Preventing Concussions

A new football helmet could help players avoid brain injuries.

Head protection: A new football helmet developed by Xenith is lined with 18 thermoplastic airflow shock absorbers embedded in a flexible cap to better protect athletes from concussions. The helmet’s design adapts to the force of an impact and dissipates the energy to decrease the acceleration of the head and prevent the jarring that causes concussions. A transparent inside view of the helmet is shown at top, while the complete helmet is shown at bottom. Credit: Xenith

Xenith, a startup company based in Lowell, MA, has developed a new football helmet to better protect athletes from concussions. The helmet is lined with a thermoplastic material that can adapt to the force of impact. On a routine hit to the head, the discs cushion the head, while following a harder, more forceful blow, the material remains stiff and prevents the sudden jarring of the head that causes concussions.

"The idea is that we have something that is more intelligent and responds uniquely to what is happening to it," says Vincent Ferrara, the founder and CEO of Xenith. Testing has also shown that the discs can withstand hundreds of impacts without notable degradation in performance. The Xenith helmet will be available this spring for approximately $350, which is considerably more expensive than helmets already on the market.

The protective material in football helmets has evolved over time from traditional foam padding to gel-filled and inflatable padding. But Joseph Maroon, a neurosurgeon at the University of Pittsburgh Sports Medicine Center, says that none of the designs for football helmets are ideal, and concussions remain a common problem in the sport. "It is estimated that 10 to 25 percent of football players in the United States sustain a concussion each year, and the effects can be catastrophic," says Maroon, the team physician for the NFL's Pittsburgh Steelers. "There is a need for a new type of helmet technology."

To address this need, Xenith has embedded 18 shock absorbers into a flexible cap that lines the inside of a helmet. The shock absorbers are made out of a plastic that is elastic and flexible, thus it can accept a wide range of forces and return to its original shape instantaneously. The shock absorbers are hollow discs featuring a tiny hole to allow air to flow in and out. Upon impact, the walls of the discs collapse to absorb and dissipate the energy.

"When you force air or any fluid to flow through a small hole, you get an adaptive response: the harder [the disc] is hit, the stiffer it behaves, because you are generating more resistance inside the disc," says Ferrara. "You want a system to behave softly under low energy, but under high energy, you want it to get progressively stiffer so that it does not collapse down to nothing."

The inside lining of the Xenith helmet shown here is a flexible cap embedded with shock absorbers, or black discs, intended to dissipate the energy of a hit and lessen the sudden movement of the head that causes concussions.
Credit: Xenith

Conventional helmets are lined with different types of absorbency materials, such as foam or fluid-filled pads, intended to conform to the shape of the head and dissipate energy. Upon impact, the pads deform. However, the material lacks resiliency and thus degrades over time. Gel- and air-filled pads have to be refilled and monitored for leaks. What's more, these materials can't adjust to the amount of force.

A cable runs around the flexible cap from the back of the helmet toward the front, and through the helmet's chin straps. When a player pulls on the chin straps, the chin piece pulls the cable downward. This secures the back and sides of the helmet around a person's head, so the inside of the helmet is literally adapting to the person's head size and shape, says Ferrara.

The Xenith helmet is one more step in a football-helmet design that seems to be effective in absorbing energy and dispersing the impact so that it's not all going to the head, says Laurence Young, a professor of aeronautics and astronautics at MIT. Young is also working on a helmet design, still in the research phases, based on a similar concept.

The Xenith helmet will be available in one size this spring, and a full range of sizes will be released in 2009. Ferrara also plans to use the helmet technology in other sports helmets, as well as in military helmets.

http://www.technologyreview.com/Nanotech/20179/