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Shapeshifting Materials Could Transform Our World Inside Out

From medicine to space travel, Chuck Hoberman's shape-shifting is expanding scientific research.

By Stephen Ornes
Nov 15, 2020 12:00 AM
A sneak peek at Hoberman’s latest prototype: a sphere that transforms shape, size and color by turning itself inside out. (Credit: Yana Paskova)


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This story originally appeared in the December issue of Discover magazine as "Scientist in Toyland." Support our science journalism by becoming a subscriber.

It’s easy to pin labels on Chuck Hoberman, but hard to stick with just one. He’s an inventor, an artist, a tinkerer. He’s a designer, an engineer, a transformer. He’s a toymaker — the brains behind the colorful, expanding Hoberman sphere, which you and your kids have been playing with since the early 1990s (and which earned a place in the Museum of Modern Art’s permanent collection). Thematically, Hoberman’s work lands him at the intersection of art, architecture, design and playthings. Physically, he works sometimes from an airy room on the second floor of a house-turned-office-suite near Harvard Square in Cambridge, Massachusetts.

The Cambridge office is tidy, with white walls and plenty of light. The surfaces are usually cleared, but today they’re cluttered with the material expressions of his geometric dreams: Models made of two-dimensional pieces, hinged together to form 3D structures that deform, bend or otherwise fold in prescribed ways. They are made out of whatever material Hoberman had at hand when inspiration struck — paper, precisely cut in regular polyhedra with tape linkages; folded cardboard; laser-cut plywood; hard plastic sheeting. Larger models, wrapped in paper and foam sheets, sit in big boxes on the floor. Some look like reconstructions of impossible objects from M.C. Escher-like visions.

At Stony Brook University, his dynamic windows project (right) is both artistic and functional as a piece of shading. (Credit: Courtest Hoberman Associates, Hoberman.com)

He picks up a structure that looks like bulldozer treads but is black on the outside and orange in the interior. It has triangular sides, now it has octahedral sides, and now it’s collapsed, flat. “There are underlying geometric principles that let them move the way they do,” he says, turning the structure inside out, “and that’s my usual starting point. I work from a kind of geometric lexicon.” He always seems to be fidgeting, as though the only way to talk about shapeshifters is to stay in motion.

Hoberman is dressed in black — jacket, shirts, pants, glasses — with white hair combed straight back. His long face is both skeptical and serious. He lays a ruler on one of the tables. The models on the right side, he says, represent the past: Decades of evolved geometric ideas. These designs don’t look like toys, per se, but rather like the Platonic forms of playthings, toys reduced to their purest elements of movement, form and mathematics.

Transformation is their common denominator, and he returns to that idea because it’s so readily obvious in the world. “Basically, wherever you look, at the clouds or whatever, everything is transforming constantly and doing it in a fluid, smooth and continuous way,” he says.

He’s been obsessed with physical change since he began experimenting with pulleys and levers during his art school days in the 1970s. “I’m maniacal in being focused on this concept,” he says. His work is driven by big, roomy questions: How does one shape turn into another? The engineers who enlist his help ask that question differently: How can a device — at any scale, from origami organs up to a building — be designed so that it smoothly deforms from one thing into another? Hoberman’s expertise makes him particularly appealing to researchers interested in machine intelligence of a sort — not the kind that requires writing better algorithms, necessarily, but the kind built into the physical structure itself, an intentional motion.

(Courtest Hoberman Associates, hoberman.com)

Which brings us back to that ruler and the objects to the left. They’re the future: An entirely new taxa of inflatable, origami-based structures that he’s asked me not to describe in detail, partly because they’re not published or patented yet, and partly because they’re not his alone. They’re the kernels of wild design projects with engineers, roboticists, computer scientists, an origami expert, mathematicians and even biologists. They run the gamut from soft robotics (how can we fold up bots that can help people in disaster areas anywhere?) to collapsible habitats (how can I pack an origami house into my backpack, and take it to the moon as a place to live?) to printable, inflatable, replaceable organs (how can I pack the most blood vessels into the least surface area?).

