Design, materials, engineering finding a faster way forward

AUSTIN, TEXAS — A year ago, U.S. Paralympics medalist Blake Leeper challenged members of the design community to help develop improvements to prosthetics.

Engineering and design specialists at Altair Thinklabs soon stepped up along with Eastman Chemical Co., and in just a few months they have already developed prototypes that would not just help Leeper shave time off his sprints, it also could help produce a better, more affordable athletic prosthetic for other amputees.

“Blake is an elite athlete, but we now have other concepts that could help the other 99 percent out there,” said Craig Mackiewicz, industrial design manager for Altair, at the Industrial Designers Society of America annual conference, held Aug. 13-16 in Austin. “We've been looking at other materials, like a fiberglass rather than carbon fiber to reduce costs.”

In addition to providing an update at this year's IDSA conference, Altair and Eastman are hosting a Sept. 10 webinar to discuss the project.

Leeper, who was born without lower legs, uses carbon fiber blades to compete in the 100 meter, 200 meter and 400 meter sprints and the 4-by-100 sprint relay. Since his first race in 2009, he has won a silver medal and a bronze medal at the 2012 Paralympic Games in London, and gold and silver in other international competitions. He was part of a record-setting relay team in 2013.

His goal is not just to compete in the Paralympic games in Brazil in 2016, but to represent the U.S. during the standard Olympic Games in Rio de Janeiro, competing against able-bodied athletes. To do that, he needs to shave about 4 seconds off his time in the 400-meter race.

Leeper grew up in Kingsport, Tenn., and Kingsport-based Eastman was an early supporter, bringing its expertise in materials to the table and giving him an early platform to address the public.

Altair brings with it not only product design capabilities, but extensive expertise in engineering and prototyping, with the ability to test Leeper's existing blades for performance and strength, but also do virtual testing of concepts.

“I am the only Olympian or Paralympian with a team like this,” Leeper said. “There's nothing else out there like this.”

Early on in the development process, Eastman and Altair hosted a “design storm” at the Art Center College of Design in Pasadena, Calif. — an intense 72-hour workshop to brainstorm ideas. During the session, students, engineers and designers were able to watch Leeper during a workout, talk to him about issues he had with fit and performance.

Each blade is made up of the carbon-fiber-reinforced blade itself, and the footpad with integrated spikes. The blade attaches to a specially-designed socket, which attaches to the stump of his leg. A neoprene sleeve fits over the stump, and a one-way valve provides suction to keep the blade attached.

In addition to studying Leeper's blades, Altair also made a set of “experience legs” so its team could get an idea of what it was like to just stand on blades, attaching snowboard bindings to an aluminum frame, which then attached to blades. Right away they realized how hard it was just to walk when you had no sensory feedback as to when your foot hits the ground.

They were able to quickly spot some issues, Mackiewicz said. The blades are symmetrical rather than having a “right” foot and “left” foot. That makes it hard to balance, while also affecting his performance.

“Blake's trying to turn left on the track, and he's been given two right legs,” said Kevin Shinn, vice president of design for Troy, Mich.-based Altair.

Altair's testing showed that he lost 40 percent of his power on the turns because of the effort of trying to make blades turn when they were designed to go straight.

The first concept blades reshape the blade and the footpad so they more closely resemble a normal foot and ankle. From Eastman's material portfolio, they pulled Tritan copolyester for a durable spike plate along with a thermoplastic elastomer in the foot area.

Eastman does not supply the materials used in the bulk of the blade, but its chemical engineers can point the project team in the right direction.

For instance, to improve aerodynamics — Leeper hits 23 mph on the backstretch in a 400-meter race — Eastman pointed the group to Vectran, a liquid crystal polymer fiber made by Japan's Kuraray Co. Ltd., and typically used in aerospace. The Vectran would cover the blades to reduce friction. Altair's virtual wind test simulations showed it reduced drag by 57 percent compared to existing blades, which translates to a half-second faster over the distance, Shinn said.

And then there is just the issue of keeping the blades attached, Shinn noted.

During a workout, Leeper sometimes has to stop and take off his blades to empty out the sweat that has collected in the sockets, moisture which disrupts the vacuum that keeps the legs attached to him. At one race, Leeper said the one-way air valve failed just before the start, and as he ran he not only had to think about his coaching and the race, but also wonder if his leg would fly off.

“That is something no able-bodied athlete has had to deal with,” Shinn noted.

To combat that, the design group has developed a prototype suit — the F1 — which uses TPU strategically to connect the blades to the runner, all the way up to his shoulders, securing the blades and allowing the runner to concentrate on the race and not the blades.

Other, less expensive offshoots of the F1 could an attachment using a pair of shorts, so an amputee could attach a prosthetic with the same sense of security, he said.

“Not everybody wants to compete in front of 85,000 people,” Leeper said. “Some of them just want to play with their kids.”

Shinn admitted that the development team does not know what kind of commercialization the research could lead to, but believes there is a demand out there. The “Road to Rio” project is just laying the groundwork for potential future developments that can serve more people.

“We look at Blake like you would a concept car. Not everything that [automakers] do in a concept car is going to trickle down, but some of it will,” he said. “Just like sporting equipment today. There may be one level of products for the elite athlete, but there are always going to be the average athlete who wants part of that.”

The prototypes the team now has are just the result of four-and-a-half months of study and development. The team will have to work fast, though. Trials for the U.S. 2016 Olympic team are in July 2016, and Leeper will need time to adapt to any new equipment well in advance of that.

In addition, the development team has had to continually check that any equipment Leeper has meets the requirements allowed in competition by the Olympics and U.S. Track & Field.

“The power of design is to know that you can help someone fix their life,” Leeper said, “not only my life, but this will help thousands of other amputees.

“We have no clue where this is going to take us.”