Johns Hopkins Applied Physics Lab aims to build prosthetic arm that can be controlled by the brain

From the Howard County Times in Maryland:

Since World War II, the technology behind prosthetic arms has remained virtually the same.

Those who lost a limb were given a “hook and cable” device that didn’t act much like an arm, or even look like one.

But that’s all beginning to change, thanks in part to some work being done in Howard County.

Engineers at the Johns Hopkins Applied Physics Laboratory in North Laurel are reaching the final stages of a four-year mission to build the most ambitious prosthetic arm yet: an arm that not only looks human, but is also controlled by the mind.

“It’s a truly revolutionary advancement in prosthetics,” says APL’s Michael McLoughlin, the program manager on the project.

The Pentagon’s Defense Advanced Research Projects Agency has spent $100 million on its “Revolutionizing Prosthetics” project, including a $34.5 million grant awarded to the Howard County lab this summer, enabling the scientists to conduct tests with their latest prototype of the arm.

APL’s program has produced two complex prototypes, each advancing the art of upper-arm prosthetics, and its final design, called the Modular Prosthetic Limb (MPL), is its latest breakthrough.

The Pentagon’s project in prosthetics grabbed national attention last year, when an arm designed in a two-year period was put on display by DEKA Research and Development Corp., a New Hampshire company that created the Segway, an electric car and other high-profile inventions.

DEKA’s bionic arm was called “Luke” (after the “Star Wars” character Luke Skywalker) and hurtled the technology of prosthetics into the future.

Using the “Luke” arm, amputees could pick up a grape, drink a soda and open a door.

Those tasks were impossible using the hook that amputees of earlier eras were given.

As amazing as the DEKA arm is, the scientists at the APL say they are working on a breakthrough even bigger.

“This project’s goals are more ambitious,” McLoughlin says.

The DEKA arm looks robotic and requires a foot pedal to work; the MPL arm looks human and will be controlled by the brain, he said.

“The first thing was to make an arm that really looked like a human,” McLoughlin said. “You’d look at the arm and think it was actually the person’s arm. That, in itself, is very challenging.

“We built an arm that was similar in strength and dexterity to a human arm. The arm can curl 50 pounds. We joked that most of the development team can’t do that. That was a tremendous engineering challenge to make all that work.”

Yet simply building the arm wasn’t enough. There was another challenge: How does someone control that arm?

Previous prosthetic limbs operate using switches and pedals, but the engineers at Hopkins saw that as unacceptable.

“That’s not how you use your arm,” he said. “You just reach out and pick something off the table without thinking about it.”

The MPL offers 22 degrees of motion, including independent movement of each finger, in a package that weighs about nine pounds, the weight of a natural limb, the scientists say. Providing nearly as much dexterity as a natural limb, the MPL is capable of unprecedented mechanical agility and is designed to respond to a user’s thoughts.

The human brain continues to send signals to nerves in the shoulder of an amputee when it wants to move an arm, and the engineers want to use those nerves to operate the MPL.

“The amputee thinks about moving their arm, but there’s no where for those signals to go,” McLoughlin said. “We’re able to intercept those signals; interpret what you’re trying to do and make the arm do that motion.”

Within the year, the APL-led team will initiate testing with a high spinal cord injury patient.

“Initially, we targeted the quadriplegic patient population because they have the most to gain,” McLoughlin said.

In the next two years, the team hopes to test the systems and neural interface technology in five patients.

One of the goals of the testing will be to demonstrate that the system can operate with a patient’s thoughts and provide sensory feedback, restoring the sensation of touch, McLoughlin said.

The team will develop implantable microchips used to record brain signals and stimulate the brain. They will also conduct trials testing implantable neural interfaces — or brain chips — to control a prosthesis.

The effort will be done in collaboration with other universities, including Pittsburgh, CalTech, Chicago and Utah.

“The goal is to enable the user to more effectively control movements to perform everyday tasks, such as picking up and holding a cup of coffee,” McLoughlin said.