Progress in various areas depends on the best quality of materials. Now a new class of “scale-rich metamaterials” has been developed by introducing a controlled perturbation inspired by natural networks such as leaf vessels and dragonfly wing veins.
Engineers have strived for mathematical perfection for decades in developing synthetic “metamaterials,” mimicking identical microscopic building blocks to create rigid honeycombs and lattices. A new collaboration between MIT and Northeastern University just proved that a little chaos works much better.
Physical testing has shown that these irregular materials better resist impact, provide adjustable stiffness, and protect fragile embedded objects.
This technology could spur the development of safer sports helmets and lightweight body armor. It could also enable precise acoustic lenses that control sound waves and vibrations with high precision.
Little mess when producing synthetic materials
The research introduces “scale metamaterials.” These synthetic structures abandon uniform grids and become chaotic, sprawling physical networks modeled on the vascular systems of leaves, neural connections, and even the Internet.
Uniform metamaterials share a common vulnerability. When a single cell in a repeating grid ruptures or punctures, the surrounding identical cells immediately follow suit, resulting in a chain reaction collapse. Carlos Portela, an associate professor at MIT, and his team wanted to fix this localized error, so they teamed up with Northeastern physicist Albert-László Barabási, a pioneer in network science.
Barabási has spent his career mapping invisible networks – from social media links to financial markets – to understand how networks resist collapse. Together, the researchers transformed these abstract mathematical rules into tangible, physical matter.
The team wrote an algorithm that generates a virtual blueprint for a material without using a single repeating pattern. The program chooses a random point in space and draws a line across the entire domain.
The press release says it then selects a second random point and draws a line that stops once it hits the first line or an outside edge. Repeating this process thousands of times creates a dense, network-like architecture of intersecting support beams of completely different sizes and thicknesses.
Scientists can adjust the stiffness of a material by simply adjusting two parameters in their algorithm: the thickness of the initial line and how quickly subsequent lines become thinner.
After simulating these variations, the researchers 3D printed credit card-sized polymer samples with interconnect beams ranging from micrometers to centimeters.
Furthermore, physical tests confirmed that these chaotic networks outperform conventional ordered materials across the board. The scale-rich designs absorbed sudden, violent impacts without bending, offered a tremendous range of adjustable stiffness, and successfully cushioned delicate objects deeply embedded within them.
“This is a whole new way of thinking about metamaterials,” Portela said. “Unlocking this network design for materials really gives us the freedom to think about new microstructures and mechanical advantages that weren’t possible before.”
In practical applications, manufacturers could soon use the algorithm to print next-generation sports helmets, lightweight body armor, and precision acoustic lenses that focus sound waves and vibrations with unprecedented control.
The results were published in the journal Nature.
