How Two College Students Created A Prosthetic Arm For An 8-Year-Old

Daniel Wilson wanted a prosthetic to let him ride a bike and swing a bat (and he wanted it to be red), so two engineering students found an ingenious way to make one for him.

Meet Pinchy, a prosthetic arm with two hooks that can–as its name might indicate–pinch things. Pinchy belongs to Daniel Wilson, an 8-year-old from Rockville, Indiana, who was born with a shortened arm that has two fingers on the end. Daniel’s family didn’t have to go through a high-tech prosthetic company to get Pinchy–the device was custom-made by two college students at the Rose-Hulman Institute of Technology.


Every year, Rose-Hulman seniors work on capstone design projects. After reading about some former students who created a prosthetic arm for a local Indiana boy, Daniel’s family got in touch with the school to see if they could do the same for Daniel. Lo and behold, Daniel’s prosthetic made it onto last year’s list of potential projects. Biomedical engineering students Mark Calhoun and Jacob Price picked it up.

“Mark and I thought this would be a fun one to work on,” says Price. “Our intro to Daniel was two sentences that said he had a condition which resulted in him having a shortened limb with two fingers at the end and that he liked to play guitar.”

And with that, Calhoun and Price got to work, aided by Siemens computer-aided design and engineering software (Siemens works with 11,000 schools around the world). First, they met with Daniel, who outlined some of his requirements: The prosthetic had to be red and help him do things he struggled with, like picking up a cup, riding a bike, and swinging a bat.

The students spent the first 10 to 12 weeks of school designing the prosthetic, playing around with the Solid Edge software, and coming up with ideas. “We had the most difficulties with the electrical system. There was a a lot of debugging and poking myself in the finger with a hot soldering iron,” says Price, laughing.

Throughout the whole process, they had a Siemens camera crew following them around (check out the video below for the final results). “They got the excitement of coming and living on campus. They lived in the dorms with students,” says Bill Boswell, senior director of partner strategy at Siemens.

In the end, the students came up with a prosthetic that fit Daniel’s requirements. The plastic device is controlled by sliders (similar to audio mixer controls) that control the hand, elbow, and wrist. Daniel can use them without involving his other arm.


Calhoun and Price have both graduated. Calhoun is now in graduate school at Ohio State University, and Price is in Indiana doing validation work for companies throughout the Midwest. They have both been in touch with Daniel and his family–and reportedly, Daniel is still happily wearing Pinchy.

About the author

Ariel Schwartz is a Senior Editor at Co.Exist. She has contributed to SF Weekly, Popular Science, Inhabitat, Greenbiz, NBC Bay Area, GOOD Magazine and more.