Foam and Football


BYU student Jake Merrell created a smart foam that can be inserted into football helmets to measure the impact of hits. Image:

Brigham Young University’s mechanical engineering grad student Jake Merrell is a football fan, but he had his doubts about how long the game could survive with its concussion situation. With the NFL and sports apparel firm Under Armour offering millions in grant money for those who can come up with a solution, Merrell has his own innovation to throw into the mix.

“It started when I was an undergrad,” he says. “I was part of a lab working on self-sensing foam. We put nanoparticles into silicon and created resistance material. I asked, ‘What if we could measure negative strain?’ I wanted to see if that would be a good avenue for nanoparticles for piezoresistance foam. I got it to be conductive but on 50 negative megaohms—it’s very hard to read.”

Then, through other testing, Merrell put a volt meter on it and saw a voltage coming out of it by accident. “I found it was piezoelectric and the properties of piezoelectric are more appealing than piezoresistance,” he says. “Piezoelectric doesn’t drift with time like the resistant version. I was thrilled because it has consistent output and doesn’t require as much power to monitor it.”

An early version of the smart foam Jake Merrell is developing. Image:

Classifying Signals

Next, it was time to try to classify the signal coming out of the foam. “I started playing with it and doing it at certain strains at a certain frequency and I changed the frequency,” he says. “The signal changed with the same amount of strain, so it’s not just strain dependent but strain rate dependent as well.”

Merrell felt it was perfect for helmets but didn’t want to know just the acceleration experience but the force it experiences as well. “I did impact testing and found the output and the voltage that foam creates is directly correlated to both force and acceleration. So we can get a lot more information out of the impacts. I started benchmarking and saw what other sensors were out there. The others use gyroscopes in combination with accelerometers to measure impact forces. It can be better.”

To this point, he’s measured impacts such as getting a helmet hit with a baseball bat and ramming one into the wall. “The baseball bat acceleration is the same in magnitude as hitting your head against the wall but the bat doesn’t get any output because the force isn’t large enough—not as much mass," he says. "Slamming your head gets a spike in the output because there’s enough force to cause enough reaction.”

But a game scenario could be better than a wall, Merrell says. “We are getting to the point where we’re meeting with trainers and maybe going to use it in a BYU football spring practice,” he says. “The response has been very positive.”

BYU student Jake Merrell tests his helmet smartfoam product with a football player. Image:


Analyzing Results

Now working on the foam for his thesis, Merrell is even licensing it from the university. “We’re creating proprietary software that can analyze these impacts and have it go over the web so it’s accessible in different locations,” he says. “You want a coach in the box to see the same information as what a person on the sidelines can.”

Still, this can potentially go beyond football, Merrell says. From shin guards, to boxing gloves, to shoulder pads, even crash test dummies. “It could even possibly help running by measuring how shoes deal with impact," he notes. "It might save knees.”

But the biggest goal for now will be the gridiron, and he is actually thinking of the youngest level. “We want to get this into pee wee football,” he says. “If we can measure how many hits someone takes from the start, we can know if they’re in trouble early. It’s a great game but you don’t want to see permanent damage happen if it can be avoided.” 

Eric Butterman is an independent writer.

If we can measure how many hits someone takes from the start, we can know if they’re in trouble early.

Jake Merrell,
Brigham Young University


November 2013

by Eric Butterman,