Bioinspired adhesive patch with octopus vulgaris micro-sucker and hexagonal tree-frog pad structures

Our artificial bioinspired adhesive patch is inspired by two different biological creatures in one design, which consists of a densely packed hexagonal tree-frog pad embedded with vulgaris octopuses' microscopic suckers. This work focuses on the creation of a new microscopic sucker design that takes inspiration from the structure of real octopus' suckers to improve adhesion and overcome potential issues related to the existing micro-sucker design. Theoretical analysis, simulations, and experimental studies demonstrated that this new-designed microscopic sucker exhibits robust adhesion under various conditions (dry, moist, underwater, and under oil). Several factors that influence adhesion performance, including compressive preloading force, time of attachment, number of contact cycles, and surface roughness, are investigated. It showed stronger adhesion than previous sucker designs and proved its ability to remain attached for up to 24 h, withstand a large number of contact cycles, and adhere to high- and low-roughness surfaces. It reached 57.3–116.4 kPa of normal adhesion strength and 29.8–93.47 kPa of shear adhesion strength. Based on these results, our adhesive patch design could pave the way for future skin-conforming patches in medical devices.