His partners say Hoberman brings the vision to design shapeshifters for which change is not only intentional, but also necessary, inevitable and critical to some function or device. Though it’s largely up to them to find that function; they explore the ways to put his elemental shapes to work. That includes mapping out geometric and mechanical properties, but also employing them for things like pop-up emergency medical centers during disease outbreaks, for example, or using them in a wall to make a room soundproof.

“Chuck spans all the disciplines: art, science and toys,” says MIT computer scientist and renowned origami expert Erik Demaine. He first met Hoberman when both of them contributed pieces to a 2008 show at the Museum of Modern Art, in New York. In 2013, together with MIT engineer and soft robot pioneer Daniela Rus, they co-taught a class at MIT on invention and design. “He’s definitely the expert in transformable structure design,” says Demaine. “He founded it.”

Hoberman created art installation “Ten Degrees” in Cambridge, Mass., which allows visitors to move sculptures weighing several hundred pounds as easily as they might manipulate his famous toy.

Plays Well With Others

Most of Hoberman’s early achievements — the toy-building, a stage set for U2, and a host of other projects — were largely solo gigs. Not so anymore: He has become a go-to expert for researchers in search of smart, built-in design. In 2018, he worked with a student and marine biologists to develop a netlike contraption that unfolds itself in the deep ocean and traps fragile sea creatures without harming them. In 2019, engineers at Columbia University adapted the Hoberman Flight Ring, another toy, as the basis for “particle robots,” a swarm of devices that remain useless and stationary on their own but can move and complete tasks when they work together. A 2019 exhibit at the Cooper Hewitt, Smithsonian Design Museum in New York featured an “origami membrane” for a 3D-printed, engineered organ, designed by Hoberman and colleagues at Harvard’s Wyss Institute for Biologically Inspired Engineering.

In 2017, Hoberman was part of an interdisciplinary project group, including Johannes Overvelde (now at AMOLF, a government lab in the Netherlands) and Harvard engineer Katia Bertoldi, that introduced a family of reconfigurable structures based on repeating mathematical patterns called tessellations. In an editorial in Nature, a roboticist called the paper “an algorithm for architectural origami,” noting that such an approach could lead to reconfigurable devices that transform to fit their environments. Nerds around the world might celebrate them as “origami robots.”

“It wouldn’t have happened without Chuck,” says Bertoldi, a frequent collaborator. “We wouldn’t have explored these territories without being influenced by his spirit, and style, and creativity.”

About once a month, Hoberman packs up some models from the future side of the ruler and walks a few blocks north to visit Bertoldi in her office across the street from Harvard’s Museum of Natural History. A tall bookcase displays shelf upon shelf of geometric designs and structures. They look like cousins of Hoberman’s designs — they’re similarly built to change — but instead of being made from cardboard, most are either 3D printed, laser cut, or cast out of plastic or more flexible polymers.

I visited Bertoldi at her office in fall 2019, on a day she usually meets with Hoberman and often Demaine to exchange ideas, to give updates on projects and to fidget together. To my dismay, Hoberman had cancelled on account of me.

Like Hoberman, Bertoldi fidgets, all the time, with her mind as well as her hands. She takes down a plastic, 3D printed, gridlike matrix that, with a quick movement of her wrist, collapses to two dimensions, then pops back into three. She’s an engineer, not an inventor, and her research focuses on structures that get their properties from the way they’re put together. She calls them “architected materials,” but that’s her engineer side talking; others refer to them as “metamaterials.”

She tells me the story of how she and Hoberman met. “It’s funny in all directions,” she begins. It starts with the Twist-O, a fantastic plastic contraption made of a bunch of colorful Xs fastened to each other by small gears at the tips of their arms.

It’s a compact sphere, but when you twist the Xs, the thing expands in your hands, mechanically tripling its volume to become a much bigger sphere, now with the Xs serving as a skeletal scaffolding. To the U.S. Patent Office, the toy is a “reversibly expandable doublycurved truss structure,” but try selling that to a kid. “Twist-O” was easier to market.

