Dean Kamen's "Luke Arm" Prosthesis Receives FDA Approval

Photo: DARPA

The bionic arm created by DEKA Research for DARPA.

human os iconIts creators nicknamed it the "Luke Arm," after Luke Skywalker’s ultra-advanced bionic limb.

Now, after nearly eight years of development and testing, this robotic arm for amputees has been approved for commercialization by the U.S. Food and Drug Administration (FDA).

The "Luke Arm," whose official name is DEKA Arm System, is one of the most advanced robotic prostheses ever built. According to the FDA, this is the first prosthetic arm approved by the agency that "translates signals from a person's muscles to perform complex tasks."

The DEKA Arm was created by famed inventor Dean Kamen and his team at DEKA Research and Development Corp., in Manchester, N.H., as part of DARPA's Revolutionizing Prosthetics program.

The goal of the US $100 million program was developing an advanced prosthetic arm with near-natural control to improve quality of life for amputees. DARPA funded two groups: the DEKA project and another effort led by researchers at Johns Hopkins University.

What makes the DEKA Arm unique is that it can carry out multiple, simultaneous powered movements, and its wrist and fingers can adjust its positions to perform six different user-selectable grips. In addition, force sensors let the robotic hand precisely control its grasp.

"This prosthetic limb system can pick up objects as delicate as a grape, as well being able to handle very rugged tools like a hand drill," Justin Sanchez, a DARPA program manager who oversees the program, told Reuters.

There's no information on availability and price yet. According to DARPA, DEKA plans to "pursue manufacturing and commercial opportunities to bring the arm to market."

Dean Kamen has done just that with previous technologies he invented, notably drug delivery systems and other medical devices. But the market for assistive technologies is challenging because systems tend to be expensive. The hope is DEKA can find a partner to manufacture and market its bionic arm at an affordable cost.

The DEKA Arm, which has similar size and weight to a natural limb, relies on a combination of control inputs. The main signals come from electromyogram (EMG) electrodes, which sense electrical activity on muscles close to where the prosthesis is attached. A computer on the prosthesis receives the EMG signals and interprets them to make the fingers open or close, or change the grip configuration to let the user pick up a coin, for example.

Photo: DARPA

But to perform the complex movements DEKA wanted, the engineers realized they needed additional control inputs. Their solution: special switches on the user's feet. These switches wirelessly transmit signals to the arm's computer, allowing the user to control multiple joints simultaneously.

DARPA released two videos showing a man using the arm to open an envelope and grasp eggs:

DARPA's Revolutionizing Prosthetics program is the brainchild of Dr. Geoffrey Ling, currently the director of DARPA's Biological Technologies Office and a retired military doctor who served in Iraq and Afghanistan.

Dr. Ling started the program in 2006, with the goal of providing upper arm amputees with better prostheses than the conventional hook-type devices that are commonly used (one version, known as the split-hook device, was invented in 1912).

DEKA received $40 million in DARPA funding to develop its arm. Dean Kamen and his engineers set out to use existing technologies and non-invasive control approaches to rapidly build a prototype and improve the design based on feedback from users, including soldiers who had lost their limbs due to combat injuries.

The design evolved significantly since the early prototypes, which IEEE Spectrum featured in 2008. That model had a very robotic appearance. The latest, FDA-approved design still looks robotic but has a semi-transparent cover.

At the South By Southwest festival in March, Dean Kamen gave a brief update on the DEKA Arm. One of the highlights was that dozens of soldiers were testing the prosthesis, he said.

The tests were part of a study funded by the Department of Veterans Affairs with 36 participants, who were fitted with the DEKA Arm and tried to perform common routine tasks such as using keys, preparing food, feeding themselves, and combing their hair.

According to the FDA, the study showed that about 90 percent of participants were able to perform complex tasks with the bionic arm.

"The DEKA Arm System may allow some people to perform more complex tasks than they can with current prostheses in a way that more closely resembles the natural motion of the arm," said Christy Foreman, director of the Office of Device Evaluation at the FDA’s Center for Devices and Radiological Health, in a statement.

After reviewing the study and other data, the FDA approved the DEKA Arm for commercial use. The FDA says the device is indicated for individuals 18 and older who lost their limbs at the shoulder or the mid-upper or mid-lower arm. (It cannot be configured for limb loss at the elbow or wrist joint.)

The DEKA Arm is undoubtedly an advanced piece of technology. But the needs of amputees vary tremendously and what works for one person might not work for another. In fact, the field of prosthetics has seen huge advances in the past half-decade and designs for robotic arms and hands have proliferated. 

On one end of the spectrum you have highly sophisticated prostheses like the ones developed for DARPA, which also include Johns Hopkins' Modular Prosthetic Limb. Other efforts have focused on more affordable robot hands, such as the Touch Bionics i-LIMB and the Bebionic3.

Some experts argue that a bionic arm that really feels natural to the user will only be possible when we have sensors we can connect directly to nerves or when we develop robust and reliable brain-machine interfaces.

For some individuals, however, simpler approaches might be enough—even a DIY device made in a 3D printer might work better than other, more expensive options.

In any case, DEKA showed that with its "Luke Arm" it could transform something that looked like science fiction into a real technology. Now the next challenge will be transforming that technology into a commercially-viable product.

[ DARPA ] and [ FDA ] via [ Reuters ]

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