Hailey Dawson calls it her "special hand." And it is indeed different. The 4-year-old's right hand has a pinky, a thumb, and three "nubbins," as her family members refer to them, in place of the other fingers. Hailey has Poland Syndrome and was born without a right pectoral muscle, which also affects the growth of her right hand. But, as children do, Hailey has adapted well and she seems convinced there is nothing in the world she can't do.

"She'll even tell some people, 'You can't do that because you don't have a special hand,'" her mother, Yong Dawson, said with a laugh.

But there are some barriers Dawson would like her daughter to overcome. Holding a bike's handlebar, for example, is difficult, and Hailey wants to play baseball.

At a cost of $20,000 or more, traditional prosthetics are not feasible for a growing girl. Dawson turned to the Internet and came across Robohand, a South African organization that is using 3-D printing technology, along with various wires, nuts, bolts, and hinges, to create cost-effective prosthetic hands. The concept is open-source; anyone can access the 100 or so Robohand files and use them to create their own prosthetics, so long as the models aren't being sold for a profit.

Dawson considered working with the organization to create a hand for Hailey, but the process would require shipping prosthetic pieces back and forth for constant re-sizing and fitting. So the Henderson mother emailed UNLV's Howard R. Hughes College of Engineering to see if anyone there could help and was surprised by the response.

"I walked in thinking I was going to sell them on what I wanted done. But it was the complete opposite. They were trying to sell me on letting them do it," Dawson added.

An opportunity, a bond

Brendan O'Toole, chair of the mechanical engineering department, and Mohamed Trabia, associate dean for research, graduate studies, and computing, took on the project. O'Toole has worked with foot and ankle prosthetics, but those projects did not involve 3-D printing.

"We liked the idea of a community-based design where we're using our research and resources to help someone," O'Toole said. "That, coupled with 3-D printing improvements in the last couple of years, made for some pretty good design opportunities. So it also makes a good learning project for engineering."

Trabia and O'Toole started in May. They were joined by Katherine Lau, a visiting student researcher from Rutgers University; UNLV engineering student Zack Cook; and Advanced Technologies High School students Claire Ong and Kareem Trabia (Mohamed Trabia's son).

Lau, a Palo Verde High School graduate, was home for the summer and looking for a research project. She found that, as well as an important personal connection with the Dawson family.

Lau shared a common bond with Hailey and her family of being from Hawaii. The cultural connection with the shy preschooler proved helpful during the many time-consuming fittings and measurements Hailey underwent throughout the summer. Hailey had to sit still for long periods while the molds of her hand set. And there were plenty of other long waits as the team tinkered with ways to make the hand look and feel more natural.

"The whole reason I went into biomedical engineering was to improve the lives of others," Lau said. "I didn't want to make something and give it to someone and never meet them. Getting to know her made it more personal; it helped me to do a better job. The first hand didn't really fit because I didn't take the time to get to know her. It was just measurements and a picture. I didn't want to make that mistake again."

The journey

Initially, the researchers thought that one of the Robohand concepts, among the roughly 100 or so already developed and available to the public, would be a perfect fit for Hailey. But none were, and the team needed to start from scratch, creating a customized hand blending design ideas and materials found around the world through Internet research.

The new hand will bend and grip with the flex of Hailey's wrist. To improve grip, the team tweaked their design with ideas from the Flexy-Hand platform. "The tasks the person using the hand wants to accomplish affect the design," said O'Toole. "One challenge is that once you get to use the hand, does the amount of wrist flexation give enough grip to do with it what she wants to do?" Like swinging a bat.

UNLV's Stratasys Fortus 250MC 3-D printer has been the workhorse for this project. The machine's very fine resolution allows for precision printing of parts. In the machine, a yarn-like spool of plastic filament connects to a print head, which sprays layers of plastic just 0.007-inches thick until eventually smooth, very real-
looking hand shapes form. The team chose ABS (acrylonitrile butadiene styrene) plastic for all-weather use.

"It's not going to be completely smooth, but it does get pretty close," said Jeff Markle, director of the mechanical engineering department's laboratory.

The more intricate the project, the longer and harder the Fortus must work, adds Markle. Some print jobs can take several days, and several versions of Hailey Dawson's prosthetic hand, and its numerous small pieces, have had to make their way through the Fortus machine. The greatest challenge still lies in translating the idea from the CAD software into a final 3-D product.

"As with anything, when you have the model in the computer it looks good. But when you really assemble it, that's when you see the problems," Trabia said.

The team enlisted local occupational therapists from Touro University and from Matt Smith Physical Therapy to fine-tune the fit and help Hailey adjust to the hand.

Next steps

As UNLV works to open a medical school in 2017 and enhance community-engaged research as part of its Tier One initiative, both Trabia and O'Toole hope UNLV will land grants to further the study of prosthetics. The pair notes that prosthetic advancements are largely tied to the trial-and-error of hobbyists rather than the intensive research of academics. "Most of the information you find is more amateur kind of people tinkering and creating variations on models," Trabia added.

O'Toole said expanding research in this area will build on the expertise already on campus. The next logical step is partnering with kinesiology, physical therapy, and occupational therapy experts to help the hand feel more natural and comfortable for Hailey. And, since she'll need replacements periodically as she grows, Hailey's special hand might continue to be perfect for student projects. All engineering students must complete a capstone project before graduation.

"We see possibilities for improving all forms of mechanization, things like actuators to make each finger close and open independently," Trabia added.

In the meantime, Cook has taken over as the lead student researcher. The group expects Hailey to be swinging a bat with her new hand later this fall.

"What they've done so far has been amazing," Hailey's mother added.