South Africa’s 3D Printed Mechanical ‘Tenim Hand’ Allows for Individual Finger Control

Let’s be real: I love 3D printed fun things as much as the next person–I have two 3D printed dragons on my desk as I write–but the best part of my workday here at 3DPrint.com is reading and writing about the ways this incredible technology is being used to help people the world over. Medical advances using 3D technology are making huge strides forward, and it’s no exaggeration to say the tech is truly taking the world by storm.

We may be most familiar, when it comes to 3D printed prostheses, with organizations like e-NABLE here in the US, but similar contributions toward reliable, realistically shaped, functional prosthetic devices are being designed and produced the world over. I’m in Cleveland, Ohio; one of the farthest places in the world from me is Cape Town, South Africa (noted especially since I couldn’t attend my sister’s wedding there six months ago–it’s far). And that is exactly where another impressive design for a 3D printed prosthetic hand has been patented.

A duo from the University of Cape Town (UCT), working in conjunction with the Centre for Rapid Prototyping and Manufacturing at the Central University of Technology (CUT) in Bloemfontein, has made waves lately through the development of a mechanically operated prosthetic that has already proven to be award-winning and impressively affordable.

“I wanted to address amputees in the low-income bracket; to create a hand that doesn’t cost a fortune, but that works similarly to a real hand,” said Dr. George Vicatos. “Because the alternative for this income group is a hook, or a non–functional hand.”

Dr Vicatos (center) and Tenim (right) receiving their Cutting Edge award October 10, Popular Mechanics FutureTech 2014 event

Dr. George Vicatos was Popular Mechanics‘ South African Inventor of the Year in 2011. This past October, Dr. Vicatos and his MSc student Severin Tenim were presented with the Cutting Edge award for the design and development of their new low-cost prosthetic hand–the Tenim Hand–at the Popular Mechanics FutureTech event, held in Cape Town.

“Because locally designed and produced products cost far less than imported equivalents and are delivered faster to the surgeons and hence to the patients, the lower cost is passed on directly to the patient. They’re also more affordable to medical aids,” said Dr. Vicatos of the Tenim Hand.

Dr. Vicatos and Tenim designed the hand to be accessible to the medical community and the patients it serves. Designed for either right- or left-upper limb amputees, the hand is a “mechanical prosthetic” that utilizes a metal cord to control the fingers and thumb’s grip and release functionality. It is able to be positioned open or partially or fully closed. A provisional patent was filed in July 2014 in the UK.

“The hand has a metal cord at the wrist that is either released or pulled in a direction parallel to the fingers. By pulling the cord, the fingers will grip until the hand is closed. The cord works together with a knob, adjacent to the fifth metacarpal (little finger). When the knob is manually rotated or pushed the fingers become locked in position. The thumb is attached by a swivel to rotate and move either towards or away from the fingers,” reads the hand’s technical description.

The cords are attached to a harness, worn across the back, with the shoulder’s movements controlling the pull function. Each individual finger is able to be moved separately from the others, rather than closing or opening the entire hand at once. “There is no other mechanically operated device that is as close to the anatomical function of the hand as this,” said Dr. Vicatos.

Once the design was set, Dr. Vicatos and Tenim sent the files to UCT for 3D printing, then assembled it upon receipt back at UCT.

As UCT project engineer Johan Els explained the build process, 3D printing was utilized to create a “sacrificial part” from polystyrene, which was then covered with a ceramic slurry. The polystyrene was melted out, leaving the ceramic part as a mold in which to pour nylon.

The hand design is not yet finalized, but is clearly on its way to becoming part of the options available to South African amputees.

“The younger generation doesn’t want the ‘glove’ look, or a hand that’s trying to look real when it’s fake,” says Dr. Vicatos. “They want to enhance the fact that they have something artificial – and the mechanics inside this are quite beautiful, so there will be an option to have a transparent window that shows them off.”

What do you think of the Tenim Hand? Does this design stand out to you compared to other prosthetic designs? Let us know your thoughts in the Tenim Prosthetic Hand forum thread over at 3DPB.com.