The morning Maria Ramos Gonzalez and her teammates were scheduled to present their mechatronic recumbent bicycle prototype to a panel of Senior Design judges, the system malfunctioned.

“I’m still in touch with four [team members], and we recall that moment quite a bit,” said the now UNLV graduate and distinguished postdoctoral fellow at the Massachusetts Instititue of Technology. “That’s how it goes.”

The team had disassembled the apparatus in the college’s machine shop, wheeled it across campus, and reassembled it in the Thomas & Mack Center for judging during the College of Engineering's capstone event. In the process, a cable snapped.

They had video evidence of the bicycle, which was designed for children with disabilities, in proper working order. But the judging panel preferred a live demo. 

“Maybe if we had had a time slot later in the day…” Ramos Gonzalez mused. 

Perhaps that’s why she’s having flashbacks now. She is the technical advisor for team ExoPush — one of the more than 40 student teams presenting on May 8 during the 25th anniversary of Senior Design. ExoPush is up first with the judging panel. 

But with Ramos Gonzalez's guidance, team members feel well prepared and are not expecting any mistakes.

“It’s nice having someone like Maria, who knows what they’re doing, who understands the field, and understands the processes, to guide you, and also help you catch any mistakes you may not have considered,” said Adi Pahima, a senior mechanical engineering major and member of the ExoPush team. “She’s been a huge resource in helping us get our product made.”

Ramos Gonzalez worked with team ExoPush in the leadup to the competition. Their project — a lower-limb exoskeleton designed to provide both assistive and resistive support for users with varying mobility and strength needs — falls in line with the in biomechatronics and human factors research she’s been doing for the better part of a decade.

Brendan O’Toole, professor of mechanical engineering and faculty advisor to team ExoPush, knew the alumna would be just what the students needed. He has watched her career begin with the questions she learned to ask as an undergrad.

Through the recumbent bicycle project, she and her team interviewed real parents to ask: “What would you like for your child? What would you like to see your children with disabilities achieve with a bicycle that could help them exercise?”

She continued asking these same types of questions working alongside O’Toole for her Ph.D. dissertation, where she developed and tested a novel knee implant design, further exploring the harmony between our bodies and assistive machinery.

“So what does it take, first of all, to design something for a human? How do you make sure it’s safe? How do you make sure it’s accessible?” said Ramos Gonzalez, adding that these are the kinds of questions she guided Team ExoPush to answer.

Programs like UNLV’s Senior Design Competition — a flagship, biannual event for the College of Engineering — are crucial to helping budding engineers “see how their design decisions affect someone in the real world,” she said. 

In particular, the ExoPush team has pushed for designing a low-cost exoskeleton system that can be accessible to a wider range of people and potentially help people in their own lives. 

“Our inspiration came from some of our family members,” Pahima said. “One was my aunt. She suffers from weak knees and has difficulty standing and sitting.”

In assistive mode, ExoPush is designed to support individuals with joint weakness, aid in physical therapy, and help caregivers assist patients with mobility tasks. In resistive mode, it enables strength training by adding controlled resistance and offers applications in fitness, at-home rehabilitation, and even astronaut training in low-gravity environments, said Leanne Steward, another team member, and soon-to-be graduate.

Pahima and Steward are joined on Team ExoPush by fellow mechanical engineering majors, Cade Harris and James Fish.

The dual-function design promotes independence and self-improvement, allowing users to adapt the device to their daily physical condition or goals. 

“The project integrates knowledge from across our engineering education and aims to push the boundaries of wearable robotics in accessibility, functionality, and user-centered design,” said Steward.

Both O’Toole and Ramos Gonzalez believe Team ExoPush’s prototype has viability, and while the system still hasn’t been tested on humans, they could see that being the next step, post-Senior Design, if the team wanted to continue the work.

“I think they’ve done a really good job of delving into the [Institutional Review Board] process and what it would take to run a full experiment on human subjects,” said Ramos Gonzalez.

They’ve also been committed, O’Toole said, to the design and build process throughout the entirety of the Senior Design process, which lasts two semesters for most majors.

Just a few weeks ago, the team began using the Engineering Maker Space, which officially opened this semester, to get the prototype over the finish line.

“With advanced tools, from 3D printers to CNC [Computer Numerical Control] machines, the Engineering Maker Space accelerates design, fosters creativity and collaboration, and equips student teams for real-world innovation across Senior Design and other projects,” said Yingtao Jiang, associate dean for undergraduate programs at the UNLV College of Engineering.

Bringing the design out of the computer and into a real-world lab environment like the Maker Space is a crucial part of the Senior Design process, O’Toole said.

“Things come up in Senior Design that don’t always come up in traditional lecture classes, so it does help with getting students prepared for the workforce,” he said, adding that purchasing the right materials and fabricating parts requires good scheduling and planning up front.

Ramos Gonzalez agreed.

“Maybe you find that you could 3D print something instead of putting it on the CNC machine,” she said. “Can that part still withstand the forces? If yes, that means you’ve just cut your production time a lot and you’ve probably also saved money on the material. As mechanical engineers, we really think about the overall cycle.”

If Team ExoPush was able to produce their product for actual human use, at this point, it would cost about $700 per unit, which is a much more affordable price tag from the $10,000 or more units they found as part of their market research, said Pahima.

They’re planning to demo the device — in lieu of a human participant — on a costume skeleton model Steward borrowed from one of her professors. 

“Getting hands-on experience is really important because you can know all the knowledge, but when you get to the moment, will you forget all of it, will you freeze? Do you remember what you learned, and can you apply it in real life versus can you apply it in a textbook?” Steward said.

Just as Ramos Gonzalez and her team prepared the evening before the competition, team ExoPush is in the final stages of manufacturing the parts and getting the prototype in full working order. 

As far as the prizes up for grabs — first- and second-place discipline specific categories as well as a slate of other prizes for innovation, commercial potential, sustainability and others — those come secondary.

“We more so wanted to work on a product that we would be proud of,” Steward said. “I’m personally not a very competitive person, so, if the money comes, it comes. I just want to be proud of what we did. It’s a meaningful project that meant something to all of us.” 

That’s exactly the mindset of a real engineer, said Ramos Gonzalez, and it reflects the greater purpose behind Senior Design.

“Just based on their design, they could already help somebody. That’s the goal I think, for a lot of engineers that get involved in making products for humans,” she said. “Later on, if they spin out into a company they’ll think about profit. The first phase: let’s help somebody.”