Reviewed by Lexie CornerApr 24 2025
A recent study published in Engineering presents a significant development in dry adhesive technology. Researchers from Xi’an Jiaotong University, including Duorui Wang, Hongmiao Tian, Jinyou Shao, and their team, have developed a self-adaptive core-shell dry adhesive with a "live core." This adhesive shows high-strength adhesion even under non-parallel contact conditions.
(a) The entire structure and cross section of the macroscopic core-shell adhesives; (b) The section morphology of the core-shell adhesives; (c) A brief description of the mechanism of the core-shell adhesives; (d) The adhesion performance of the core-shell adhesives under misalignment situation (2°); (e) Demonstration of the self-adaptation and anti-overturning property of the core-shell adhesives. Image Credit: Duorui Wang et al.
Gecko-inspired adhesion technology, which utilizes van der Waals forces, has potential applications in robotics. However, non-parallel contact—a frequent challenge in real-world engineering scenarios—can weaken adhesion strength, compromising stability and operational efficiency. Despite the high theoretical adhesion potential of artificial dry adhesives, consistent performance has been difficult to achieve due to these non-parallel contact limitations.
The newly developed adhesive is inspired by the soft muscle and rigid bone in a gecko’s sole. It features a mushroom-shaped adhesion tip at the top that uses van der Waals forces for effective grip. It also incorporates a core-shell structure at the base to regulate interface stress.
Unlike traditional core-shell designs with a static "dead core," this adhesive includes a dynamic "live core" that rotates within the soft shell, resembling the function of skeletal joints. This rotation allows for stress equalization at the contact surface, enabling the adhesive to adapt to misalignments and improve performance in non-parallel contact situations.
Using materials such as polydimethylsiloxane (PDMS) and silicone rubber, the researchers fabricated the adhesive and assessed its microstructure, mechanical properties, and adhesion performance under both aligned and misaligned conditions.
The self-adaptive core-shell adhesive demonstrated adhesion strength up to 100 times greater than traditional homogeneous structures when subjected to non-parallel contact. It also exhibited strong anti-overturning capabilities, which are crucial for stable gripping in robotic applications.
Finite element analysis (FEA) was used to investigate the adhesion mechanism. The FEA model showed that rotation of the rigid core within the core-shell structure significantly reduces the effective misalignment angle, optimizing stress distribution at the contact interface. This improved alignment and stress regulation contribute to the adhesive’s enhanced performance.
The adhesive’s performance was quantitatively assessed, demonstrating its superior capabilities under various preload conditions. The adhesive maintained strong and consistent adhesion even in high-temperature and water-rich environments.
To improve performance, the researchers optimized the adhesive’s structural design by studying the impact of factors such as the stiffness of the soft shell and rigid core, the geometric positioning of the rigid core, and its size on the core’s rotational angle and overall adhesion strength.
This self-adaptive core-shell dry adhesive offers significant potential for object manipulation, particularly on sloped or irregular surfaces. Its ability to adapt to non-parallel contact and resist overturning makes it well-suited for precision tasks, such as optical component assembly.
This technology marks a significant advancement in the development of gecko-inspired adhesion-based devices and systems.
Journal Reference:
Wang, D., et al. (2025). Self-Adaptive Core-Shell Dry Adhesive with a “Live Core” for High-Strength Adhesion under Non-Parallel Contact. Engineering. doi.org/10.1016/j.eng.2024.12.035.