There are certain things prostheses allow amputees to do every day – like walking. But Kai Lin, industrial design student at the Pratt Institute, thought they should allow something more – like climbing near-vertical rock faces.
‘I wanted to create something’
“When I was researching [ways to do this], I came across a YouTube video of goats climbing a dam in Italy,” Lin told O&P Business News. “I was inspired … by how they could easily climb steep surfaces.”
It turns out that mountain goats are some of nature’s most sure-footed climbers. Their uniquely structured hooves provide traction, enabling them to scale mountainsides without so much as a misstep.
Current prostheses do not share that anatomy. They do not have tiny feet for latching onto rock, ridged outer shells for stable footing on cliffs or sensory feedback for natural control – but Lin is working to change that.
“I saw an opportunity in this field … and asked, ‘why don’t I create a prosthetic leg for those who are rock climbing?’” he said. Specifically for rock climbers returning from war, he added.
“These soldiers often suffer from physical and mental trauma … [and] many do demanding sports as a method of coping,” he said. “Rock climbing is their top choice, and I wanted to create something to help them do that.”
Images: Lin K.
So Lin started creating. By way of his aesthetics of prosthetics senior design class, his first stop was a Philadelphia-based rock climbing gym.
“I interviewed climbers who were experienced [in the sport]. I wanted to understand how they used their bodies to perform different techniques.”
Lin recorded these findings in his project portfolio, and then he took to the rock wall himself.
“I had to see how it felt [to climb] without feedback,” he said. “But since I do not wear a prosthesis, I attached blue foam stilts to the bottom of my feet.”
He tested the stilts in different sizes and found that when the surface of the foot is too big, it could block the underneath view of the wall; when it is too small, it could hinder balance.
“I thought, ‘how can I make my leg the right size, and look like it is truly animal-inspired … but at the same time not make it look funny?’” he said. “Then I started sketching.”
Lin’s sketches soon evolved into a series of five 3-D printed prototypes, morphing human aesthetics with mountain goat mechanics.
His final design, the Klippa, has three major features that could give amputee climbers a boost, he said. The first one is size.
“The small contact surface lets you stand on steep ledges, small rocks … and perform different climbing techniques,” he said. “It is about half the size of a human foot.”
The device has a pointed toe that can wedge into tiny cracks, and under pressure, can split like a hoof to grab securely onto rock.
The wide heel is made of firm, replaceable rubber, allowing traction and balance when standing or walking. The final feature, a pivoted ankle joint, is equipped with an internal spring and elastic cord that adds real-time feedback stemming from the sole of the foot, Lin said.
“The cord is attached from the end of the ankle to the main body,” he said. “When pressure is applied to the tip of the foot, the joint pivots. When the pressure is released, the foot bounces back.”
The Klippa’s system could deliver natural control to users, but how many will use it is yet to be seen. Though Lin has completed a final model of the device, it has not been tested or produced by any prosthetic manufacturers.
There is concern that the rubber sole may not be securely attached to the body, and that the elastic pivot cord could get caught or snap during climbing.
But those issues can easily be solved, Lin said. He is working to find practical design solutions for the leg, and is exploring new ways to expand its capabilities.
“It should not be hard to add height adjustment and strengthen the elastic pivot joint,” he said. “I think an above-the-knee [option] could be a possibility as well … but we will need more testing in order to find out.”
That testing will happen soon, Lin said. He recently received a provisional patent for the Klippa, and has been contacted by several manufacturers to begin initial phases.
“I have been working with them, doing a lot of emailing back and forth and trying to see which one works best,” he said. “I would like to design a market-ready version at some point … one that that could fit with already existing prosthetic systems.”
But for now, Lin will focus on the task at hand. He plans to continue improving the device and to develop a working prototype before he graduates in May.
“There are not a lot of prostheses like this on the market,” he said. “I want my device to change that … to augment normal ability.”
The Klippa could do that, he said. He hopes it will change the perception of what amputees are capable of, and give the O&P industry a leg up along the way. — by Shawn M. Carter
Disclosure: Lin has no relevant financial disclosures.