An Amputee Acquires a Prosthetic Finger From an NJIT Capstone Team
After a table saw severed the top of his right index finger, Adam Zanellato, a 20-year-old cabinet-maker at the time, had to relearn basic hand maneuvers, such as how to write and hold a fork. There were no affordable prosthetics on the market to help him regain dexterity. Several years later, he still found it hard to pick up coins from a table.
A year and a half ago, he decided to restart his search, and began by contacting a friend in medical school for leads. The woman, an NJIT graduate, made this recommendation: present himself as a research project to students in the university’s biomedical engineering department, which has a strong focus on rehabilitation. She contacted Sergei Adamovich, the director of NJIT’s Center for Rehabilitation Robotics, who agreed to supervise a team with the help of Ashley Mont, a third-year Ph.D. student who specializes in robotic exoskeletons.
A team of four – Ricardo Garcia, Ashe Pignataro, Madison Taylor and Giovanna Nolan – quickly agreed to make it their senior capstone project and promised Zanellato that they would build him a prosthetic finger.
“With our specialized technologies and printing capabilities, the possibilities for design and customization are endless,” Mont notes, adding, “I had worked with each of these students and knew that if any team of undergraduates could succeed, they could.”
“This was not a theoretical exercise. We wanted to make sure our prosthetic was functional – that Adam was able to grip with strength and dexterity, hold utensils and even some tools, while also being able to lift small objects,” says Garcia, the project leader, adding that the team submitted their project for review by the university’s Institutional Review Board to develop a legal framework for where and how the device could be used. Four visits to campus and 10 prototypes later, he now wears it at home for simple tasks (below).
Their finger, which features an artificial interphalangeal (hinge) joint system, uses the force generated by the remaining part of the finger to power it, thus mimicking normal finger flexion and extension. To make it affordable, they developed a method for manufacturing it with a 3D printer, using strong but inexpensive materials.
“In terms of design, a key challenge was making sure that it could be easily reproduced if damaged by simply reprinting a part,” Taylor notes.
“Our goal was to make it look more and more like a finger without sacrificing the mechanics,” Nolan says. Pignataro adds, “Every tweak to the geometry has a story behind it. When it was pinching, we added a curve.”
Their invention won first prize in the university’s undergraduate TechQuest Challenge on Innovation Day last year. It has since acquired a name – The DeXter – and a professional description: “a body-powered finger prosthetic for subjects with amputations distal to the proximal interphalangeal joint.” The team recently filed a patent on their invention through NJIT and is seeking to commercialize it.
“It’s very unusual that students have the chance to design a prosthetic for a specific person,” Adamovich says, “but that’s what made this project so exciting.”