TECH – A research team at Ulsan National Institute of Science and Technology (UNIST) in South Korea has developed a groundbreaking artificial muscle that can dynamically shift from soft and flexible to rigid and strong lifting objects 4,000 times heavier than itself. This new composite actuator promises to blur the line between soft robotics and traditional rigid systems.
Cited from interesting engineering, the muscle weighs only 1.25 grams yet, when stiffened, can support roughly 5 kilograms (11 pounds). In its relaxed, soft state, it stretches up to 12 times its original length. That dual capability soft when free, rigid under load is enabled through a novel dual cross-linked polymer network combined with magnetic microparticles. The polymers bind through both stable covalent bonds and weaker thermally responsive physical interactions. When stress is applied or a magnetic field is turned on, the physical bonds shift, stiffening the material.
Embedded within the polymer matrix are magnetic particles that respond to external magnetic fields, giving researchers direct control over actuation and stiffness. This magnetic actuation helped demonstrate the muscle’s lifting capability in lab tests.
Key performance metrics are especially impressive. During contraction, the system achieves 86.4% strain more than double what typical human muscle can manage. Its work density is about 1,150 kJ/m³, which is nearly 30 times higher than human muscle tissue. That means this artificial muscle can output a tremendous amount of energy per unit volume.
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Traditional soft artificial muscles often face a tradeoff: flexibility comes at the cost of force, and strong actuators are usually rigid. The UNIST team’s design aims to solve this by integrating structural adaptability and power in a single module. “Our composite material can do both, opening the door to more versatile soft robots, wearable devices, and intuitive human-machine interfaces,” one of the researchers said.
Because of its combination of high flexibility, strength, and energy output, this advanced muscle could lead to robots that are more human-like in movement soft and adaptive in everyday motions, yet able to exert force when needed. Potential applications include prosthetics, wearables, and agile soft robots capable of navigating unpredictable real-world environments.
The development marks a significant step in overcoming a long-standing limitation in robotics: combining dexterity and strength in a single actuator. As calibration methods, durability testing, and integration into complete robotic systems proceed, this technology may become a key component in future generations of robots and assistive devices.
