Spider-Inspired Helically Engineered Fiber-Based Artificial Muscle with Coupled Actuation and Self-sensing Capabilities

Abstract

Currently, the development of artificial muscles that simultaneously possess high sensitivity, high linearity, and self-sensing capabilities remains a significant challenge. Inspired by the spider’s slit organ, a novel carbon nanotube/liquid crystal elastomer (CNTs/LCE) artificial muscle has been developed. This structure integrates a crack-based sensing unit, a helical deformation mechanism, and self-sensing functionality. A monolithic architecture featuring a helical crack sensor was constructed, which maintains high sensitivity while achieving a large deformation range. In this configuration, the helical structure serves to "kill two birds with one stone": it acts as a sensor that significantly enhances the strain capability, while also functioning as a twisted helical artificial muscle. Furthermore, the introduced crack structure markedly improves sensing sensitivity. When combined with a porous structure that enhances deformability, and utilizing the helical geometry to further amplify the deformation amplitude (up to 110%) and improve response linearity (R² = 0.99), the overall performance is significantly advanced. Based on this novel architecture, a corresponding theoretical model was established and finite element simulations were performed using COMSOL. Moreover, the incorporation of CNTs improved the uniformity of thermal distribution within the LCE fiber. It was confirmed that the CNTs-coated LCE fiber exhibits a more homogeneous internal temperature distribution, resulting in enhanced actuation performance—specifically, a 19.2% increase in contraction stroke and an 8-second reduction in contraction time. Additionally, the CNTs network itself possesses excellent sensing properties, enabling real-time and precise perception of multiple mechanical stimuli, including stretching, contraction, and compression. Consequently, the CNTs/LCE fibrous artificial muscle is capable of monitoring its own motion states in real time and can also serve as a circuit protector to safeguard electronic systems.

Keywords

Wearable sensors / Artificial muscle / Self-sensing functionality / Crack structure / Helical twist structure

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Funding

The National Key Research and Development Program of China(2022YFB3807103)

Tianjin Key Discipline of Material Physics and Chemistry and Scientific Developing Foundation of Tianjin Education Commission(2018ZD09)

The National Natural Science Foundation of China(12504249)

National Natural Science Foundation of China(52350120)

The Fundamental Research Funds for the Central Universities(63171219)

Beijing-Tianjin-Hebei Basic Research Cooperation Project(J230023)

Anhui Provincial Science and Technology Innovation Tackling Program(No. 202423i08050057)

RIGHTS & PERMISSIONS

Donghua University, Shanghai, China