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Mechanical engineering seniors envision improved 3-D printed prosthetics

Thomas Hillman and his team were inspired by his friend’s partial hand amputation to produce a prosthetic prototype without physical limitations. | Courtesy of Thomas Hillman

A motorcycle accident left mechanical engineering senior Thomas Hillman’s best friend with a partial hand amputation. With few durable replacement options available, his career in construction ended.

Thanks to 3-D printing technology, a repurposed Kinect — the motion sensor for Microsoft’s Xbox 360 game console — and guidance from mechanical engineering professor Richard Bannerot, Hillman and his team of mechanical engineering seniors plan to produce a prosthetic prototype without physical limitations.

“It could do things like turn a wrench or swing a hammer,” Hillman said. “But it will also be able to screw in a lightbulb without breaking it.”

Hillman said that, although he started out researching the process of constructing a sturdier prosthetic on his own, he ultimately decided to get help.

Hillman also realized then, he said, that he needed a focus for the capstone project, or the purpose of Bannerot’s course.

The Accreditation Board for Engineering and Technology required that students in accredited engineering programs must complete a capstone experience.

“I saw this as an opportunity to not only get help, but to also enlist some of the brightest students from MECE (mechanical engineering department) that I could find,” Hillman said.

Part of the work he did before proposing the idea to the capstone team, Hillman said, involved making a 3-D scanner out of the Kinect. The repurposed sensor produced the hand that Hillman could then assess.

According to the design proposal, the team aims to produce an affordable and durable prosthetic hand. An added benefit of the 3-D printed design, Hillman said, will be the ability to create custom replacement parts from anywhere.

“Most prosthetics use parts and materials that are delicate and/or expensive to create,” said Lauren Ford, another senior member of the team. “With a more affordable design on the market, it will give people of lower income a chance to have a prosthetic that they won’t have to spend their life savings on.”

Per the design report, a person seeking a functional prosthetic hand would pay between $30,000 and $50,000; for this price, they would still most likely end up with a brittle and weak prosthetic with parts that are difficult to replace.

The prosthetic that the team has designed, based on the report, will match the strength and movement of a human hand. Combined with the ease of part replacement, users of the hand can continue to work in an industrial setting.

“The prosthetic project is one of the most ambitious ME capstone projects undertaken by a single team,” Bannerot said. “The prosthetic project is a great project because it combines many engineering disciplines — mechanics, strength, materials, controls, electronics, human factors, etc. — and, of course, has a humanitarian goal.”

While the team has focused mostly on brainstorming and design this semester, Hillman said they plan to build the prosthetic in the spring.

“Think of the muscles that control your actual fingers. Each joint needs a combination of muscle fibers to contract or relax so that the finger can move,” Ford said. “That is the basis of our movement.”

The team, Ford said, hopes that the creation will be more than just an assignment. He also added that, from the team’s perspective, the project’s setup lets new teams rebuild and improve the design each year.

“(Hillman) found a doctoral research team that is working on creating/refining a method to control a prosthetic with brainwaves,” Ford said. “We would love for them to eventually be able to use our prosthetic to help their research.”

Hillman said that he would like to merge the efforts of the two teams one day.

Although the doctoral team is still in the early stages of their project, Hillman said that a future combination of their work could let the brain control the prosthetic via electroencephalograph, or EEG.

“I know I will not stop working on this. My friend still needs a working finger,” Hillman said. “This has been a great opportunity to push my limits and try something incredible.”

To build and test the prototype, the capstone team will accept funding donations throughout Spring 2017.

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