A study published in the latest issue of the American magazine Science shows that a team of researchers from the United States, China and other countries has developed a new type of artificial muscle, whose average contraction force is 40 times that of human muscle, and the cost is controllable, easy to mass produce, and has broad application prospects.

Fibrous artificial muscle is a mechanical energy conversion material for future intelligent robots. Its principle is that materials such as carbon nanotubes undergo multiple twisting processes called "twisting" and then contract or stretch under the drive of gas, thermal energy or electrochemical energy to simulate muscle movement.

Researchers from the University of Texas at Dallas, China's Donghua University and other institutions wrapped a layer of active shell material composed of polymers on the outside of various yarns, so that they do not need to activate all the yarns, but only need to activate the shell, and use the volume change of the shell to quickly and effectively convert the input energy into mechanical energy.

The first author of the paper, Mu Jiuke of the University of Texas at Dallas, told Xinhua News Agency that this shell-driven artificial muscle has largely solved the shortcomings of the previous artificial muscle's inner layer materials consuming more input energy and low energy conversion efficiency.

Research shows that under electrochemical triggering conditions, a shell-driven artificial muscle composed of materials such as carbon nanotubes and nylon yarns has a contraction force that is 40 times that of human muscles, far exceeding some previous artificial muscles.

The researchers also demonstrated artificial muscles with natural silk, bamboo fiber yarn and electrospinning as inner layer materials, which also showed good mechanical energy conversion capabilities. Ray Bowman, the corresponding author of the paper and director of the Nanotechnology Institute at the University of Texas at Dallas, pointed out that using low-cost commercial fibers instead of expensive carbon nanotubes will make this artificial muscle easier to apply to robots, smart clothing and other aspects.

In this study, Zhu Meifang, Wang Hongzhi and others from Donghua University in China developed a smart fabric based on shell-driven artificial muscles, which can automatically increase its porosity when the ambient humidity is high. The smart clothing made of this fabric will bring better comfort to the human body when worn.

The paper also demonstrated a shell-driven artificial muscle that can sense and respond to external glucose content, indicating that this artificial muscle has application potential in the field of drug sustained release.