Structure and mechanical properties ofOctopus vulgarissuckers

Abstract

In this study, we investigate the morphology and mechanical features of Octopus vulgaris suckers, which may serve as a model for the creation of a new generation of attachment devices. Octopus suckers attach to a wide range of substrates in wet conditions, including rough surfaces. This amazing feature is made possible by the sucker's tissues, which are pliable to the substrate profile. Previous studies have described a peculiar internal structure that plays a fundamental role in the attachment and detachment processes of the sucker. In this work, we present a mechanical characterization of the tissues involved in the attachment process, which was performed using microindentation tests. We evaluated the elasticity modulus and viscoelastic parameters of the natural tissues (E ∼ 10 kPa) and measured the mechanical properties of some artificial materials that have previously been used in soft robotics. Such a comparison of biological prototypes and artificial material that mimics octopus-sucker tissue is crucial for the design of innovative artificial suction cups for use in wet environments. We conclude that the properties of the common elastomers that are generally used in soft robotics are quite dissimilar to the properties of biological suckers.

Underwater attachment using hairs: the functioning of spatula and sucker setae from male diving beetles

“…In the circular seta, k i is approximately 115 N m 21 and is caused by restoration of the sucker and stalk to their original shapes, and a greater k f of approximately 180 N m 21 is associated with further deformation, mainly from the sucker. If compressive resistance has a similar magnitude to that of extension at initial pulling, the much greater k i found in circular setae implies that a greater force is required to preload the setae before there is complete attachment.…”

Unveiling the morphology of the acetabulum in octopus suckers and its role in attachment

“…The infundibulum and acetabulum communicate via an orifice (indicated by 'o' in figure 1a). The infundibular surface is characterized by radial and circumferential grooves and is completely encircled by an epithelial rim ('rim' in figure 1a) [13,14,19,20]. The structure of the acetabulum has long been debated.…”

“…This technology has been validated in Octopus vulgaris and has the potential to be successfully applied to other octopus species. In recent years, several studies have been conducted on sucker anatomy and morphology, helping to address the previous lack of information and identifying several unique traits [13][14][15]. In this work, we briefly describe the gross morphology of octopus suckers based on the available literature, present the first histological analyses of the suckers of several octopus species and discuss the proposed mechanism of attachment of the octopus sucker: the protuberance in the acetabular roof discovered in all the investigated octopus could be the key to realizing a smart and energy-efficient attachment.…”

Anchoring like octopus: biologically inspired soft artificial sucker

“…Biomimetic aspects of octopus suckers have been long studied; the morphology and physiology of octopus suckers and possibilities for biomimetic replication of suckers have been investigated [12,16,[21][22][23][24][25], with particular emphasis on the transition from hard to soft in the mechanical stiffness of sucker [21][22][23][24][25], also referred as stiffness gradient 2 design in some relevant literature [30][31].…”