Five-year-old Max Ng was a perfectly healthy boy until, at the age of two, he contracted a rare virus called acute flaccid myelitis. Similar to polio, the virus attacked the nerves in his spinal cord, leaving his arms limp at his sides. Max hasn’t been able to lift or lower his arms on his own to use his fully-functioning hands for the three years since.
 
Now, thanks to a lightweight motorized exoskeleton built by four UC San Diego undergraduate engineering students, Max is moving his arms to feed himself, play with his parents, and even enjoy one of the true joys of childhood—picking his nose.
 
“It’s been a heartbreaking journey for him, to watch a kid go from a healthy little boy running around and now to deal with all this,” said Ted Ng, Max’s dad.
 
UC San Diego mechanical engineering students Jose Manuel Rodriguez, Ethan Jen, Cory Wolf and Marcos Serrano-Herrera spent 10 weeks creating a solution for Max for their senior design project. The project was suggested and sponsored by Dr. Andrew Skalsky, division chief of Rehabilitation Medicine, Rady Children’s Hospital San Diego. Skalsky treated Max when he first arrived as a patient three years ago, and has been working on rehabilitation with him since then.
 
“In Max’s situation, the shoulders and elbows were very involved and devastated but his wrists and hands remained almost normal,” Skalsky said. “So we knew that if we could do something to help his elbows move, it would allow him to regain a lot of function he has in his hands without them stuck at his side. We knew this was something that was going to be possible, it was just going to take a unique team to be able to do it.”
 
Skalsky found that team in a group of undergraduates at the Jacobs School of Engineering’s mechanical and aerospace engineering department. Over the course of ten weeks, a team of four mechanical engineering seniors created a working prototype. They met with Max and Skalsky on a weekly basis to get real-life feedback on their latest iterations.
 
After trying several different designs, the team settled on a strategy to allow Max to raise and lower his arms simply by flexing his wrists.  To do this, soft cuffs hold Max’s arms. These cuffs are each attached to a harness around his torso to keep the weight off his arms. Each cuff has an actuator connected to a joint mechanism, allowing the system to curl up and down as an elbow would. The actuator is triggered by sensor gloves, so when Max flexes his wrists up his arms will move up, and when he flexes down, they’ll move down. The system can only move between 30 and 180 degrees, to prevent his arms from overextending. It’s controlled by an Arduino and powered by a battery, which are held in a small backpack-like pouch on his back.  
 
The students said they learned a lot in the process, about electronics, human-centered design, the importance of iterating, and the luxury of time.
 
“To see him walking around without being attached to a circuit board on a table, that was really nice,” said Jen of their first time watching Max use the finished prototype. “Look at all that functionality he has now. It’s a bit hard to describe though, because we’re happy we were able to get him this far, but we feel like there’s more we could have done, too.”
 
Rodriguez said working on the project was one of the highlights of his college experience, in part because of the visible difference they made in someone’s life.
 
“It really didn’t hit me until we were talking to the prosthetist who said ‘You’re making a really big impact in this child’s life.’ When we tested the device out last week we had him pick up a Chewy bar, one of those Quaker Oats bars—he was eating and it felt really good seeing him do that.
 
“I feel like it’s really interesting the way engineering is basically the medium between science and society. You’re that medium, trying to make science practical in a way that impacts society and real life.”
 
These students have certainly impacted the real life of Max. Wearing his new exoskeletal brace, he’s able to throw play punches, hug his parents, and just be a kid.
 
“I think the first time he used it he just picked his nose with it,” Ted Ng said.
 
The students designed the orthotic in conjunction with ABI Prosthetics and Orthotics to be easily modified to grow with Max so the device will serve its purpose long after he outgrows this first version.
 
This team of students was one of nearly 100 teams this year that spent 10 weeks creating solutions to real world problems put forth by members of the community and local companies. It’s part of the capstone senior design course that all mechanical and aerospace engineering students take. The goal is to provide students an opportunity to put all they’ve learned into practice, working within real world constraints like budgets and timelines. Other senior design teams tackled challenges like a self-cleaning 3D printer, a portable gynecological exam table for use in rural India, and a chamber to study coral in the ocean for long periods of time.
 
Rodriguez, Jen, Wolf and Serrano-Herrera said they’re glad they chose this project.
 
 “Part of the reason I was looking forward to doing this project is the benefit of seeing Max be able to use it,” said Jen. “The value added is that you get to see him happy, and it’s a lot more fun than doing stress calculations or something. This project has a name. It’s alive. It’s Max.”