Analysis and Measurement of Adhesive Behavior for Gecko‐Inspired Synthetic Microwedge Structure

Abstract

has the advantage of controllable (on-off) attachment. [4][5][6] Many researchers have fabricated synthetic micro/nanostructured adhesives inspired by gecko foot hairs and explored adhesion mechanism, [7][8][9] promoting the applications in many fields, such as debris cleaning in space, [10] ground compliant micromanipulators [11][12][13][14] or robotic gripper, [15,16] climbing robot, [17][18][19] and bioinspired surgical graspers. [20] Gecko synthetic adhesives (GSAs) can adhere to the noncooperative targets and provide a strong and controllable adhesion, which will fit more for capturing satellites and removing space debris than traditional rigid capturing or net capturing. [21] Besides, the adhesion method can also be applied in ground compliant micromanipulators, which is safe and gentle for transporting fragile and flexible parts, and easy to be integrated into micromanipulators. Meanwhile, many scientists work on climbing robots with GSAs, which will help emergency workers to find and rescue victims or inspect and repair in dangerous environment. They can be combined in teams to pull large loads. Moreover, in biomedicine, compared with conventional surgical graspers, bioinspired surgical graspers with GSAs have less damage to human tissue.The adhesion mechanism could give us better insight into dry adhesives and promote application in above fields. [22,23] So it is valuable to mention that scholars have gradually realized that the attachment strength and controllable adhesion are dependent on dimensions and deformations of synthetic fibrillary structure induced by normal and shear loads, which can actively control the contact area between the structure and the substrate. [12,[24][25][26] To further explore the adhesion mechanism, many scientists have explored and established the following adhesive models.The physical mechanism of the GSAs has been interpreted from different perspectives. The Johnson-Kendall-Roberts (JKR) model [3] is classic, which was used earlier for the calculation of adhesion force. It assumed a single fiber as a cylinder with spherical tip and ignored the mechanical deformation of the tip. Therefore, the model was more suitable for the fiber of low aspect ratio. Tian et al. [27] proposed a spatula-shaped peel zone model based on intermolecular force, which analyzed theoretically the gecko's locomotion (on-off) mechanism of the attachment (on) and detachment (off). In this model, normal Synthetic microwedge adhesive inspired by gecko has great advantages in its prominent adhesion property and controllability. Clarifying the adhesion mechanism is significant for designing structure and enhancing performance. However, previous investigations have not given a thorough exposition in the adhesion mechanism of microwedge structure, especially, the complex relationship among shear load, contact area, and normal adhesion. In this paper, aiming to clarify the relationship mentioned above, a novel microwedge adhesive representation combined profile-constructed elastic beam model with a peel zone...

Learning from biological attachment devices: applications of bioinspired reversible adhesive methods in robotics

“…4(b) [57], can climb mock-solar panel surfaces using grippers covered with 80 µm anisotropic fibrils [19]. The adhesives are sheared by an opposite clamp mechanism for detachment and attachment, and the cable driving system can enable the load sharing between different adhesive pads [19,57]. Nanjing University of Aeronautics and Astronautics developed gecko robot_7, as shown in Fig.…”

“…The two broad types of bioinspired spine mechanisms are compliant long-flexure spine mechanisms and linearlyconstrained spine mechanisms as shown in Fig. 14 [19,141]. Compliant long-flexure spine mechanisms can be developed through some types of additive manufacturing, which allows the combination of multiple materials, as shown in Fig.…”

“…Compliant long-flexure spine mechanisms can be developed through some types of additive manufacturing, which allows the combination of multiple materials, as shown in Fig. 14(a) [19], or through compliant mechanism with a single material, as shown in Fig. 14(b) [141].…”

“…Many spiny gripers, inspired by birds and lizards, have been designed to generate force closure and provide greater adhesion by combining grasping and hooking such as examples in Fig. 17 [19,132,[150][151][152]. As shown in Fig.…”

“…(iii) They are unable to adapt to an environment with time-varying constraints and complicated topography due to lack of adequate compliance, adhesion, and robustness [19];…”