Bioinspired Directional Adhesives Enable High Stiffness Layer Jamming in Soft Actuators *
Zhihuan Wang, Linsen Xu, Mingming Wang, Liangzhi Ye, Zhihua Zhang
Abstract
Soft actuators are inherently flexible and compliant, traits that enhance their adaptability to diverse environments and tasks. However, their low structural stiffness can lead to unpredictable and uncontrollable complex deformations when substantial force is required, thereby compromising their load-bearing capacity. This work proposes a novel layer jamming method that uses bioinspired directional adhesives as interlayer films to adjust the stiffness of soft actuators. The mechanical behavior of a single tilted fibril was analyzed using the energy method to determine the adhesion force of the adhesives. The directional adhesive was designed under the guidance of the adhesion force model. Testing under various loads and directions revealed that the tilted characteristic of fibrils can enhance the adhesion force in its grasping direction. A tunable stiffness actuator using directional adhesives (TSADA), was developed with these adhesives serving as interlayer films. The stiffness model of TSADA was derived by analyzing its axial compression force. The results of stiffness experiments indicate that the adhesives serve as interlayer films can adjust the stiffness in response to applied load. TSADA was compared with other typical soft actuators to evaluate the stiffness performance, and the results indicate that TSADA exhibits the highest stiffness and the widest tunable stiffness range. This demonstrates the superior performance of the directional adhesives as interlayer films in terms of stiffness adjustment.
BibTeX
@inproceedings{iros2025_bioinspireddirec,
title = {Bioinspired Directional Adhesives Enable High Stiffness Layer Jamming in Soft Actuators *},
author = {Zhihuan Wang and Linsen Xu and Mingming Wang and Liangzhi Ye and Zhihua Zhang},
booktitle = {IROS 2025},
year = {2025}
}