Bioinspired dry adhesives: From challenging surface adhesion to controllable release

ABSTRACT Bioinspired dry adhesive technology, with the gecko as a central model, leveraging its unique advantages of residue-free adhesion, reversibility, and self-cleaning, holds significant potential for applications such as gripping and climbing. However, its practical deployment faces two pivotal challenges: achieving robust adhesion on non-ideal surfaces, including rough, curved, or those under extreme environmental conditions, and realizing efficient and on-demand detachment mechanisms for gripping and climbing tasks. This review systematically surveys recent advances through these two lenses, covering a broad spectrum of bioinspired adhesion strategies that draw not only on the gecko but also on insights from octopus, beetle, and tree frog attachment systems. The mechanical origins of adhesion degradation on complex surfaces are first analyzed, including true contact area loss, elastic energy penalty, stress concentration, and structural instabilities. Design strategies for robust adhesion are then elaborated, covering hierarchical structures, stiffness-gradient architectures, external-field-assisted regulation, and backing-layer optimization, alongside solutions tailored for underwater, contaminated, and epidermal interface environments. For detachment control, major reversible methods such as mechanical load manipulation, external physical field (electric, magnetic, thermal) actuation, and interfacial wetting regulation, are compared in terms of response speed, energy consumption, and reliability. Applications in soft grippers, climbing robots, and unmanned aerial vehicles are outlined, with real-world performance demands discussed. This review provides guidance for constructing bioinspired dry adhesive systems that integrate extreme-environment reliability with intelligent, controllable detachment, and offers a perspective on future developments.