Smart Helmets Monitor Athletes' Head Injuries

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December 22, 2003 (3:04 PM EST)

Smart Helmets Monitor Athletes' Head Injuries

Park Ridge, Ill. - As visions of sugarplums give way each holiday season to bone-crushing bowl games, college football coaches fret about head injuries. This year, Virginia Tech is acting on its concerns. The Blacksburg, Va., university's football team has outfitted its helmets with sensors, microprocessors and RF transceiver chips that can help tell how hard the players are getting hit. Ultimately, the engineers behind the project hope the technology will pave the way for the development of systems that could quickly spot dangerous head injuries in college, high school and even youth football programs.

"When a player gets a concussion and doesn't realize it, he's susceptible to sustaining another impact that could be fairly dangerous," said Jeffrey Chu, research engineer at Simbex LLC (Lebanon, N.H.), a maker of the biomechanical-feedback system used in Virginia Tech's helmets. "Eventually, a device like this could alert the medical staff, parents or coaches that the player has taken a hard hit."

Virginia Tech, which will play in the Insight Bowl in Phoenix on Friday, has been using the technology since the beginning of this football season. Its effort, supported by funding from the National Institutes of Health, involves a biofeedback system installed in eight helmets that are used by 38 different players. Over the course of the season, the university has collected data on more than 3,000 high-impact collisions from those 38 athletes.

"We're looking at how accelerations predict head injuries," said Stefan Duma, director of the Center for Injury Biomechanics in Virginia Tech's department of mechanical engineering. "Concussion is an internal tissue failure in the brain, and it's caused by acceleration."

The device for monitoring injuries, the HIT (Head Impact Telemetry) System, is placed in football helmets so as not to distract the players. This "electronic brick" consists of six linear accelerometers from Analog Devices Inc. (Norwood, Mass.) and two tiny printed-circuit boards, one containing a microcontroller and another incorporating an RF transceiver.

"When a player sustains a head impact, it triggers all six accelerometers, and the system saves data locally in the helmet," Chu said. "If RF communication is available, it then downloads the data to a receiver and computer."

Spring-loaded buttons in the accelerometers are always in contact with the player's head. When the head receives a hit that exceeds a prescribed impact of 10 g's, the buttons are depressed and the accelerometers send the "hit data" through a set of wires connected to a 20-pin microminiature insulation-displacement connector from Samtec Inc. (New Albany, Ind.) on the processor board. That 1 x 3-inch board incorporates a Hitachi H8 microcontroller, a 10-bit analog-to-digital converter, 16k of on-chip RAM and 128k of flash memory. Developed for the application by engineers at Microprocessor Designs Inc. (Shelburne, Vt.), the board filters the accelerometer signals and then sends them to the Hitachi microcontroller.

The microcontroller then communicates in serial fashion with a separate board housing an RF transceiver from Lab Partners Associates (South Burlington, Vt.). Operating in the 902- to 928-MHz frequency range, the transceiver sends the hit data from the helmet to a receiver located on the sidelines, which shares the data with a laptop computer. The laptop, incorporating a dynamic-link library from Microprocessor Designs and higher-level application software written by Simbex, extracts information about the magnitude, duration and location of the impact. It then displays that data, complete with three-dimensional graphics of the human head and indicators to show where the player was hit.

Engineers from Microprocessor Designs, which did the hardware and firmware design, said one of their toughest challenges was putting the HIT System in a standard helmet. "Simbex wanted the system to be retrofitted into an existing helmet and they didn't want the user to notice any hardware or heavy batteries," said company president Jeff Finkelstein.

To power the system discreetly, engineers chose two off-the-shelf AAA nickel-metal-hydride batteries. "Players needed to be able to take the helmet from the locker room to practice, and then to a game, so they needed to get eight hours of operation from a single charge," he said.

Hit 'em again, harder

Using the smart helmets, researchers at Virginia Tech say they want to gain a wealth of knowledge about the causes of head injuries. By looking at accelerations of the head, they say they can better assess concussions and similar trauma. "Your brain is a soft tissue and when you accelerate it, you can exceed its ability to move that fast," said Duma of Virginia Tech. "That's when you damage the tissue."

The researchers have tracked accelerations exceeding 100 times the acceleration of gravity (100 g's). By tracking such violent impacts and subsequently doing clinical observations of players, they expect to obtain information that has never before been available.

"In the past, we put helmets on dummies and tried to re-create forces, but that's essentially guesswork," Duma said. "This is the first study to go out in a real game and measure what the head sees."

Much of the effort has been spurred by the knowledge that many athletes continue to play after sustaining concussions, often staying on the field when they don't know where they are or what day it is. A case in point, the researchers said, was a highly publicized incident earlier this year when St. Louis Rams quarterback Kurt Warner remained on the field after sustaining a serious concussion.

Engineers said the knowledge gained from the HIT System could be used by helmet engineers, as well as by physicians and team trainers. Equally important, the engineers hope to bring the technology down to lower-level football programs, where it could be used in real-time to monitor young athletes.

"It would be very easy to work this into a wireless system that would page the trainer on the sidelines after a hard impact," Duma said. "Then the trainer could watch the player to see if he needed to leave the field."

To do that, however, costs would have to drop. The prototypes cost about $2,000 per helmet, but engineers said the system's price could realistically fall to less than $100 with sufficient volume. "Our goal is to trickle the technology down to the high school and youth level," said Chu of Simbex. Chu said the company also foresees its use in hockey and in "unhelmeted" sports such as soccer, where sensors could be placed in headbands to tell if a player sustained a concussion while "heading" the ball.