Natural muscles show tensile actuation and realize torsional rotation by combining with the skeleton, which integrate with sensing and signaling function in a single element to form a feedback loop. The currently developed artificial muscle and sensing devices always work upon external stimuli, and a separate controlling and signal transmission system is needed, increasing the complexity of muscle design. Therefore it is highly desired to develop flexible and compact fiber artificial muscles with large strain for advanced soft robotic systems. In this paper, twisted elastomer fiber artificial muscles with tensile and torsional actuations and sensing function by a single electric signal are developed, by using twisted natural rubber fiber coated with a buckled carbon nanotube sheet. The twisted natural rubber fiber can be electrothermally actuated to show contraction and rotation by entropic elasticity. The buckled carbon nanotube sheet can transmit electric current, and the contact area between the buckled carbon nanotube sheets increased during actuation, resulting in resistance decrease by thermo-piezoresistive effect. A feedback circuit was designed to connect or disconnect the electric current by measuring the resistance change to form a feedback loop to control on/off of the muscle. The current study provides a new muscle design for soft robotics, controllers, and human-machine integration.

中文翻译：

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熵弹性的拉伸和扭转弹性体纤维人造肌肉，通过热电电阻感测单个电信号的应变和旋转

天然肌肉通过与骨骼结合显示拉伸驱动力并实现扭转旋转，骨骼与感测和信号功能集成在一个元素中，形成反馈回路。当前开发的人造肌肉和感测设备总是在外部刺激下起作用，并且需要单独的控制和信号传输系统，这增加了肌肉设计的复杂性。因此，非常需要开发用于高级软机器人系统的具有大应变的柔性且紧密的纤维人造肌肉。在本文中，通过使用涂有屈曲的碳纳米管片的天然橡胶加捻纤维，开发了具有拉伸和扭转致动并具有单个电信号感应功能的加捻弹性体纤维人造肌肉。绞合的天然橡胶纤维可以通过电热致动，以通过熵弹性表现出收缩和旋转。屈曲的碳纳米管片可以传输电流，并且屈曲的碳纳米管片之间的接触面积在致动期间增加，导致电阻因热压阻效应而减小。通过测量电阻变化来设计一个反馈电路来连接或断开电流，以形成一个反馈回路来控制肌肉的开/关。当前的研究为软机器人，控制器和人机集成提供了新的肌肉设计。由于热压阻效应导致电阻降低。通过测量电阻变化来设计一个反馈电路来连接或断开电流，以形成一个反馈回路来控制肌肉的开/关。当前的研究为软机器人，控制器和人机集成提供了新的肌肉设计。由于热压阻效应导致电阻降低。通过测量电阻变化来设计一个反馈电路来连接或断开电流，以形成一个反馈回路来控制肌肉的开/关。当前的研究为软机器人，控制器和人机集成提供了新的肌肉设计。