Wearable exoskeleton helps children to walk at duPont Hospital’s pediatric engineering lab

WREXBy Christi Milligan

It’s a long walk from the light-filled atrium of Alfred I. duPont Hospital for Children’s new expansion to the east wing that houses the Pediatric Engineering Research Laboratory (PERL). It’s a distance marked by dimming overheads, manual doors, and gilded, framed artwork notably different from the hospital’s celebrated, modern additions.

But in these quiet quarters, researchers and engineers are developing advances in therapies, sensors, and orthotic mechanisms, including their most lauded creation, the Wilmington Robotic Exoskeleton (WREX). It’s a wearable upper-limb device with linear elastic bands that give multidimensional movement to little arms limited by orthopedic and neuromuscular disabilities.

Senior Research Engineer Dr. Tariq Rahman heads the four-member PERL team. Their research lab is part workshop, part tech space, where the engineering behind devices like the WREX involves erector sets, desk light arms, and a 3D printer. Mathematical equations reminiscent of high school trigonometry class are critical in transforming the engineering process from model to a finished product like the WREX — years in the making.

“By definition, researchers are working on answers to problems that may or may not work,” explained Rahman, who has worked at A.I. for 25 years. But when it does work, it’s life changing for doctor and patient.

Today nearly 150 individuals have received the WREX through A.I., which holds the patent for the device. Another 500 have received one through Jaeco Orthopedic, which manufactures the metal parts of the WREX and is licensed to sell it.

Rahman said it is the lab’s crowning achievement, and the PERL space offers a window into the device’s evolution, which began when physical therapists noted that existing devices for patients with arm atrophy were cumbersome and heavy.

“We wondered, How do you move arms with rubber bands and springs?” said Rahman, who took to the erector set and began to build. “This kind of works,” he said of the bands that were part of his early models — nods to the movement of desk lamps or dental lights that feature a tension-spring arm.

Essentially, the WREX — using mechanical linkage powered by rubber bands —removes the gravity that weighs limbs down, according to Rahman. It can be attached to a body jacket for children who walk or may be attached to a wheelchair for non-ambulatory kids.

It allows children and adults with weak arm muscles to move their arm in space with minimal effort, even specific and direction motion that enables them to play, feed themselves, and brush their hair.

Rahman has a picture of one special teen playing drums with the aid of the WREX.

As Rahman and his associates finessed the exoskeleton, hoping to make it lighter and more streamlined, they turned to their in-house 3D printer, which allowed them to fabricate lightweight pieces for the device. The plastic pieces enabled the smallest and youngest patients, some just 2 years old, to utilize the WREX.

Today those plastic components are printed en masse at PERL and stored in plastic tubs ready for building and filling orders. The introduction of the 3D printer in the lab was transformative, and Rahman said the ability to produce actual pieces in minutes has minimized the turn-around time for parts.

“The printer was great — it gave us a lot of flexibility in realizing things that are in our head. You can print it out, play with it. That’s a big plus,” he said.

In medical circles, the value of 3D printing is colossal. According to Bill Decker, chairman of The 3D Printing Association, a global trade organization, Invisalign and Cochlear are two of the largest medical-based companies actively employing 3D printing for their signature products.

At PERL, Rahman and his associates even printed a foot from the CAT scan of a child with orthopedic issues. That foot — a “bony skeleton” — was given to the patient’s surgeon prior to surgery.

The team fits about three kids each month for the WREX, which costs about $3,000 and takes an average of two-to-three months to process.
“It’s not fast enough,” said Rahman, who’d like to see it widely available.

“Insurance … they don’t have a medical code for this, and so Jaeco struggles with getting a third party to sell and maintain them,” he said. “It’s like a catch-22. Until you show the WREX works for many kids, they’re not going to pay for it. But, if families can’t pay for it, you can’t show that it works well for many kids.”

Decker said insurance is the driver of the medical future of 3-D printing and it will, in part, determine how mainstream this tech-based science becomes.

“Once the insurance industry says, ‘This is a best practice,’ they’ll (hospitals) be forced to have it,” said Decker.

As Rahman presents papers about the WREX at medical conventions in the U.S. and abroad, the PERL researchers are still tweaking aspects of the present model, hoping to take it to another level as demand increases.

“We want to make it invisible,” said Rahman. In one sunny corner of a workroom where custom fittings take place stand child-sized mannequins. Working with a nurse who has a talent for sewing, the team is hoping to hide the WREX under special, lightweight shirts.

“It’s tricky — we don’t want to make it a struggle and we want to optimize function,” said Rahman.

At the lab Rahman said the team works on a number of projects simultaneously, some of them prompted by physical therapists who approach them about options for rehab. Others stem from engineering topics, and many are generated from physicians— like the doctors at A.I. who wondered about a way to track just how often scoliosis patients were wearing the braces so critical to their treatment.

Rahman partnered with Newark tech firm Creative Micro Design to develop a small chip, not much bigger than a quarter, embedded into the brace. The device responds to temperature and records the brace-wear time and pattern of brace-wear, according to Rahman, who sees crossover possibilities in the engineering behind almost everything.

“I was in the car with my son … and there was an ashtray,” Rahman said. “I kept studying it, the springs and the way it snaps shut.”

Like other engineering functions, its simple function may well be put to use at PERL, where Rahman hopes one day he and his team could develop a WREX-like device for patients who can’t walk.

“I’m thinking all the time about this stuff,” he said. ♦

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