The world’s strangest trampoline doesn’t bounce—it swings sideways and glides around corners. But no one can jump on it, because it’s smaller than the thickness of a human hair.

This miniature trampoline is just 0.2 millimeters wide and incredibly thin—only about 20 millionths of a millimeter thick. Its surface is patterned with regularly spaced, rounded triangular holes, giving it a distinctive perforated look. Despite its delicate appearance, it’s built for endurance. Once set in motion, it barely loses any momentum and can keep swinging for a very long time.

Unlike a traditional trampoline that bounces up and down, this one moves in multiple directions across its surface. At its center is an even smaller region—a “trampoline within the trampoline”—where motion follows a triangular path. This allows vibrations to flow precisely around sharp corners, a rare and valuable behavior in physics.

So why create a trampoline that no one can use? Developed by physicists from the University of Konstanz, the University of Copenhagen, and ETH Zurich, this device is designed to control the flow of phonons—quantized units of sound energy—in a solid. The trampoline is actually an ultra-thin waveguide made of silicon nitride, engineered to channel phonons using principles of topology, a branch of mathematics that explores spatial properties preserved under deformation.

The key innovation is the ability to guide phonons smoothly—even around tight 120-degree corners—with almost no loss of momentum. Fewer than one in ten thousand phonons reflect back instead of continuing along the path, a level of efficiency comparable to today’s best telecommunications technology.

Physicist Oded Zilberberg, from the University of Konstanz, led the design of this tiny trampoline. He studies topological effects in surface structures and how they can be applied to technologies like microchips, where directing signals precisely is critical. His collaborators in Copenhagen and Zurich brought the design to life, and their findings were recently published in Nature.

As for scaling up the trampoline to human size? Zilberberg has thought about it. He believes the concept could theoretically work at a larger scale—though anyone trying it should wear a helmet.

By Impact Lab