Nelson Sepúlveda was sitting in the stands at Spartan Stadium, watching his hometown Michigan State players bash heads with their cross-state football rivals from the University of Michigan, when he had a scientific epiphany.

Perhaps the nanotechnologies he had been working on for years—paper-thin devices known as ferroelectret nanogenerators that convert mechanical energy into electrical energy—could help save these athletes from the ravages of traumatic brain injury.

An electrical engineer at MSU, Sepúlveda had made self-powered loudspeakers, flexible microphones, and e-textiles out of his miniature, energy-harvesting platform. Now he wanted to apply the technology to the problem of concussion monitoring.

The Spartans lost 21–7 to the Wolverines on that October afternoon in 2018, but Sepúlveda left the stadium with a winning idea.

“There is a lot of scope to piezoelectric-type sensors for measuring movement and providing feedback to people.”
—Andrew McIntosh, Monash University

“I think it’s the best application that we’ve found so far for this [technology],” he says.

Existing concussion safety protocols dictate that players involved in on-field collisions must undergo medical evaluation for symptoms of head trauma before returning to action, but this system is easily manipulated—and it overlooks many of the subconcussive blows that can collectively cause long-term effects on the brain.

Sensor-laden helmets and mouthguards exist that gather accelerometry data for a more quantitative measure of impact forces to the head. However, helmets can slide around, and mouthguards often get chewed up. So these embedded sensors do not always offer an accurate picture of what’s happening inside the skull—or even if someone has truly had their bell rung.

“You end up with a lot of false readings,” says Sepúlveda. A better option, he thought, would be a wearable patch applied directly to the skin around the neck.

Sepúlveda and his students kitted out crash-test dummies with four of their piezoelectric devices—one on the throat, one on the nape, and one on each side of the neck. They performed simulated whiplash experiments on the dummies, and found that the Band-Aid–size patches accurately captured indicators of brain injury.

The sensors transformed tensile strains applied to the neck into voltage pulses. And that electrical output proved highly predictive of rotational forces deep in the head, as measured by accelerometers implanted inside the dummies’ noggins.

Sepúlveda and his colleagues published their findings in the journal Scientific Reports. With an eye to commercial applications, the researchers are now adapting their sensors for wireless data transmission. They are also encapsulating the devices in protective materials that shield the technology against sweat and other grime. Trials in human athletes should follow.

Sepúlveda points to several potential benefits of his neck-sensor system over the kinds of intelligent helmet and mouthguard technologies that the National Football League and other sports associations are beginning to adopt. [READ MORE]