Mechanical engineering graduate student Gwyn O’Sullivan, student in the HGN Lab for Bionic Engineering, is a recipient of the National Science Foundation’s Graduate Research Fellowship Program (NSF GRFP). This prestigious fellowship supports outstanding doctoral and research-based master’s students doing research in science, technology, engineering and mathematics, or STEM disciplines.
Established in 1952, the NSF GRFP is the oldest fellowship program of its kind. The 2025 fellows receive a three-year annual stipend of $37,000, a $16,000 cost of allowance for tuition and other costs, and numerous research and professional development opportunities.
O’Sullivan’s research is focused on developing a ‘semi-active’ prosthetic ankle. Most current prosthetics are ‘passive’, meaning that they act as simple springs that store energy as an amputee puts weight on it, then releases the energy as they push off the ground and walk. They are optimized for walking on level ground, making them inefficient for other activities.
“Some powered prosthetic ankles have been developed,” said O’Sullivan, “however, they tend to be heavier, noisier, and more expensive than their passive counterparts. The semi-active ankle would bridge the gap between these. It will store and return energy like a passive ankle while walking but will have a small motor that adjusts spring stiffness. This will allow it to adapt to different activities and provide the adaptability of a powered device while being much lighter and cheaper.”
O’Sullivan’s interest in prosthetics isn’t new. She grew up watching sci-fi movies and TV shows with her dad that were full of high-tech medical devices. As she got older, she was drawn to advanced biotechnology and prosthetics in specific.
“I loved the idea of people having the option to receive a new limb that worked just as well as their old one,” said O’Sullivan. “Once I realized that prosthetics weren’t as advanced in the real world, I started following developments in the field. That led to an opportunity to work in prosthetics-based research in my undergrad, where I discovered I enjoy working with people as much as the devices themselves. From there, I came to the U to continue my prosthetics research.”
Working in the HGN Lab will give O’Sullivan the opportunity to work in research and development while also learning more about academia. She has always wanted to be involved in prosthesis design and this project will give her the opportunity to really sink her teeth into every stage of the process.
“My favorite part of the design is eventually getting to hold the device that was, once, just an idea,” said O’Sullivan. “I can’t wait to have that moment with my prosthetic ankle. That moment is the ‘carrot on a stick’ that drives me. And while I’ve never made a prosthetic ankle before – my literal dream – my research doesn’t end there. I’ll be able to have an amputee actually walk on a foot I designed. Just thinking about it blows my mind.”