Engineers have created a new type of artificial muscle that combines the best of two worlds: it is soft enough to mimic human skin but can stiffen in an instant to lift heavy loads. Developed by researchers at the Ulsan National Institute of Science and Technology (UNIST) in South Korea, this magnetic material can support tensile loads up to 1,000 times its own weight. By mixing special polymers with magnetic particles, the team built a “muscle” that changes its stiffness on demand, opening the door to safer and stronger robots.
How the magnetic muscle works
The core innovation lies in a composite material that blends a shape-memory polymer with ferromagnetic particles. This mix gives the muscle a dual personality, allowing it to switch properties based on temperature and magnetic fields.
Shape-memory polymers and magnets
The base of the muscle is a shape-memory polymer. These plastics can be deformed and then return to their original shape when heated. The researchers embedded tiny neodymium-iron-boron particles—powerful magnets—into this polymer. These particles allow the material to be controlled remotely using an external magnetic field, while the polymer provides the structural ability to lock and unlock its shape.
Switching between soft and hard
The muscle operates by changing its temperature. When heated (for example, by a laser), the polymer bonds loosen, and the material becomes soft and stretchy, like a rubber band. In this state, the magnetic field can easily stretch, bend, or twist the muscle into a new position. When the material cools down, the polymer crystallizes and locks into that new shape, becoming rigid. The difference is drastic: the material becomes over 2,700 times stiffer in its rigid state compared to its soft state.
Unmatched strength and flexibility
Most soft robots today rely on pneumatic systems (air pressure) or simple silicone, which limits how much weight they can carry. This new magnetic composite breaks those limits by offering both high payload capacity and extreme flexibility.
Lifting 1000 times its weight
In its rigid state, the artificial muscle is incredibly strong. Tests showed it could withstand tensile stress (pulling force) equivalent to 1,000 times its own weight. When compressed, it could support even more—up to 3,690 times its weight. This allows a small strip of the material to hold heavy objects that would crush or deform standard soft robotic actuators.
Dampening vibrations with hydrogel
To make movement smooth and precise, the team added a layer of hydrogel to the muscle. This double-layer design helps absorb vibrations that often occur when robots move quickly or stop suddenly. This stability allows the muscle to perform delicate tasks with high precision, even when lifting heavy loads.
Future robots and wearables
This technology solves a major hurdle in robotics: building machines that are safe to touch but strong enough to do real work.
Safer human-robot interaction
Because these muscles can be soft and compliant, they are ideal for “soft robots” that work alongside people. Unlike rigid metal motors, a soft magnetic muscle poses little risk of injury if it accidentally bumps into a human. This makes them perfect for wearable devices, such as exoskeletons that boost a worker’s strength, or advanced prosthetic limbs that feel more natural than current models.
This development parallels other recent innovations, such as water powered humanoid robot muscles, which also aim to replace rigid motors with more biological-like actuators. As components like these evolve, we move closer to a true robotics revolution where machines can navigate complex environments autonomously.
Sources & related information
Nature Communications – Multifunctional magnetic muscles for soft robotics – 2024
Researchers at UNIST detail the creation of a magnetic composite artificial muscle that integrates phase-change polymers with ferromagnetic particles to achieve high load capacity and variable stiffness.
UNIST News – New Study Unveils Strong and Soft Artificial Muscles – 2024
The university press release explains how the team achieved a stiffness variation of over 2,700 times and demonstrated the muscle’s ability to withstand automotive-level loads.
Techno-Science – Video: this artificial muscle lifts 1000 times its weight – 2024
A summary of the discovery highlighting how the material combines the flexibility of skin with the strength of steel for applications in surgery and prosthetics.
Recent progress in the field
For context on how fast this field is moving, earlier breakthroughs in robotics have also focused on artificial muscles, paving the way for the high-load capabilities seen in this new study.
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