in 80 milliseconds, much faster than conventional diffusion-driven mechanisms and approximately the speed at which a Venus flytrap ensnares its prey.
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Journal
Science