"Four or two kilos": artificial muscle fiber preparation has a new trick

the power of letting a good "hemp rope" automatically unwrevers?
On July 12, Ray Baughman, a professor at Texas State University in Dallas, usa, and collaborators from Wuhan University in China, among others, published an innovative method of artificial muscle fiber preparation that covers the active material as a shell on the outside of the carrier fiber, thus more effectively increasing the mechanical output density and rate of artificial muscle fibers.
, Baughman and others have proposed the use of the curling technology to prepare artificial muscle fibers, which can be rotated and stretched. Subsequently, researchers from Nan kai University, Fudan University, Donghua University, Suzhou Institute of Nanotechnology and Nano-Bionics of the Chinese Academy of Sciences and other institutions have realized artificial muscle fiber preparation based on this technology in different material systems.
this publication is another improvement in preparation technology for teams such as Baughman.of fiber products that people see in their daily lives are mostly processed with certain additions. If you open a rope made of multiple fibers, the diameter of the rope expands and becomes larger.
" diameter direction becomes thicker and the axis direction becomes shorter. If these fibers recede and recover automatically, this process produces mechanical energy. "The paper's lead author, Alan A. G. McDiamid Nami Center member Mujiko explains. From this example, it is understood that artificial muscle fibers work.
with the help of the object material, to achieve the maximum recoverability of fiber dispersion, regression, need to find the right driving method, the choice of suitable materials and efficient structure. The preparation of high-performance artificial muscle fiber materials has long been a challenge that researchers hope to overcome. In different application scenarios, the different driving methods and materials to match and find the optimal solution, is the same as "undersea needle hunting."
artificial muscle fibers are driven in a variety of ways, such as gas-driven, thermal and electrochemical drives. The energy generated in different ways is passed to the yarn, causing it to change in volume. In this process, the change of yarn is the key to mechanical production, and the angle of a single fiber is closely related to the degree of yarn. In addition, if the material that simulates muscle movement is lighter, the energy consumed by overcoming its own mass is greatly reduced, thus increasing energy output.
long-term exploration, baughman's team found that the outer layer of artificial muscle fibers is the main part of the mechanical energy output, while the fibers in the center of the yarn contribute little to the mechanical energy conversion process.
they also found that the long time it takes for gases to transmit energy, whether thermal or electrochemical, to the inside of the yarn is a major reason for limiting the response speed of artificial muscle fibers.in order to solve the above problems, the team proposed a new structural model -- the active object material originally filled in the whole fiber is concentrated in the outer layer of the yarn carrier, thus forming a shell structure. The active shell material produces volume expansion triggered by a variety of driving methods, which allows the reactive refractive of the muscle fibers and the production of mechanical energy.
Mu Jiuke told China Science Daily that according to different triggers, the team selected a variety of active materials, including polymers and carbon nanotube fibers, as shell layers of artificial muscle materials.
Baughman said: "It is also very important to choose the right shell thickness, if the shell layer is too thick, the internal yarn will be difficult to solve, reduce the mechanical output of artificial muscles, if too thin, the internal core yarn will cause the shell material cracking and deformation, which will affect the circulation stability of artificial muscles." "
addition, Mu Jiuke et al. had an important finding in their experiments: when preparing shell materials, they had to keep them in a gel state." If the outer shell material is too dry, it will break up during the addition process, and in order to maintain elasticity, we have added some solvents to the material that can maintain elasticity. Mr Mukko said.
results show that the shell-driven artificial muscle material has great advantages in response speed and output power density, whether it is gas-driven, thermal-driven or electrochemically driven.
" electrochemically triggered conditions, the unit mass mechanical power of artificial muscle fibers using shell structure can reach 1.98 W/g, which is more than 40 times that of human muscles. "The task force summarizes this in the article., the team did one more thing -- choosing lower-cost commercial fibers instead of carbon nanotube fibers.
Mu Jiuke told reporters that carbon nanotube yarn itself is expensive, a considerable number of types of single grams can be hundreds of dollars. The experimental results show that under the same driving conditions, artificial muscles with shell structure and commercial fiber material also show high mechanical output, which can save the preparation cost of artificial muscles.
" new artificial muscle preparation technology, which replaces carbon nanotube yarns with inexpensive commercial fibers, is attractive in the development of intelligent structural materials such as robots and self-contained fabrics. Baughman said. In addition, the immersion method used in the study to coat the active material is a common and mature method in industry, providing the possibility for large-scale commercial use of the material.
future, the team will also explore other substances that can be used as shell materials. "A lot of material that changes in volume under external stimulation can be used as shell material." Baughman said.
" artificial muscles not only provide mechanical output, but also with sensing, feedback and other functions, which is one of our future research directions. Mr Mukko said.
relevant paper information: