The gecko can achieve flexible climbing on various vertical walls and even ceilings, which is closely related to its unique foot adhesion system. In the past two decades, the mechanism of the gecko adhesion system has been studied in-depth, and a verity of gecko-inspired adhesives have been proposed. In addition to its strong adhesion, its easy detachment is also the key to achieving efficient climbing locomotion for geckos. A similar controllable adhesion characteristic is also key to the research into artificial gecko-inspired adhesives. In this paper, the structures, fabrication methods, and applications of gecko-inspired controllable adhesives are summarized for future reference in adhesive development. Firstly, the controllable adhesion mechanism of geckos is introduced. Then, the control mechanism, adhesion performance, and preparation methods of gecko-inspired controllable adhesives are described. Subsequently, various successful applications of gecko-inspired controllable adhesives are presented. Finally, future challenges and opportunities to develop gecko-inspired controllable adhesive are presented.

This paper proposes the design and experiment of a bioinspired wall-climbing robot with spiny arrays. Inspired by the Serica orientalis Motschulsky's tarsal system, a spiny structure is designed, and the robot's foot which has two grippers using the structure is designed. An inchworm-like gait is employed and its trajectory is planned. The robot's foot as well as the whole prototype is fabricated and tested. It is verified that the foot has remarkable adhesive ability and the robot can scale vertical and inverted rough surfaces including the ceiling.

This paper presents a leg-wheel wall-climbing robot utilizing bio-inspired spine feet, which is called LWbot (a leg-wheel robot). It is a 14 mm long and 57 g weight robot. It is capable of climbing both vertical brick surfaces and penetrable surfaces, such as curtains and polystyrene foam boards. It can climb not only upward, but also downward. The climbing speed on vertical curtain is up to 9.5 cm/s. LWbot consists of a passive wheel and two groups of legs which are equipped with modified Chebyshev four-bar linkages and compliant spine feet. A single motor drives the four-bar linkages to move continuously to achieve the movement of insects' climbing, and the “D” shaped trajectory of foot tip makes the miniature spines easy to penetrate in (or cling on) and pull off the surfaces. Moreover, the compliant foot mechanism inspired by the structure and mechanism of the tarsal chain in the cockroach makes the attachment more reliable.