3D printing brings affordable prosthetic “Victoria Hand” to Guatemalans

University of Victoria Professor, Nikolai Dechev, with students Michael Peirone and Joshua Coutts, are combining MEMS sensors with 3D printing to produce low-cost body-powered prosthetics For an individual who has lost their hand to injury or disease, choices for prostheses are limited to either devices with a simple pincer grip, or a $70,000 state-of-the-art “bionic” limb.

In low-income nations, the absence of affordable prosthetic solutions leaves many with no option at all. And even in Canada, the want of a realistic-looking, high-function, low-cost prosthesis motivates some amputees, especially image-conscious youngsters, to go without. 

Fifteen years ago, that lack of choice spurred Nikolai Dechev, a University of Toronto graduate student in mechanical engineering, to create an all-mechanical, five-fingered prosthesis suitable for young people. It combined both advanced function and realistic looks. 

His approach was driven by two considerations: “The younger you engage a person to wear a prosthetic, the more likely they are to adapt one into their lifestyle,” he says. As well, a hand design sized for children has broader applicability, because it can be scaled up in size. Artificial hands don’t scale down as well as they scale up—if shrunk, the components nonlinearly decrease in strength.

Using his novel concept of “adaptive grasp,” he produced a prototype with semi-independently moving fingers and thumb, capable of flexing and forming themselves around the shape of the object they are grasping. But at a manufacturing cost of about $15,000 per unit, scale-up to mass production wasn’t feasible, and the technology was shelved.

That experience, however, combined with the emergence in the late 1990s of micro-electro-mechanical systems (MEMS), sharpened his research focus. “The prosthesis project showed me the great need for implantable sensors,” he says. “Such sensors are needed to extract bio-signals from the body, which can be used to control advanced prosthesis.”

His subsequent PhD and postdoctoral work explored the design, development and robotic assembly of 3D MEMS devices. Today, the Associate Professor of Mechanical Engineering at University of Victoria is breaking new ground in the development of novel sensor technologies enabling better control of prostheses. This work includes ultrasound-based sensing of tendon displacement in the wrist, and implantable wireless sensors to measure the electrical activity of muscles, and to stimulate tissues.

About two years ago, thanks to rapid advances in high-quality, low-cost 3D printers, Professor Dechev started thinking about 3D printing prosthetic hands. Together with his research team at the Biomedical Design and Systems Laboratory, they are now transforming his graduate-school prosthetics project into a body-powered cable-driven, locally manufactured hand prosthesis for amputees in Guatemala, at a projected cost of about $200 each.

“I always wanted to deploy the hand for amputees,” he says. “I knew the design was robust, and because it is all mechanical, it lends itself to transfer from machining manufacturing to the new world of 3D printing.”

The group used Solidworks, made available through CMC Microsystems, to redesign the components. “This was absolutely essential to use,” Prof. Dechev says. “Having that access to low-cost software definitely enabled this project. We’d really be struggling without it.” COMSOL, another CMC-licensed tool, allowed them to simulate the hand for strength testing.

"We wanted to develop a well-engineered, 3D printed version of the prosthesis, and to test it with amputees and receive their feedback,” says Prof. Dechev. So he and his team applied to, and were awarded, $112,000 from Grand Challenges Canada, a federally funded organization with a mission to support global health for low-to-middle income countries.

Prof. Dechev and his team are now working with Range of Motion Project (ROMP), a non-governmental agency providing prosthesis care in Guatemala. Together they will deploy the Victoria Hand, as they have named it, with a small number of experienced artificial hand users in Guatemala, in a Canadian-approved clinical trial.

A key funding requirement is to ensure sustainability of the project by transferring their know-how to the local community. This means not only training clinic staff to operate a 3D printer, but also providing workable design kits. “This is really important,” Prof. Dechev says. “It’s about providing the materials and documentation such that anyone technically inclined could reproduce this in any developing country. It’s also about communicating the idea. It is a wonderful training experience for my students.”

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