STANFORD, Calif. — The moment Stanford wide receiver Chris Owusu collided with a defensive back at Oregon State last week, information about the severity of his head injury started to emerge on the sideline.

Not from a trainer or doctor, but rather from a sensor in his mouthpiece relaying data through a wireless transmitter for instant analysis. The detailed diagnosis went beyond a simple screening, giving insight on an injury that will sideline the starting receiver when No. 3 Stanford faces No. 6 Oregon on Saturday night.

In an unprecedented field research study, about two dozen Stanford players are wearing mouthpieces equipped with tiny sensors to measure the number and force of head impacts during games and practices. The sensors provide instant information to the sideline, where team trainers and doctors monitor hits as they happen.

"If you go back and look at the four-year career of a collegiate football player, how many hits are they actually receiving? That's what we want to find out," said Dr. Dan Garza, Stanford's team physician and assistant professor of orthopedic surgery. "And, secondly, is there a threshold for concussions? Or is there at least a zone where we say this is highly likely going to be a concussion? Maybe we can alert players to that ahead of time."

Even with the football team gaining unprecedented notoriety, real-world issues at Stanford come first.

The mouthpieces are slightly thicker than the normal ones, and they offer the same protection. The difference is the devices contain accelerometers and gyrometers that measure the linear and rotational force of head impacts, and a radio inside transmits the data to sideline computers.

Stanford researchers dropped a crash-test dummy some 4,000 times to ensure the sensors corresponded to what the brain is experiencing from the mouth. The study is being funded by the Stanford Department of Orthopedic Surgery with support from the athletic program.

Garza presented 24 mouthpieces to the team and explained how they functioned before the season. Players were not asked to participate — they could decide on their own.

The response has been so overwhelming that there are more players asking for the devices than ones wearing them.

Players have been partners in the study, providing feedback on the devices and how to improve technology. The responses so far have differed.

Stanford quarterback and Heisman Trophy favorite Andrew Luck doesn't wear one because the enlarged mouthpiece is bothersome and causes him problems when he's calling out cadences. Others prefer it because it keeps their mouths open and helps them breathe easier.

"At first, I just wanted to wear it because it lights up and glows in your mouth," said safety Michael Thomas, one of the players to volunteer for the research. "I was like, 'Wow, that looks cool.' But it's definitely contributing to something great."

Others hardly notice a difference.

"I don't really think about it while I'm playing," wide receiver Ty Montgomery said. "At the end of the day when the trainers are reminding me what it does, it kind of feels good that I'm part of something like that. It just reminds me how special this place is."

Concussions have become a major issue in sports in recent years.

The NFL, NHL and college football, among others, have implemented stricter rules on hits to the head and player safety. While dizziness or memory loss is often associated with concussions, symptoms are not always easy to detect.

Kevin Guskiewicz, a professor of sports science at North Carolina and a concussion expert, has done research on helmets with built-in accelerometers. The mouthpiece sensors involve similar principles, and could provide more insight, with the hope to spread the devices to other sports where players don't wear helmets.

The mouthpiece is manufactured by a Seattle-based company called X2 Impact, which has provided the devices on loan for research. Christoph Mack and Rich Able started the company from their garage in 2007 after Able's son, Kyle, was knocked unconscious in a high school football game.

Now they can't even keep up with demand.

The mouthpiece has been introduced to about a half-dozen other major college football programs and at least one NFL team, Mack said. Stanford is the only one conducting field research and has an internal review board studying the results.

"I firmly believe concussions are an issue that will be solved with information and knowledge, not helmets," said Mack, president and CEO of X2 Impact, whose product is manufactured by Bite Tech.

The study at Stanford is still in its infancy.

Football players have only been wearing the devices for a little more than 10 weeks, and it could take years of analysis to develop ways to improve safety. Stanford researchers hope to order enough mouthpieces for the entire roster next year and increase the study to the field hockey and lacrosse teams.

The football team's unprecedented success — 17 straight victories going back to last year — has certainly helped spread the word.

"This is a very big year for Stanford. I think there's a lot of pressure on the kids. But they are unbelievable in terms of their willingness to help," Garza said. "We can't ask them to do a favor. They're amazing kids. For a school that's having the best season in history, to be doing ongoing research like this, I don't think you're going to get this at a lot of places."

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Follow Antonio Gonzalez at: www.twitter.com/agonzalezAP