July 14, 2023
The discovery that football players were unknowingly acquiring permanent brain damage as they racked up head hits throughout their professional careers created a rush to design better head protection. One of these inventions is nanofoam, the material on the inside of football helmets.
Thanks to mechanical and aerospace engineering associate professor Baoxing Xu at the University of Virginia and his research team, nanofoam just received a big upgrade and protective sports equipment could, too. This newly invented design integrates nanofoam with “non-wetting ionized liquid,” a form of water that Xu and his research team now know blends perfectly with nanofoam to create a liquid cushion. This versatile and responsive material will give better protection to athletes and is promising for use in protecting car occupants and aiding hospital patients using wearable medical devices.
The team’s research was recently published in Advanced Materials.
For maximum safety, the protective foam sandwiched between the inner and outer layers of a helmet should not only be able to take one hit but multiple hits, game after game. The material needs to be cushiony enough to create a soft place for a head to land, but resilient enough to bounce back and be ready for the next blow. And the material needs to be resilient but not hard, because “hard” hurts heads, too. Having one material do all of these things is a pretty tall order.
The team advanced their work previously published in the Proceedings of the National Academy of Sciences, which started exploring the use of liquids in nanofoam, to create a material that meets the complex safety demands of high-contact sports.
“We found out that creating a liquid nanofoam cushion with ionized water instead of regular water made a significant difference in the way the material performed,” Xu said. “Using ionized water in the design is a breakthrough because we uncovered an unusual liquid-ion coordination network which made it possible to create a more sophisticated material.”
The liquid nanofoam cushion allows the inside of the helmet to compress and disperse the impact force, minimizing the force transmitted to the head and reducing the risk of injury. It also regains its original shape after impact, allowing for multiple hits and ensuring the helmet’s continued effectiveness in protecting the athlete’s head during the game.