Demonstration of dynamic driving on a rotating platform. 2026 fleXLab EPFL CC BY SA
A team including EPFL engineers has designed a rotating platform whose controlled spin can make flexible beams snap between two stable states. The simple, fast method can encode binary information directly into materials without electronics.
There is something universally appealing about the slap bracelet, and the way a simple tap causes it to switch between a straight shape and a curled one. What you probably didn't know is that a slap bracelet's satisfying snap is the same principle behind bistable structures. These can toggle between two stable positions (one representing 0 and the other 1) to store data directly within their physical forms as mechanical bits (m-bits).
Because of their exciting potential for efficient control of robotic and other mechanical systems, researchers have been engineering special materials with programmable structures (programmable metamaterials) for years. But until now, actual programming of such systems has been a major challenge: mechanical bits must typically be controlled individually, which is extremely cumbersome and time-consuming.
Now, researchers in the Flexible Structures Laboratory (fleXLab) in EPFL's School of Engineering, the Dutch research institute AMOLF, and Leiden University have found a way to program metamaterials globally with a surprisingly simple solution: rotation. By tuning a spinning platform's speed, direction, and acceleration, the researchers can harness forces arising in a rotating system - such as centrifugal and Euler forces - to make elastic beams snap back and forth, creating a simple new way to 'write' multiple mechanical bits at once. The breakthrough has been published in Science Advances.
Memory storage is a critical component of mechanical computing and soft robotics applications, which could be used to develop future systems that embed elements of physical intelligence directly into the very materials used to build them.
"The beauty of our approach, which we call 'dynamic driving', is that it allows us to globally set the memory of a mechanical metamaterial system using rotation," explains fleXLab head Pedro Reis. "Memory storage is a critical component of mechanical computing and soft robotics applications, which could be used to develop future systems that embed elements of physical intelligence directly into the very materials used to build them."
Spelling with a single spin
To demonstrate dynamic driving, the researchers 'wrote' all 26 uppercase letters of the alphabet using five finger-sized silicone beams mounted on their rotating platform. First, they assigned each letter a 5-digit number made of 0s and 1s, using the ASCII character encoding standard. Then, they adjusted each beam's attachment to the platform so that it would snap into one of its two stable positions (flipped to the left or right) at a different threshold of rotation parameters.
Meanwhile, the platform itself was connected to a high-torque motor to control its rotation. Depending on whether they reached their 'snap threshold', the beams would either remain in their original orientations or flip. By matching the final positions of all five beams to their corresponding binary pattern, the researchers could read out the letters they encoded.
"Motor technology, like the high-torque semiconductor motors we used, has only recently become powerful and precise enough to dynamically 'write' mechanical metamaterials in this way," notes co-first author Eduardo Gutierrez-Prieto.
Towards smart, remotely operated systems
The researchers are developing their dynamic driving method for real-world applications, and Reis emphasizes that the spinning platform demonstration is just one example of how rotation-induced forces can control mechanical metamaterials. In biomedicine, the power of centrifugal force could be harnessed to snap tiny bistable valves open or closed within centrifugal microfluidic channels, guiding liquids through diagnostic devices in a controlled, high-throughput manner. Likewise, electronics-free soft robots could be equipped with bistable joints that move in response to changes in air or water pressure delivered through pneumatic or hydraulic lines, enabling complex motion without onboard circuitry.
"Our dynamic control paradigm offers a versatile route towards smart, remotely operated devices that can function efficiently across a wide range of physical systems applications, from microfluidics and implants, to smart infrastructure and underwater or medical robotics," summarizes AMOLF researcher Martin van Hecke.
