Hercules made muscle fibers inspired by human muscles


May 25, 2023

(Nanowerk News) Prof. Group Sang Ouk Kim at KAIST has developed a new type of artificial muscle fiber based on a liquid crystal-graphene elastomer composite. This new artificial muscle has been highlighted as the closest system to human muscle among those reported to the scientific community to date, while demonstrating up to 17 times higher strength.

The research has been published in Natural Nanotechnology (“Muscle human-inspired single fiber actuator with reversible percolation”).

It is a well-known fact that in nature animal muscles are deformed by a process of nervous excitation, resulting in mechanical movement. Several research fields, including robotics and artificial organs, have developed technologies that aim to replicate this type of movement. However, most of these technologies have so far relied heavily on mechanical devices.

To address this long-standing challenge, the development of artificial muscles that can mimic the flexible movements of natural muscles, exploiting suitable combinations of soft materials, has received significant attention recently. Unfortunately, a significant limitation for most artificial muscles is their restrictive deformation stroke, which is still slow and weak compared to that observed in animal muscles. In addition, to produce a strong mechanical movement, extra energy storage processes such as twisting or winding are required before use.

Professor Kim’s research team has created a new material composition that incorporates high-quality graphene fillers into a liquid crystal elastomeric matrix; this enables large reversible contractions similar to those in animal muscle, along with remote control through the use of lasers, while achieving a work capacity 17 times higher and power density values ​​6 times higher than that of natural human muscle. Based on the powerful contraction of an artificial strand of muscle, the team demonstrated an interesting and versatile bioinspired locomotion structure, including successfully lifting a 1-kilogram dumbbell and an artificial inch worm winning a race with its living partner. Mechanisms of actuation and collateral signaling of changes in the structural organization of human skeletal muscle myofibrils (top) and graphene liquid-crystal elastomeric composite fibers (bottom) Mechanisms of actuation and collateral signaling of changes in the structural organization of human skeletal muscle myofibrils (top) and graphene liquid-crystal elastomeric composite fibers (bottom). (Image: KAIST)

“Recently actively developed artificial muscles have excellent actuation properties, but so far none have demonstrated the complete range required for practical application,” says professor Sang Ouk Kim, corresponding author of this work and a distinguished scholar in science. materials science. “This research is a significant starting point for developing practical artificial muscle materials that can be implemented in industrial robotics, wearable devices, and contribute to non-face-to-face scientific and technological advances after the 4th industrial revolution,” he also mentioned.

“Our new artificial muscle fiber also exhibits unprecedented reversible percolation of the graphene filling network under stable actuation along the alignment direction, resulting in in-situ monitoring of actuation through electrical switching and effective gain of mechanical properties especially in the contracted actuation state. ,” said Dr In Ho Kim, first author and now a postdoctoral fellow in the Department of medical engineering at Caltech. “This exciting behavior is realized by a thoughtful optimization for the intimate intermolecular interactions between filler and matrix, and we have performed a series of in-depth characterizations in this study to verify these molecular-level interactions in macro-scale structure,” he said.


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