Medical Device Daily

It sounds like something from the far off future a piece of technology maybe available only in the next century or so.

But a type of computerized bracing/suit system designed by Israeli consultant Taga (Tel Aviv, Israel) for Argo Medical Technologies (Haifa, Israel) could become a reality in the here and now. And it could give some paralyzed patients the ability to leave their wheelchairs behind and achieve a greater level of mobility.

The device is called ReWalk, a light, wearable, brace-support suit featuring DC motors at the joints, rechargeable batteries, an array of sensors, and a computer-based system that the paralyzed patient can use control to stand and walk. The company calls it a sort of "powered exo-skelton." And with ReWalk, its developers hope to end the 200-year monopoly of the wheelchair.

"In simple terms, it is a walking device for people who cannot move their legs," Assaf Barel, a Taga design engineer told Medical Device Daily via email. "It enables the disabled person to sit, stand up, walk and climb stairs.

The inventor is Amit Gofer, a quadriplegic paralyzed as the result of an accident. He founded and owns Argo "and intends to commercialize" ReWalk, Barel said, with the subcontracting effort being carried out by Taga.

ReWalk is currently undergoing clinical trials, and the company is pointing to commercial release some time in 2009.

Here's how it works.

"The product is made up of an exoskeleton and includes four electro-mechanical 'muscles' located on the users' legs, one at each hip and knee joint," Barel said. "The legs are propelled forwards and backwards in a normal walking fashion. The system is controlled by a microcontroller at each muscle and by a central master controller which is fed by the user who wears a tilt-sensor on his torso and pressure sensors on the soles of his feet."

Users wear a backpack device that fits snuggly and unobtrusively underneath the patient's clothes. They select the activity they want via remote control and a sensor on the chest determines the torso's angle, guiding braces on the legs to move forward or backward to maintain balance.

The suit's unobtrusiveness was developed deliberately in order to help eliminate the stigma a person using the device might feel, a stigma all too often faced by the wheelchair-bound.

The upper-body motions are analyzed and used to trigger and maintain walking, known as gait patterns, through complex alogorithms.

Barel explained further: "The batteries are located on the backpack. A wireless keyboard on the user's forearm is used to choose the desired operation (sit, stand up, walk and climb stairs). A tilt sensor is located on the chest harness. When the user leans forward, the tilt sensor sends commands to the main computer located in the back-pack and the computer send signals to the electrical motion systems. In order to avoid falling sidewise and for longitudinal stability, the user uses crutches."

Taga was able to determine the calculations and determine variables for the device through the use of software provided by U.S. firm SolidWorks (Concord, Massachusetts).

SolidWorks simplified the design iterations and helped ensure accuracy as engineers constantly refined the concepts to accommodate variables such as leg brace length, joint angle range, and the amount of pressure the joints can withstand.

Barel said that Taga engineers used SolidWorks' mass properties functionality to see exact weight calculations as they designed the exoskeleton to be light enough to maneuver. The companies COSMOSXpress allowed engineers to test the strength and durability of different load-bearing components to ensure the exoskeleton would hold up when users bend, stand up and climb stairs.

Hardly understating the fact, Barel told MDD that there are "a lot of challenges to design something that imitates a human walking, including universal fit for a broad range of user height and weight measurements, as well as a low profile that is both contemporary and user friendly. SolidWorks enabled us to be creative in addressing all of these challenges. The finished product is strong, compact, lightweight and works like a human body."

But the device does more than just offer people the opportunity to walk. It also helps to alleviate other possible health concerns of the paralyzed, both physical and psychological, resulting from the loss of use of their legs.

"These people need the psychological advantage of being able to interact with others at the same eye-level," Barel said. "Leg motion improves blood circulation and prevents pressure sores," a common problem for paraplegics.

It also enables cost savings by enabling many people with disabilities to enter or return to the workforce, averaging $120,000 per year for each person, according to estimates by Argo. And the company notes that the device saves additional dollars by avoiding the need for a variety of environmental modifications frequently necessary for the disabled.

"The ReWalk is truly a product that will have a significant impact on people's lives," said Rainer Gawlick, SolidWorks' VP of worldwide marketing. "Making ambulatory mobility a reality for those with lower limb disabilities is a huge medical advance and one that we at SolidWorks are proud to be a part of."

Argo was founded in 2001, and in 2006 the company joined the Technion (Haifa, Israel) Incubator.