Mechanical engineering graduate students Karen Walker and Gwyn O’Sullivan, both students in the HGN Lab for Bionic Engineering, are recipients 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.
This fellowship highlights the impressive work these two students are doing. Walker is doing in investigating the impact of prosthetic devices on the biomechanics and mobility of individuals with lower-limb amputations. O’Sullivan’s research is focused on developing a ‘semi-active’ prosthetic ankle.
Walker had the opportunity to volunteer at a prosthetics and orthotics clinic during her undergraduate studies and saw firsthand how resilient people with mobility impairments can be. She also witnessed the powerful role that assistive devices can play in restoring independence and changing someone’s life, which motivated her to pursue research that helps others stay mobile and healthy.
“What excites me most about this research is the potential to make a real difference in the lives of people with amputations,” said Walker. “The work I’m doing could play a pivotal role in shifting the way we approach mobility for amputees, by showcasing the benefits of powered assistive devices. This is a step toward creating prosthetic devices that are not only functional but truly enable independence and enhance quality of life. It feels like we’re on the cutting edge of something that can have a big impact.”
Walker plans to continue doing research that supports individuals with mobility impairments. Her goal is to help optimize devices that enhance mobility so users can walk more naturally, efficiently, and pain-free. This research will contribute to innovations that make assistive devices feel like a true extension of the body, bridging the gap between function and freedom, to play a role in expanding what’s possible in assistive technology.
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. Working in the HGN Lab will give O’Sullivan the opportunity to work in research and development while also learning more about academia.
“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 semiactive 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.”
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 O’Sullivan working on a design 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.”