Robotic knees earn amputee inventor fame

Sun Xiaojun, an amputee who made himself a robotic knee, is now working to ensure that his invention is accessible to other people with disabilities to improve the quality of their lives. [Photo/China Daily]

Company seeks funding to make cost of devices more accessible

Sun Xiaojun, an amputee who made himself a robotic knee, is now working to ensure that his invention is accessible to other people with disabilities to improve the quality of their lives.

Born in Shiqian county in Southwest China's Guizhou province, Sun was the naughtiest student in his class until he broke an ankle and was diagnosed with osteomyelitis, an inflammation of the bone, when he was 9.

His right leg was later amputated as a result of the condition.

"It was really unfortunate for me and my family. I was naughty and disliked studying before the amputation. But my father told me that I could only make a living by studying because I was not able to farm like him," the 34-year-old said in a recent interview with Yishou, an online video platform.

Even though his family wasn't able to afford to buy him a prosthetic replacement, the young boy refused to surrender to his fate and made up his mind to study hard.

In 2006, Sun enrolled at the Huazhong University of Science and Technology in Wuhan, Hubei province, to major in material forming and control engineering.

He made headlines when he registered at the university walking with a crutch. In 2009, he won the opportunity to continue his studies at Japan's Tohoku University.

"I started to wear a prosthesis two years after I began studying in Japan. I had never worn one before, so it took quite a long time to get used to it," he said.

The experience wasn't very comfortable because the knee didn't bend, and it took Sun time to go up and down stairs. He would sometimes fall over when he tried to walk too fast, which made him feel awkward. He came up with the idea for a smarter prosthesis by applying robot intelligence in 2013 while he was studying for his master's at the University of Tokyo.

He got a job at Sony after graduating, but he gave it up to pursue a doctorate focusing on humanoid robot research at the university in 2015. He founded BionicM in Shenzhen, Guangdong province, in 2018, so that his inventions could help more people with disabilities enjoy life.

Sun's robotic prosthetic knee quickly earned him fame and won him the Red Dot Best of the Best award in 2020.

He said that the biggest challenge in creating the robotic knee was how to coordinate between the body and the prosthetic. "Walking is an unconscious movement. It's difficult to make prosthetics understand how that works."

Most artificial limbs on the market are made to work like bones and ankles. Sun's invention works a bit like adding muscle to the mechanical parts.

"The prosthesis we've created has a kind of mind of its own, and allows people to move by sensing their intentions," he said.

"I myself use a prosthetic limb, and I'm also a researcher. There are about 4 million people in China whose lower limbs have been amputated," he added. "The cost of an ordinary prosthesis is around 60,000 to 100,000 yuan ($9,400 to $15,700), which many people can't afford, so they use crutches, instead."

Sun said the market is a niche, and most prosthetics are produced in Europe. "I didn't start my company for the money, but to make a product that is useful to society. Amputees have a basic need to walk on two legs," he said.

Sun said that the robotic knee his company produces is priced at around 300,000 yuan per pair, while similar products sold elsewhere average around 800,000 yuan.

Admitting that this is not ideal, he said that his robotic knees are still in small-scale production, resulting in high costs. He hopes that by raising more capital, he'll be able to expand production and lower costs to make his devices more widely affordable.

Zhang Chi contributed to this story.