High Schooler Invents Affordable, Mind-Controlled Prosthetic Arm

When the COVID-19 pandemic first hit, some of us were lucky enough to find ourselves with ample free time to develop a skill or work on a passion project. For some, that meant learning how to bake bread; for 17-year-old Benjamin Choi, it meant developing a prosthetic arm that can be controlled by the user’s mind. 

Choi has always been fascinated with the concept of thought-controlled prosthetics, having first seen one on an episode of “60 Minutes,” according to Smithsonian Magazine. But he didn’t like how inaccessible these prosthetics were as they required brain implants (and therefore risky surgery) to work. So when the pandemic slammed the brakes on what would have been Choi’s summer research project, he set about creating a cheaper and safer solution.

He used prior engineering and coding experience (garnered from school and Stack Overflow) to design a durable prosthetic arm, as well as an AI algorithm capable of translating the user’s brain waves into commands. The system is accompanied by a relatively small headset, which uses electroencephalography (EEG) to read the user’s brainwaves. The headset sends these readings via Bluetooth to a microchip embedded in the prosthetic, where Choi’s algorithm deciphers the brainwaves and turns them into movement. The final product costs just $300 to make.

As easy as Choi makes this look, his journey to developing a working prototype wasn’t easy. He initially wanted to store his algorithm in the cloud and run communications via Wi-Fi. This wasn’t practical though, since the user would have to remain connected to Wi-Fi and the prosthetic’s movements would be significantly delayed. He also created more than 75 versions of the prosthetic before settling on its final design. 

Today, Choi’s algorithm consists of “over 23,000 lines of code, with 978 pages of math and seven completely new sub-algorithms.” Its average level of accuracy is 95 percent, which far surpasses the industry’s standard, which Choi says hovers around 73 percent. 

Since his invention caught widespread attention last year, the now-high school graduate has won multiple awards. He’s also earned a fellowship at Stony Brook University, and acquired a grant to produce his prosthetic. Choi has even obtained provisional patents both for the prosthetic and his algorithm, though he’s published instructions for anyone who’d like to 3D print a prosthetic arm of their own. 

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