Stanford bioengineers have developed a device that could one day provide real-time measurements of the head impacts sustained by football players. Another benefit of the research is that it could help characterize the forces sustained in more common head traumas, such as car accidents and falls.
David Camarillo, an assistant professor of bioengineering, and his colleagues have been supplying Stanford football players with special mouthguards equipped with accelerometers that measure the impacts players sustain during a practice or game. Previous studies have suggested a correlation between the severity of brain injuries and the biomechanics associated with skull movement from an impact. According to Camarillo, “We are instrumenting Stanford athletes with inertial sensors to investigate the mechanism of concussion. The mouthguard to the left is worn by Stanford football players and women’s lacrosse to measure the “dose” of impact. We are also characterizing the response of head-blows through imaging, blood, and other neurophysiological measurements. Understanding the mechanism of concussion will allow for change of rules, technique, or the development of preventive equipment and diagnostics to reduce brain injuries”
Camarillo’s group uses a sensor-laden mouthguard because it can directly measure skull accelerations – by attaching to the top row of teeth – which is difficult to achieve with sensors attached to the skin or other tissues. So far, the researchers have recorded thousands of these impacts, and have found that players’ heads frequently sustain accelerations of 10 g forces, and, in rarer instances, as much as 100 g forces. By comparison, space shuttle astronauts experience a maximum of 3 g forces on launch and re-entry.
According to the report, these mouthguards have provided a wealth of data, they were not very discerning: A player tossing his mouthguard to the ground can register the same force as if he had been run over by a linebacker. This has required Camarillo’s team to spend hours going through videos of games and practices to determine whether each player’s time-stamped data matches a true impact or a spurious event, said Lyndia Wu, a bioengineering doctoral student in Camarillo’s lab and the lead author on a new research paper, published recently in IEEE Transactions on Biomedical Engineering.
To overcome this dilemma, the researchers incorporated infrared proximity sensors into the mouthpiece, so that it can detect when the device is firmly seated against the player’s teeth. Furthermore, machine-learning algorithms sift out additional “noisy” signals to only focus on real impacts.
Wu said that both of these improvements make it faster to collect data, which will become critical for expanding research to other subject populations and collecting a larger data set to ultimately prove what specific aspects of head acceleration cause concussions.
“We do know that sustaining a second injury right after the first injury will exacerbate the trauma, so detecting that injury is critical,” Wu said. “However, diagnosis often relies on players to self-report injuries, which doesn’t work often for a variety of reasons. A player typically shakes it off, thinking he will be fine, without telling the coaches or trainers. Eventually, we hope to have a device that is able to screen for injury in real time.”