In a warehouse that looks like a cross between a mad inventor's garage and a climbing gym, a pair of mechanical legs hangs from the ceiling on ropes. With the quiet whir of four motors, one in each hip and knee, the legs take a step, then another and another. This is an exoskeleton walking suit, and it is taking the hundreds of thousands of steps that regulators demand to prove that it's no mere toy but a reliable medical device, one that just might change the lives of people who thought they'd never again rise from a wheelchair.
The Berkeley, Calif., warehouse is the home of Ekso Bionics (formerly known as Berkeley Bionics), a young company that's about to step out onto the world stage. Early this year the company will begin selling its Ekso suit to rehab clinics in the United States and Europe, to allow patients with spinal cord injuries to train with the device under a doctor's supervision. By the middle of 2012, the company plans to have a model for at-home physical therapy.
When you don the Ekso, you are essentially strapping yourself to a sophisticated robot. It supports its own 20-kilogram weight via the skeletal legs and footrests and takes care of the calculations needed for each step. Your job is to balance your upper body, shifting your weight as you plant a walking stick on the right; your physical therapist will then use a remote control to signal the left leg to step forward. In a later model the walking sticks will have motion sensors that communicate with the legs, allowing the user to take complete control.
"We took the idea of the external skeleton, and we added nerves in the form of sensors and motors that represent your muscles and computers that represent your brain," says Eythor Bender, CEO of Ekso Bionics.
The company began its evolution in 2005 with the ExoHiker, an exoskeleton that allows able-bodied people to carry 90 kg (about 200 pounds) with minimal exertion. The company's engineers at first thought it would take 5 kilowatts to power such an exoskeleton, which would have meant bulky batteries and motors. The breakthrough was a redistribution of weight that reduced the power requirements by three orders of magnitude. A later system, the load-carrying HULC (Human Universal Load Carrier), was licensed to Lockheed Martin Corp. for military development in 2009, and Ekso Bionics' engineers began looking for a new direction. Their energy-efficient devices, they realized, left them with a "power budget" that could be spent on moving the user's legs. That's when paraplegic people became the company's target customers.
A few other companies around the world are bringing out exoskeletons for people with disabilities, but Ekso Bionics' push in 2012 may give it a market advantage. Ten top U.S. rehab clinics have already signed up for the first batch of production units.
One of the first devices will go to Mount Sinai Hospital, in New York City, where Kristjan T. Ragnarsson, chairman of the department of rehabilitation medicine, has treated spinal cord patients for 40 years. His patients' priorities have never changed. "The first thing they want to know is whether they will walk again," says Ragnarsson. "As their physician, I always have to address that question."
Over the years he has told his patients about the latest inventions, from stiff air-filled garments to devices that electrically stimulate the muscles, but all these contraptions proved too difficult for the patients to operate. "They were completely exhausted after just a few steps," he says.
Ragnarsson thinks the Ekso can succeed where so many others failed, because the powered device does most of the labor for the patient. "I'm optimistic, actually, that this will work," he says. "I think my patients will be able to stand up and take a few steps and face the next person directly on!"