Reimagining mobility: Tulane students design low-cost device for foot drop

In a biomedical engineering capstone course at Tulane, a group of students confronted a condition that can turn something as simple as walking across a room into a challenge: foot drop.

Foot drop is the inability to lift one's foot properly. When someone who has the condition lifts their leg, the foot simply hangs down and points toward the ground, making walking difficult and unpredictable. The condition is often a symptom of neurological disorders such as stroke or multiple sclerosis.

The Tulane students designed a device that allows the foot to respond in real time with the rest of the leg. Their device combines sensors, small onboard computers and mechanical components that work together to lift the foot at the right moment in each step.

The design uses an accelerometer and gyroscope that determine the angle of the person's thigh as they are walking. The accelerometer and gyroscope then tell linear actuators attached to the foot whether to extend or retract, explained Matthew Scherp, who, like the other members of the student team, is majoring in biomedical engineering at the School of Science and Engineering.

Most existing solutions for foot drop rely on rigid braces that hold the foot in a fixed position. While those devices can prevent tripping, they often come with tradeoffs in comfort, cost and long-term recovery.

"This is $600," student Marisa Ricci said, referring to a commonly used brace that locks the foot into place. "And it's not really very comfortable, and it also doesn't help you recover."

The Tulane team sought out affordable components for their system.

"Our linear actuators are like $20. We just bought hobby components," Ricci said.

Each device costs about $100 to make, Scherp said.

The team's success began by working with real people with foot drop.

"We've been plotting on it for a while," said Allison Wu, another member of the team. "Marisa has a family friend who has foot drop and has been struggling to find a device. After interviewing him, we felt like that was a good fit."

Then, the team visited a rehabilitation clinic and began working with stroke patients.

"We got the opportunity to come and hang out and learn a bit more about what it really looks like for people that have foot drop," said student Matthew Vuong.

For the students, the project brought together everything they have learned over four years at Tulane, from circuits and coding to mechanical design and patient-centered thinking.

"It's seeing all the things we've learned over the past four years come together," said Ricci. "The marrying of the electrical and the mechanical side." The project also pushed students beyond traditional engineering. Through the process, they explored commercialization, patent development and the broader question of how an idea becomes a real product.

"The class also gives you a lot of exposure to other facets of biotech," Wu said. "We talk about commercialization, entrepreneurship … and I've gotten to practice writing a patent."

The project is still in development, with testing and approvals ahead, but the team is eager to share what they have built.

The students hope their work continues beyond this semester. "We hope to pass down the project," Wu said. "I think it could be a good project to continue for future classes."