In 2011, a friend of Bertoldi’s went to New York City for a weekend with his girlfriend, and the pair returned with a gift: A cheap knockoff of a Twist-O. She’d never heard of Hoberman. (“I knew the toys, but I didn’t know him,” Bertoldi says.) But the timing was serendipitous because she had been thinking about how to print three-dimensional structures that can collapse in predefined ways, and then un-collapse. That idea could be useful, for example, if you wanted to build a joint for a robot made out of only one piece, or you wanted to construct a building with collapsible walls.

The Twist-O does exactly that, in a way. Its expansions and contractions feel almost involuntary because that’s how Hoberman built it. Anyone from ages 2 to 102 can make it happen, and the secret to its ability for delight is built into its structure. However, Bertoldi observed that it was discrete, which means it was made of many parts. She instead wanted a continuous version of the same idea, one made of one piece of material. So, that’s what she created.

Chuck Hoberman (Credit: Yana Paskova)

Where a Twist-O has 26 Xs and 48 hinges, Bertoldi’s creation was an inflatable plastic sphere with 24 dimples and a small nozzle, like the hole used to insert an air pump needle into a basketball. When she used a syringe to remove the air from her creation, it crumpled in a specific way to form a shape known as a rhombicuboctahedron — a solid that has 24 vertices where three squares and a triangle come together. Because it buckled, and because the shape reminded Bertoldi of a buckyball, she christened it “buckliball.”

Don Ingber, a pioneer in the field of biologically inspired design and the founding director of Harvard’s Wyss Institute, saw Bertoldi’s work and insisted that she meet Hoberman, who had just begun teaching at Harvard’s Graduate School of Design. So the two talked, and fidgeted and played with toys, and brought in Overvelde or Demaine for brainstorming sessions.

Bertoldi says all of their designs begin with intuition, which to her engineering sensibility “is kind of scary.” To come up with new mechanisms, she says, they first need a geometric concept, a kind of mechanical hypothesis, which is abstract. Those concepts often begin with folding paper, or laser-cutting plastic, or making hinges. From there, they try to figure out how to encode some mechanism — buckling, folding, growing, changing dimension, inflating — into the structure of the material itself.

Their contraptions don’t always pan out. “There’s a lot of trial and error,” says Bertoldi. But at the same time, they’re never at a loss for ideas. “We get inspired by the structure that you see out in the world, in nature,” she says. “We always have to keep our eyes wide open.”

The Only Constant

Mercedes-Benz Stadium, home to the Atlanta Falcons and the Atlanta United FC soccer team opened — literally — in 2017 with a twisting, retractable roof that Hoberman helped design. (Credit: Courtest Hoberman Associates, hoberman.com)

It’s tempting to trace Hoberman’s evolution as an inventor through his works. As a student at Cooper Union, an art school on the edge of Manhattan’s East Village, he built terrifically complicated kinematic sculptures — big installations with moving parts that, if the studio were dark enough, would look like looming torture devices. He shows me videos of an experimental people-tilter. One person turns a crank, which pulls a rope, which threads a system of pulleys, which pivots two wooden platforms, each supporting an art student, between standing and prone configurations.

“I didn’t yet have this concept of transformation,” he says. “I was thinking, OK, art is supposed to change your viewpoints. Let’s literally change your viewpoint.”

Fast forward a few years, and Hoberman found himself designing a home for outer space. After art school — and graduate school at Columbia, in mechanical engineering — he joined Honeybee Robotics, a small industrial robot outfit then working out of SoHo. At the time, Honeybee focused on mechanisms for quick-connect hardware systems for automated robots; Hoberman’s inventive spirit fit with the company’s focus on pushing design forward. “I’d found something where I can cut up paper and tape it and make money and discover new things,” he says.

