Artificial muscle flexible actuators can convert external stimuli into mechanical motion, and have important applications in flexible exoskeletons, prosthetics, soft robots, and other fields. The spiral wound yarn constructed with carbon nanotube fibers has the advantages of light weight, good electrical and thermal conductivity, etc., and is often used to make artificial muscles. Among them, the direct power-on drive is convenient for operation and simple in structure. However, electrothermally driven yarns are often accompanied by disadvantages such as slow cooling and poor frequency performance, which limit their practical use.
Recently, Dr. Hu Xinghao from the Institute of Intelligent and Flexible Mechatronics of Jiangsu University, in cooperation with the research group of Academician Ray Bowman of the University of Texas at Dallas, proposed a new sheath-core electrothermally driven artificial muscle (Figure 1). , specifically using high mechanical strength organic fibers as the core and carbon nanotubes composited with silica gel as the sheath. During the high-frequency driving process, due to the different thermal conductivity of the sheath and core materials, the heat exchange between the fiber and the air mainly occurs in the sheath layer (Fig. 2). Therefore, the sheath-core artificial muscle greatly shortens its cooling process and realizes high-frequency driving. The related work was published in Advanced Functional Materials under the title of "Fast Large-stroke sheath-driven electrothermal artificial muscles with high power densities". The first author and corresponding author of the paper is Dr. Hu Xinghao of Jiangsu University, and the co-corresponding author is Ray. Academician Bowman.
The research results have been authorized Chinese invention patent (patent number: 201910576614.7). This work was supported by the National Natural Science Foundation of China (52105057), the National Postdoctoral Fund (2021M691307) and the Science and Technology Program of Jiangsu Province (BK20200916).
Fig.1 Schematic diagram of sheath-core electrothermally driven carbon nanotube fiber artificial muscle
Fig.2 Output performance and cooling simulation of sheath-core electrothermally driven artificial muscle
Fig.3 Crawling robot made by sheath-core electrothermal artificial muscle
One of the latest advances in nanotube fiber artificial muscles. In the past year, the team has transformed the "bipolar" driving of artificial muscle smart materials into "unipolar" driving through the strategy of polyelectrolyte functionalization. At the same time, the abnormal phenomenon that the driving performance of artificial muscles decreases with the decrease of capacitance is found. (Science 371, 494–498 (2021)), this important breakthrough solves the capacitive dependence of artificial muscle actuation performance and provides a new theoretical basis for the subsequent design of high-performance actuators with non-toxic and low driving voltage.
Article link: https://onlinelibrary.wiley.com/doi/10.1002/adfm.202200591
