Soft Exosuit Uses Artificial Muscles to Reduce Walking Effort

Researchers in China have developed a prototype soft exosuit that utilizes artificial muscles to assist hip movement, potentially reducing the energy required for walking without bulky traditional motors. The 4.2-pound wearable device fits around the waist and thighs, functioning like a harness.

In a study published in Science Advances, six healthy adults participating in a treadmill test used an average of 13.9% less energy when the exosuit's assistance was active compared to walking without it. Sensors also indicated reduced activity in the participants' leg muscles during powered assistance.

Motor-Free Assistance

Unlike conventional exoskeletons that often rely on rigid motors, gearboxes, or compressed air systems, this soft exosuit employs flexible, artificial muscles made from dielectric elastomers. These materials change shape when subjected to an electric field. Researchers modified the material's molecular structure and arranged thin layers into fibers bundled together to generate sufficient pulling force. Straps then transfer this force to the wearer's hips and thighs, aiding in forward leg movement.

The suit is described as "motor-free" because it lacks traditional motors and gearboxes, instead using a compact battery and electrical system to power the artificial muscles. This design aims to allow for more natural body movement compared to rigid exoskeletal frames.

Early Testing and Potential Applications

During the treadmill trials, participants walked under three conditions: without the suit, with the suit's assistance turned off, and with the assistance active. The metabolic testing system measured oxygen consumption, and leg sensors tracked muscle activity. The observed reduction in energy use and muscle exertion suggests a potential benefit for individuals who experience increased fatigue when walking.

Researchers suggest that such a device could eventually support older adults, individuals recovering from injuries, or those with age-related changes in leg strength, allowing them to remain active for longer periods. The design's less intimidating appearance, with artificial muscles resembling cords integrated into clothing, might also be more appealing than heavier, rigid robotic suits.

Challenges and Future Development

Despite promising early results, the soft exosuit remains an experimental system. Key areas for future development include extending battery life without significantly increasing weight, improving the control system to automatically adapt to changes in walking speed, and addressing challenges like uneven terrain. The dielectric elastomer actuators typically require high voltages, necessitating robust insulation and extensive safety testing for any consumer product.

Further research is also needed to assess the long-term durability of the artificial muscles, their performance in different environmental conditions like sweat and varying temperatures, and their response to repeated bending during daily activities. Clinical trials involving older adults and individuals with mobility challenges are planned to determine the suit's safety, effectiveness, and optimal support levels for diverse user groups. The current study did not focus on fall prevention or stability.

No consumer price or release date has been announced for the soft exosuit.