Soft Microdenticles on Artificial Octopus Sucker Enable Extraordinary Adaptability and Wet Adhesion on Diverse Nonflat Surfaces

Abstract

Bioinspired soft devices, which possess high adaptability to targeted objects, provide promising solutions for a variety of industrial and medical applications. However, achieving stable and switchable attachment to objects with curved, rough, and irregular surfaces remains difficult, particularly in dry and underwater environments. Here, a highly adaptive soft microstructured switchable adhesion device is presented, which is inspired by the geometric and material characteristics of the tiny denticles on the surface of an octopus sucker. The contact interface of the artificial octopus sucker (AOS) is imprinted with soft, microscale denticles that interact adaptably with highly rough or curved surfaces. Robust and controllable attachment of the AOS with soft microdenticles (AOS-sm) to dry and wet surfaces with diverse morphologies is achieved, allowing conformal attachment on curved and soft objects with high roughness. In addition, AOS-sms assembled with an octopus-arm-inspired soft actuator demonstrate reliable grasping and the transport of complex polyhedrons, rough objects, and soft, delicate, slippery biological samples.

Biomimetic Structure and Surface for Grasping Tasks

“…They prestretched the patch and exposed it to UV/ozone to obtain wrinkles and achieved 55 kPa in a dry condition and 40 kPa in an underwater condition. By designing adjustable cavities to increase the pressure difference inside and outside the suction cup, and utilizing secondary molding on the suction cup surface to create smaller-scale suction cups, Hwang et al [ 65 ] enhanced the suction cup’s adaptability to rough surfaces while improving its controllability ( Figure 7 e,f). This ultimately resulted in achieving a maximum normal force of 29 N in dry conditions and 49 N underwater at an input pressure of 80 kPa.…”

“… Ref. Bioinspired Shape Feature Length a (μm) Target Curvature Target Surface Roughness Main Loading Direction Environment [ 1 , 11 , 63 , 64 , 65 , 66 , 69 , 72 , 73 , 74 , 75 , 110 ] Octopus Sucker Sucker radius: 0.1~10 5 > a << a Normal Underwater/Air [ 20 , 26 , 32 , 41 , 43 , 49 , 111 , 112 , 113 , 114 ] Gecko Wedge shaped Height: 10 1 ~10 3 > a << a Tangential Air/Vacuum …”

“…Reprinted with permission from Ref. [ 65 ]. Copyright 2022, Hwang et al ( g , h ) Suction cup surface fabricated by the electrowetting effect.…”

Adhesion performance of magnetically responsive surfaces under wet conditions

“…At present, many schemes have realized reversible wettability and adhesion by external stimuli, such as photostimuli, 8,9 pH, 10 gas, 11,12 magnetic fields, [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] etc. Among these stimuli, magnetic fields offering the advantages of remote controllability, instantaneous response and convenience have been widely investigated, and most studies have focused on the droplet manipulation and adhesion controlled by magnetic fields.…”