Breakthrough Reebok Sports Bra Transforms Market with Innovative UD Technology

Actress #nathalieemmanuel models the Reebok PureMove sports bra developed at the University of Delaware

When a Reebok apparel designer learned of a technology developed at the University of Delaware, she thought it might lead to a major game-changer for female athletes: a sports bra that combined flexibility under stress and comfort.

The UD-born technology is called Shear Thickening Fluid, or STF, which gets stronger under pressure and was originally designed for body armor, puncture resistance and protective surfaces. 

Invented by UD professor Norm Wagner and university graduate Eric Wetzel, STF caught the eye of Danielle Witek, then a senior innovation apparel designer for the global footwear and athletic gear giant Reebok, while she was browsing a scientific journal.

After much testing and collaboration with a range of UD researching from fields spanning engineering and kinesiology, Reebok’s PureMove sports bra and a whole new franchise were born.

The product quickly took off, landing on Time Magazine’s list of the 50 Best Inventions and Popular Science’s list of the 100 Greatest Innovations of 2018.

“It’s turning out to be our largest apparel launch ever,” says Witek. “The response has been overwhelmingly positive – better than we could have expected or hoped for.”

None of this was in the plan five years ago when Wagner and another UD alum, Rich Dombrowski, started their business, STF Technologies. NASA uses the same product in their spacesuits.

L to r: Norman Wagner, Richard Dombrowski, Erik Hobbs and Lauren Piascinski of STF Technologies LLC in 2014. Image courtesy of UDaily

“If you had said that the first product launched using this technology was going to be a sports bra, I don’t know that I would have believed you,” Dombrowski said.

According to Reebok, half of the women who exercise experience breast pain, and 70 percent report a poorly fitting bra. One in five women says the problem of discomfort is an obstacle to regular exercise for them.


STF is made of tiny particles, suspended in liquid. When that liquid is hit with sudden pressure or impact, the particles instantly connect, forming strong, solid layers. Later, as the energy from the impact dissipates, the particles move back into suspension as a liquid.

According to UD, these unique properties have led to two NASA contracts with STF Technologies to protect astronauts and fabrics infused with STF are flying outside the International Space Station now. The Department of Defense and law enforcement agencies are exploring various uses of STF combined with Kevlar.

After reading the journal article Witek reached out to UD, wondering if the technology could help female athletes.

#reebokindia. Image from #puremovebra – Instagram.

“I cold-called them,” she said. “Could this be integrated into a soft performance fabric? I thought they’d think I was crazy, but they gave it good thought.”

Wagner, who is a chair in the chemical and biomolecular engineering department and a faculty member in UD’s Biomechanics and Movement Science graduate program, took the call and quickly engaged the expertise of Jim Richards, a professor in the Department of Kinesiology and Applied Physiology in UD’s College of Health Sciences.


Richards and his colleague Elisa Arch’s expertise in the study of human motion have made them sought-after advisers to Olympic athletes, including competitive skaters, who want to have the biomechanics of their jumps evaluated.

The UD team developed a new biomechanics testing process, placing 56 markers on sports bras of many kinds to track how the fabric responded to the motion of humans of varying sizes.

They recruited females to wear the necessary data-gathering gear and soon delivered unprecedented insights—precise calculations on where, when and how the fabrics in these runners’ bras were moving, stressing and stretching, where support was needed and when.

Graduate students helped with the research and Richards put the data into context.

“He is a wizard with the way the data is represented, providing it in a way that’s easy to digest,” Dombrowski said of Richards. “He wrote custom code and we got a lot of visualization, a lot of video.”

The engineers at STF Technologies then developed a solution to create a fundamentally new “movement reactive fabric” that provided the necessary support.


“Areas where we saw a lot of motion wound up being the focus of design,” Arch said. “And they were able to control that motion much better.”

Finding the right fabric and engineering all of the necessary features were major challenges.

Richards and Arch tested the prototypes and reported the results.

UD researchers applied biomechanics to capture soft tissue motion in their development if a new sports bra

“Our testing showed that it had potential,” Dombrowski said. “And once you start putting it on people—that’s when it really clicks. We tested 10-15 competitor products, ran the biomechanics and we had some prototypes that were outperforming everything on the market today.”

Soon a new “smart” sports bra, the $60 PureMove with Motion Sense Technology, was born. It launched in August 2018. On its website, Reebok describes the bra as “an innovation that simply adapts to your movement, like an external skeleton.” 

See a UD video demonstrating the technology


“We could not be prouder to come to market with a product that breaks down barriers in a category that has dissatisfied customers for far too long, lacking any true technological advancements,” Barbara Ebersberger, Reebok’s vice president of performance apparel, said at the product’s launch.

“We have turned it into a franchise,” said Witek. “It’s not a one-off product. We’ll evolve it.”

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