Artificial Muscle Supports 4,000x Weight and Stretches 12x Length

Key Takeaways

1. Researchers at UNIST created a new soft artificial muscle that can switch between being soft and strong.
2. The muscle can hold up to 4,000 times its weight when rigid and stretch up to 12 times its original length when flexible.
3. The innovation addresses a key challenge in soft robotics, combining flexibility with strength using a “dual cross-linked” polymer network.
4. Magnetic microparticles are incorporated for precise movement control through an external magnetic field, allowing a wide range of stiffness.
5. The muscle shows high performance with an actuation strain of over 86.4% and a work density 30 times greater than human muscle tissue.

A team of researchers, headed by Professor Hoon Eui Jeong at UNIST, has created a new kind of soft artificial muscle. This innovative muscle can change from being soft and bendable to being tough and strong. This breakthrough addresses a significant challenge that has hindered advancements in soft robotics. The findings have been published in the journal Advanced Functional Materials. Remarkably, a sample weighing 1.25 grams can hold up to 4,000 times its weight when rigid and can stretch up to 12 times its original length when flexible.

Solving a Major Challenge

The newly developed actuator aims to tackle a core issue in soft robotics: artificial muscles are often either very flexible but weak or strong yet stiff. The team at UNIST managed to create a solution by designing a “dual cross-linked” polymer network. This innovative structure utilizes strong, permanent covalent bonds to maintain mechanical strength, while also incorporating dynamic physical interactions that can be changed with heat, allowing for flexibility.

Advanced Control Mechanisms

Additionally, the researchers mixed in magnetic microparticles within the polymer, which allows for precise manipulation of the muscle’s movements using an external magnetic field. This design enables the material to have a broad range of stiffness, varying from 0.213 MPa to 292 MPa.

When the muscle contracts, it achieves an actuation strain of more than 86.4% and a work density of 1,150 kJ/m3. This is an exceptionally high value for a soft artificial muscle and is about 30 times more than that of human muscle tissue. If this new polymer is successfully developed and implemented, we might eventually see much more powerful and flexible humanoid robots.

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