When Army veteran Russ Hubbard's uncle fell from the balcony of his home in the Caribbean in 2011 and broke his back, Hubbard helped move him to Tennessee so family could help take care of him.
After Hubbard's uncle reluctantly began the physical therapy process, the Army vet started noticing some deficiencies.
As a result, Hubbard, who is also a small business owner, started looking at other options and stumbled across the rate-activated tethers Dr. Eric Wetzel and his team at the Army Research Laboratory (ARL) had been developing.
In 2000, when Army researchers started studying shear thickening fluids, which are speed-sensitive materials, Wetzel said he didn't know exactly what they were going to be used for in the future. It wasn't until about five years ago that ARL started trying to incorporate the material into a strap, which they now refer to as a rate-activated tether.
"They are elastic straps that are flexible and stretchable, but their resistance to stretching is speed-dependent," Wetzel explained.
The rate-activated tethers consist of an elastomeric tube that contains the shear thickening fluid. When the tethers are stretched at low speeds they react like a rubber band, but at high speeds, they become 10-100 times more resistive.
The Army Research Lab patented the device in 2016 and when Hubbard first approached researchers with the idea of incorporating it into physical therapy devices, Wetzel admitted he "didn't quite see the connection at first."
"The more and more he [Hubbard] talked to me about it, I realized there is a very strong connection there," Wetzel said. "For example, the response of these tethers is speed sensitive, so depending on how fast you pull it, you get more and more resistance. Therefore, you can tailor your workout or your therapy based on how fast you’re pulling it."
Now, with the help of DoD TechLink, which helps connect private industry to new inventions from Department of Defense labs, the Army Research Lab has licensed the technology to Hubbard's Tennessee-based company, Per Vivo Labs.
"There’s a lot of unique characteristics to it that allow for exercises or movements to be done in a way that have never be done before."
Hubbard's company is now looking to incorporate the technology into a number of devices that he said could "fundamentally change the way practitioners can assist their patients."
"There’s a lot of unique characteristics to it that allow for exercises or movements to be done in a way that have never be done before," Hubbard added.
One of the possibilities Hubbard mentioned was incorporating the technology into a sling for patients with broken arms.
"By utilizing the tether, you can provide resistance that would allow the patient to move their arm so the muscle doesn’t necessarily atrophy, but at the same time if there is a sudden shocker movement, the behavior of the material would essentially become a solid and thereby be like you just had a regular sling on," he explained.
Still, this is likely just the beginning for this technology.
Wetzel and his team previously received a series of grants for the NFL in partnership with GE and Under Armor as part of the Head Health Challenge, which is a program aimed at developing new technologies to address head and brain injuries in sports.
As part of that, ARL researchers explored using the tethers as "shock absorbers between the head and the body, where the speed sensitivity is key."
"So because our straps are speed sensitive, we can couple the head to the body, allow free motion at lower speeds and only at very high speeds do the straps kick in and prevent that head from really thrashing around and potentially causing injury," Wetzel explained.
Wetzel said his lab is very good at understanding science and inventing new technologies, but working with companies like Hubbard's is what really bridges the gap between a cool technology and something that's practical for the marketplace.
Although Wetzel said it's difficult to predict the real-world potential applications for this material, he's certain that because it's different, "applications will find it."
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