BIRMINGHAM, England, Feb. 28, 2026 — Rice becomes weaker when compressed quickly, while staying stronger under slow pressure – a discovery enabling scientists to design a new material that could be used to build ‘soft’ robots that change stiffness automatically and protective gear that adapts to impact speed. 

Researchers harnessed this effect to design a new ‘metamaterial’ – an artificially engineered composite structure designed to behave in ways impossible for natural materials.

Publishing their findings in Matter, the international research team led by the University of Birmingham reveals that when packed rice grains are loaded at different speeds, their mechanical response changes dramatically.

This weakening at higher speed, known as ‘rate softening’, is not common in most materials. It occurs because friction between grains drops sharply at high speeds, weakening the internal force networks that normally support the load. 

They combined rice-based granular units with materials such as sand that strengthen under fast loading - creating a granular material that can bend, buckle, or stiffen differently under slow movements versus sudden impacts - without electronics, sensors, or active control.

Dr Mingchao Liu, from the University of Birmingham, said: “Rice might be best known as a staple food globally, but it’s rarely associated with advanced engineering. Our research shows that it can form the basis of a new class of functional materials.”

“Rather than treating this phenomenon as curiosity, we turned it into a design principle. This approach enabled us to create a material that can bend, buckle, or stiffen differently under slow movements versus sudden impacts - without electronics, sensors, or active control. Instead of telling a structure how to respond, we let physics decide: fast loads trigger one behaviour, slow loads another.”

More broadly, the work demonstrates how everyday granular matter can be transformed into engineered systems that respond intelligently through their intrinsic mechanics.

Such speed-sensitive metamaterials could enable novel solutions in soft robotics – creating machines that are lighter, safer, and more adaptable than traditional metal robots. This would make them ideal for working with humans, exploring harsh environments, and performing delicate tasks such as assisting with surgery. 

Working without electronics, power, or sensors, the material could also be used to create protective gear that adapts instantly to impact speed: absorbing energy or deforming safely under shock to protect the wearer from injury.

For more information, please contact the press office on +44 (0) 121 414 2772 or pressoffice@contacts.bham.ac.uk.