With a grant from NASA, Hoberman worked with Honeybee to design a collapsible habitat that could be deployed to space and possibly attach to the International Space Station (which hadn’t launched at that point but was nearly complete). NASA never planned to build the module, but the agency wanted a proof-of-concept project that hinted at the possibilities for space architecture. “They had this giant space frame and were trying to figure out how to build huge structures in space,” he says. Honeybee has gone on to design some of the robotic arms and tools used to collect and analyze soil from the surface of Mars, among other robots. And last year, Hoberman was part of a team who received another NASA grant to develop space habitats. Design by design, Hoberman continued to advance his ideas about how structure and design can be used to infuse an intentional motion into a material.

He didn’t always need pulleys, ropes and platforms; he realized that he could achieve transformation in design through the careful planning of linkages. The right mechanism — the right hinge, or connection, or pivot — could elegantly obviate the need for more cumbersome, clunkier, moving parts.

Then, 1990 brought the Hoberman Sphere, which puts that idea into practice: The plastic ribs of the sphere join together at precisely calculated junctures so that, as they expand, they form straight lines radiating outward from the center.

Fast forward again, this time into the early 21st century. For the 2002 Winter Olympics in Salt Lake City, Hoberman designed a giant aluminum arch that opened and shut like an iris over the medal stage. It had a diameter of 72 feet and more than 15,000 pounds of moving parts. In 2008, he was approached by the band U2 to design the giant assemblage of transformable video screens that would be part of the “claw” stage, the centerpiece of their 360° World Tour. The claw was a monster that stood more than 150 feet high.

“It was just one of those things where it felt like you were sort of picked out of your normal life and then, all of a sudden, you’re working for Bono,” Hoberman says. “It was an absolute feat of extreme engineering, and i was my baby.”

When the Mercedes-Benz Stadium — home to the Atlanta Falcons and the Atlanta United FC soccer team —opened in 2017, it wore as its crown a giant, retractable roof that Hoberman helped design. The action of twisting, and opening, and changing, is unmistakably Hoberman.

A Flash Between Two Long Nights

Back in Hoberman’s office, he points out design prototypes that are incomplete and says that many, if not most, of his geometric thought experiments don’t work in the real world.

(Credit: Courtest Hoberman Associates, hoberman.com)

I look closer at the ones on hand: Structures made of squares, rectangles, triangles and other polygons, meticulously numbered and taped. I pick one up and flip it between states and ask him where the ideas come from.

“Thought is only a flash between two long nights,” Hoberman says, quoting Henri Poincaré from his 1905 book, The Value of Science, “but this flash is everything.” He picks up one of his models that looks like a tic-tac-toe board extended into three dimensions. If you nudge it slightly on one side it falls flat, but it’s easy to refigure into its three-dimensional form. This was one of his first experiments. It began with a dream hypothesis — not a hypothesis in the usual sense of “educated guess,” but a vague notion, materialized visually but not in words or formulas, about how a certain design would move in space.

“I woke up in the morning and thought, ‘I have an idea,’ and I cut up a box and made this thing,” he says, flipping it between states.

I realize — for the first time during our conversations — that as the toymaker began to collaborate with others, he also began designing forms that can combine with others. Hoberman calls them “prismatic structures,” and they’re like macroscopic facsimiles of the regular, repeating geometries found, for example, in the molecular structure of crystals. And it’s in these repeating configurations, these geometric collaborations, that the structure gets its ability to deform, change and perform its inevitable function. Intentional motion, or that unusual stripe of machine intelligence, can arise from collaboration.

I look again at the future side of the ruler. Unlike the prismatic structures, these inflatables have nozzles, and are sealed, and change from one thing into another if you blow into them. Hoberman picks one up to demonstrate, and as he blows, a three-dimensional, right-angled structure unfolds itself from a flat plastic sheet. It’s as though he and his co-conspirators have reinvented the bellows — for decidedly 21st century uses — like space houses, or robots that can explore disaster areas, or organs.

It’s impossible to predict the future, but it is tempting to poke these hard, balloonlike structures and imagine a time when things like inflatable organs and collapsible, foldable buildings aren’t only possible but surprisingly, astonishingly simple and even humdrum. As in, why didn’t we think of those sooner?

Stephen Ornes lives in Nashville, Tennessee, and is the author of Math Art: Truth, Beauty, and Equations.

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