Published: July 20, 2021 By

Side-by-side images of a butterfly on clear plastic that is flat (left) and folded (right)

An Electriflow butterfly flaps its wings. (Credit: Purnendu)

Imagine opening up a book of nature photos only to see a kaleidoscope of graceful butterflies flutter out from the page.

Such fanciful storybooks might soon be possible thanks to the work of a team of designers and engineers at CU 麻豆影院鈥檚 ATLAS Institute. The group is drawing from new advancements in the field of soft robotics to develop shape-changing objects that are paper-thin, fast-moving and almost completely silent.听

The researchers鈥 early creations, which they鈥檝e dubbed 鈥淓lectriflow,鈥 include origami cranes that can bend their necks, flower petals that wiggle with the touch of a button and, yes, fluttering insects.

鈥淯sually, books about butterflies are static,鈥 said Purnendu, a graduate student at CU 麻豆影院 who is leading the project and who goes by a singular name. 鈥淏ut could you have a butterfly flap its wings within a book? We鈥檝e shown that it鈥檚 possible.鈥

He and his colleagues recently at the Association for Computing Machinery鈥檚 conference.

Artificial muscles

Purnendu explained that the team鈥檚 Electriflow designs don鈥檛 require motors or other traditional machine parts to come to life鈥攎aking them soft to the touch, just like real butterflies. They鈥檙e inspired by a class of 鈥渁rtificial muscles鈥 that were initially developed by researcher led by Christoph Keplinger at CU 麻豆影院 and are now available commercially through a company called Artimus Robotics.听

Artimus taps into a technology called hydraulically amplified self-healing electrostatic (HASEL) actuators. Unlike traditional robotic parts, which are often made of rigid metal, HASEL actuators get their power听from fluids.听The actuators rely on electrostatic forces to push oil around in sealed plastic pouches, said Eric Acome, a former CU 麻豆影院 graduate student who helped to pioneer the actuator technology. Picture how the shape of a ketchup packet will change when you squeeze one side.听

鈥淥ne of the main benefits of these actuators is that they鈥檙e versatile,鈥 said Acome, coauthor of the new study and the chief technology officer at . 鈥淭hey鈥檙e just pouches, but depending on the shape of that pouch, you can generate different kinds of movement.鈥

xSide by side images of a cartoon of Mickey Mouse's head with his ears wiggling

Top: An Electriflow butterfly and flower move inside the pages of a book; bottom: Electriflow can also create moving cartoons. (Credits: Purnendu)

They also emulate the natural world in which organisms of all kinds (think pufferfish or Venus fly traps) change their shapes to scare away predators and trap prey.听

鈥淪hape changing is a big part of communication and survival for certain animals,鈥 Purnendu said. 鈥淓ngineers have been on a quest to develop similar kinds of functions for computer interfaces.鈥

Wing flaps

Purnendu wondered if he could use the same concept as Artimus Robotics, or oils sloshing around inside pouches, not to just build new robots but to design soft, movable artwork. 听

Electriflow takes advantage of several different pouch shapes to create origami-like folds in flat plastic sheets. And it鈥檚 fast: Purnendu鈥檚 insects can beat their wings at a top speed of about 25 beats per second鈥攓uicker than most real butterflies and on par with some speedier moths.听

鈥淭his system is very close to what we see in nature,鈥 he said. 鈥淲e鈥檙e pushing the boundaries of how humans and machines can interact.鈥

The researcher said he hopes more artists and designers will use the tools he and his team developed to push those boundaries even farther. He imagines that one day, you might see origami animals that can fold themselves into various shapes from a flat sheet of plastic or cartoon characters that run and jump in the pages of books.听

鈥淭here are a lot of different geometries that we can play with,鈥 Purnendu said.

For now, he鈥檚 happy to watch his butterflies take flight.听

Christoph Keplinger, now at the 听Max Planck Institute for Intelligent Systems in Germany, was a coauthor of the new study.听Other coauthors at CU 麻豆影院 include Sasha Novack, graduate student in ATLAS; Mirela Alistar and Daniel Leithinger, assistant professors in ATLAS and the Department of Computer Science; Carson Bruns, assistant professor in ATLAS and mechanical engineering; and Mark Gross, director of ATLAS and professor of computer science.