It seems the stuff of science fiction, but Potomac School senior Ben Choi has designed a prosthetic arm that can be manipulated using the wearer’s brainwaves.
Choi’s invention has earned him a guaranteed $25,000 prize and top-40 finalist spot in the Regeneron Science Talent Search 2022 contest, which will wrap up in March in Washington.
Student inventors from around the country will compete in the weeklong finals for a $250,000 grand prize and more than $1.8 million to be awarded overall. Top scientists from around the U.S. will interview the contestants and judge their projects.
Choi, the son of attorney Erin Cho and cardiologist Brian Choi, was born in New York City and has lived in Northern Virginia since age 4. He has attended Potomac School since the first grade and takes part in the school’s selective Science and Engineering Research Center program, where he does high-level independent-research projects.
A 2012 “60 Minutes” documentary about mind-controlled robotic limbs inspired Choi in fall 2020 to create his prosthetic arm. His dubbed his project (take a deep breath) “An Ultra-Low Cost, Mind-Controlled Transhumeral Prosthesis Operated via a Novel Artificial Intelligence-Driven Brainwave Interpretation Algorithm.”
Designing a 3D model of the arm took about eight months and posed many challenges, Choi said. He maximized the prosthetic’s capabilities by optimizing every detail at a millimeter-level of precision, which required him to design channels, complicated lattices and systems driven by artificial tendons.
The 2.5-pound appendage is about the size of an adult human arm and is relatively light for an upper-limb prosthesis. The arm’s motors and microchips need only 5 volts of energy and can be run from a variety of power sources, Choi said. A typical real-world user would power the arm via an external battery, he said.
Choi assembled the arm using 20 3D-printed pieces. Those components take a few hours to produce, depending on the printer’s bed size and manufacturing capabilities, he said. The arm also contains dozens of mechanical and electronic components, he added.
PolySpectra Inc. helped Choi with a manufacturing grant that allowed him to use the company’s industrial-grade digital-light-processing 3D printers and ultra-durable COR Alpha filament to produce the final version of the arm.
Guiding the arm via its user’s brain signals proved difficult.
“Brainwave data, especially residual data read non-invasively via scalp electrodes, can be super-fuzzy and sparse, so building an [artificial-intelligence] model robust enough to decode those signals in real-time was a major obstacle,” Choi said.
The arm is controlled via a dry, single-channel, brainwave-detecting headband made by Neurosky.
“I chose this headset over conventional EEG [electroencephalogram] setups as it is compact, easy to don and cost-effective,” Choi said.
Choi via trial and error has been able to make the arm’s movements about 95 percent compared with a human arm, Potomac School officials said.
Clinical trials with amputees, which the arm is undergoing, will determine its full capabilities, but results so far show the arm can perform many object-manipulation and transfer tasks, Choi said. The arm can handle a various objects of different sizes and weights.
“Its mechanical components are pretty heavy-duty and high-strength,” he said.
Choi conducted an Institutional Review Board-approved human study that collected brainwave data from a wide variety of people who performed neuroprosthesis-control tasks, such as thinking about clenching a fist. Choi used the study data to test his prototype’s control system and received feedback from an upper-limb amputee who contacted him after hearing the project.
“I’d love to see this prosthetic-arm project through all the way to real-world deployment,” he said. “I don’t have any set future plans in mind in terms of future projects, but I definitely want to continue pursuing STEM/engineering research and creating things to help people.”
Throughout the development process, Choi has been mentored by Isabelle Cohen, an upper-school science teacher at Potomac School, and Ji Liu, an assistant professor of electrical and computer engineering at Stony Brook University in New York.
Choi is an “incredible young man who has shown creativity throughout the entire research process,” said Cohen, who added she only made occasional suggestions for the project.
“What has been most amazing throughout the last two years working with Ben has been his ability to merge different fields of science and to connect with researchers, engineers and entrepreneurs alike in order to verify his understanding and refine his experimental approach,” she said.
Choi’s prosthetic arm is durable and lightweight, does not require the user to undergo brain surgery and costs less than $300 to produce, all the while obtaining performance comparable to the most advanced mind-controlled limbs currently existing, Liu said.
Liu, who also was Choi’s research mentor when he was a 2021 Simons Fellow in the Simons Summer Research Program, said the student’s prosthetic-arm project showed an “extremely high level of intellectual curiosity, critical thinking and self-motivation.”
“His project is not only a creative high-school research project for related patients, but also may have a big impact on our society with the increasing aging population,” Liu said.
Successful clinical trials will allow Choi’s prosthetic arm to advance toward real-world deployment. Choi has filed provisional patents for the prosthesis itself and its artificial-intelligence-driven neural-control system.
“Corporate acquisition, especially of the brainwave interpretation algorithm, is definitely a possibility,” he said.
By being chosen a finalist in the competition, Choi is in good company. According to Potomac School officials, contest alumni include winners of 13 Nobel Prizes, 11 National Medals of Science, six Breakthrough Prizes, 22 MacArthur Foundation Fellowships and two Fields Medals.
Choi is thinking of studying engineering in the future, but has not selected a college yet.
“I’ve also got a pretty wide range of interests and really enjoy the humanities, so I wouldn’t want to give that up in college, either,” he said.