Tiny robot muscle lifts 4,000 times its weight in lab breakthrough

Researchers at the Ulsan National Institute of Science and Technology (UNIST) in South Korea have developed a novel artificial muscle that can transition between soft and flexible to rigid and strong states, overcoming a major limitation in soft robotics. This tiny muscle, weighing just 1.25 grams, can stiffen under heavy loads to provide structural support and then soften to allow contraction and flexibility. Its core innovation lies in a dual cross-linked polymer network combining covalent bonds for strength and thermally responsive physical interactions for flexibility, along with embedded surface-treated magnetic microparticles that enable precise control via external magnetic fields. The artificial muscle can lift up to 5 kilograms—about 4,000 times its own weight—and stretch up to 12 times its original length when softened. It achieves an exceptional strain of 86.4% during contraction, more than double that of human muscles, and a work density of 1,150 kJ/m³, which is 30 times higher than human tissue. This