A humanoid robot works in an office on a laptop. demaerre/iStock
Human progress has always depended on the ability to store and release energy efficiently.
Springs, buffers, and energy-damping materials power everything from industrial machines to futuristic robotic limbs.
Now, a breakthrough from scientists at the Karlsruhe Institute of Technology (KIT) is pushing energy storage technology to the next level.
They have developed a new class of mechanical metamaterials—artificially engineered structures that store and release elastic energy more efficiently than ever before.
This innovation could lead to major advancements in energy-efficient robotics, mechanical systems, and flexible structures that maximize energy use while maintaining strength and durability.
These materials use a unique structure of twisted rods that deform in a helical shape, allowing them to absorb and release large amounts of elastic energy.
By leveraging this novel design, researchers have created a material that combines high stiffness, high strength, and exceptional flexibility.
What are mechanical metamaterials?
Metamaterials are specially engineered materials designed to have properties that don’t exist in nature.
They are made by arranging tiny structural elements in precise ways to create materials with enhanced mechanical behavior.
In this case, the KIT researchers developed a mechanical metamaterial built from rods that are tightly twisted and arranged in a specific pattern.
Normally, when a spring bends, stress builds up at its top and bottom surfaces, which can lead to breaking or permanent deformation.
However, twisting a rod instead of bending it spreads the stress more evenly across its surface. This means it can store more energy without damage.
Peter Gumbsch, Professor for Mechanics of Materials at KIT’s Institute for Applied Materials (IAM), explained, “The difficulty is to combine conflicting properties: high stiffness, high strength and large recoverable strain.”
By carefully arranging these twisted rods into a structured network, the scientists created a material that can store far more energy than traditional materials while remaining strong and stiff.
Designing a material with maximum elasticity
Gumbsch and his team, which includes researchers from China and the U.S., successfully translated this concept into a functional metamaterial.
“At first, we detected a mechanism for storing a high amount of energy in a simple round rod without breaking it or deforming it permanently,” said Gumbsch.
“By defining a clever arrangement of the rods, we then integrated this mechanism into a metamaterial.”
By aligning the rods in a precise way, the researchers created a material that could be stretched or compressed while still returning to its original shape.
Computer simulations predicted that this metamaterial would have high stiffness and could handle large forces.
Their tests confirmed that the material’s energy storage capacity, or enthalpy, is between 2 and 160 times greater than other known metamaterials.
Helical deformation of the new metamaterial. – IAM, KIT / Collage: Anja Sefrin, KIT
Future applications in robotics and energy storage
The potential uses for this new type of material are vast. “Our new metamaterials with their high elastic energy storage capacity have the potential to be used in various areas in the future where both efficient energy storage and exceptional mechanical properties are required,” said Gumbsch.
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Robots could become more flexible and durable, benefiting from the material’s ability to stretch and recover without breaking.
Additionally, energy-efficient machines could store and release energy more effectively, improving overall performance.
Another possibility is using the twisting mechanism within the metamaterials to create purely elastic joints, removing the need for traditional hinges and improving motion in robotic limbs and wearable exoskeletons.
With these advancements, mechanical metamaterials could pave the way for stronger, more efficient, and longer-lasting technology.
The study is published in the journal Nature.
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ABOUT THE EDITOR
Aamir Khollam Aamir is a seasoned tech journalist with experience at Exhibit Magazine, Republic World, and PR Newswire. With a deep love for all things tech and science, he has spent years decoding the latest innovations and exploring how they shape industries, lifestyles, and the future of humanity.
