Researchers in China have developed a soft robotic suit that could one day make walking easier for older adults and people with mobility challenges. The experimental exosuit uses thin artificial muscles to assist the hips, replacing the heavy motors and gearboxes found in conventional robotic exoskeletons. A study published in the peer-reviewed journal Science Advances describes a prototype that weighs about 4.2 pounds and fits around the waist and thighs like a lightweight harness.
In a small treadmill test involving six healthy adults, the suit reduced the energy needed for walking by an average of 13.9 percent when the powered assistance was active. Sensors also showed lower muscle activity in the legs, indicating the volunteers’ muscles had to work less to complete each step. The results suggest that a wearable device of this kind could help people stay active longer as their leg strength declines with age.
The soft exosuit takes a fundamentally different approach from earlier exoskeletons, which typically rely on rigid motors, compressed air systems, pumps, valves, and air tanks. Those components can make the devices heavy, noisy, and restrictive to natural movement. The new design uses flexible, muscle-like fibers positioned near each hip. As a person walks, the fibers pull at the right moment in the stride to help move the leg forward. Straps transfer that pulling force from the artificial muscles to the wearer’s hips and thighs, allowing the suit to move with the body rather than enclosing the legs inside a rigid frame.
The term “motor-free” refers to the absence of traditional motors and gearboxes, but the suit still relies on a compact battery pack and an electrical power system to activate the artificial muscles. These muscles are made from a rubber-like material called a dielectric elastomer, which changes shape when exposed to an electric field. Researchers have studied dielectric elastomers for years, but earlier versions lacked the force needed to help move a human leg and were often too bulky for a comfortable wearable device.
Wei Yu and his colleagues at Hebei University of Technology modified the molecular structure of the material to improve its performance. They rolled thin layers into long fibers and then grouped several fibers into bundles. This arrangement works somewhat like human muscle, where many smaller fibers pull together to create greater force. The team also created modular connectors that allow adding more fibers when an application requires additional pulling power. According to the university, the actuators completed more than 100,000 cycles during laboratory testing, though longer studies are needed to show how well the materials hold up during daily wear.
The current prototype remains an early research system with several limitations. Battery life restricts how long the suit can provide assistance, and the researchers aim to develop future versions that operate longer without adding much weight. The control system also needs to respond automatically when a person speeds up or slows down. Walking on uneven ground or climbing slopes would present additional challenges. Voltage is another hurdle: dielectric elastomer actuators often require more than 1,000 volts. Although the current stays very low, any wearable consumer product would need strong insulation and extensive safety testing. Researchers will also need to study how the fibers respond to sweat and changing temperatures over time.
While the initial tests are promising, the study involved only six healthy adults walking on a treadmill in a controlled setting. Dedicated studies with older people and individuals with mobility challenges are still necessary. Balance is another important consideration; the current study focused on energy expenditure rather than fall prevention or stability. Future clinical trials will need to determine who can use the suit safely and how much support each person requires.
A lightweight device that reduces walking effort could have broad applications. Walking through a large grocery store, spending the day with family, or recovering from surgery could become more manageable for people who experience fatigue or weakness. The soft exosuit’s design may also feel less intimidating than a rigid robotic frame, as the artificial muscles resemble cords built into clothing and the supporting straps fit close to the body. However, the prototype is still a research system, and it may be years before a commercial version is available. The researchers plan to refine the technology and conduct larger trials to move closer to a practical assistive device for everyday use.
