Engineers have long marveled at the precision and sophistication of mechanical functions in biological organisms. Emulating processes found in nature can result in a wealth of innovative design improvements—as a team of researchers found when they studied the wings of the earwig.
Using simulations and creating 4D replicas, researchers from ETH Zürich in Switzerland and Purdue University have been able study the structure and properties of the insect’s wings. Their findings could help create machines that are more adaptable, versatile and use less energy through the use of self-folding origami.
Like conventional origami, the earwig folds its wings along creases. However, the design of the insect’s wing is far more complex, incorporating stretching and tension that would cause paper origami to tear. That stretching and tension is essential to the wing’s ability to fold and lock itself into two different shapes: outstretched for when the earwig flies, and collapsed for when the insect needs to navigate its underground home.
The ability to hold two different stable shapes is known as bistability. The earwig’s wing springs from one shape to another without the need for an external actuator. Imagine paper origami that can fold itself into a swan and back out again without requiring any manipulation—and the stable shapes held in position without using extra energy.
Researchers believe bistability could be programmed into the design of a wide variety of devices, from robots to packaging to spacecraft to medical tools. “Bistable origami can be made out of any material, as long as you pre-stress it,” said Andres Arrieta, Purdue assistant professor of mechanical engineering, whose lab contributed to the study.
The possibilities of bistable devices include self-folding tents that don’t require assembly, collapsible solar sails for spacecraft, and shapeshifting robots that can reconfigure themselves to accomplish different tasks. Arrieta’s Programmable Structures Lab is currently researching stents that could stretch, bend and lock into the shapes of arteries more compatibly, which may allow them to work more efficiently and for a longer period of time.
Researchers like Arrieta and his team hope to harness bistability to create versatile and energy-efficient machines—another example of why engineers continue to look to the natural world for their inspiration.
Watch a Purdue YouTube video about how the earwig’s bistable wings could be used to develop adaptable multipurpose devices:
Read about origami-inspired robots at Meet the Swiss Army Knife of Search and Rescue Robots.