Multi-scale tarsal adhesion kinematics of freely-walking dock beetles

Abstract

In this experimental study, living dock beetles are observed during their free upside-down walk on a smooth horizontal substrate. Their weight is balanced by the adhesion of hairy structures present on their tarsomeres. The motions involved in the attachment and detachment of these structures were characterized by simultaneously imaging the beetle from the side at the body scale, and from the top at the scale of a single tarsal chain. The observed multi-scale three-dimensional kinematics of the tarsi is qualitatively described, then quantified by image processing and physically modelled. A strong asymmetry is systematically observed between attachment and detachment kinematics, in terms of both timing and directionality.

Rupture of a Liquid Bridge between a Cone and a Plane

“…For example, beetles possess hairy pads and secrete some liquid at the tip of each hair to form temporary bridges with the substrate. [8][9][10][11] Liquid bridges are therefore ubiquitous in nature. 12 The trend to miniaturization requires to handle even smaller micro-components: they must be picked, placed with high accuracy and then released.…”

Inter‐ and intraspecific differences in leaf beetle attachment on rigid and compliant substrates

“…Both the structure and performance of tarsal attachment devices in these beetle species are well described (e.g. Peressadko & Gorb, ; Schuppert et al ., ; Voigt et al ., , ; Bullock & Federle, , ; Gorb & Gorb, ; Clemente et al ., ; Hosoda & Gorb, ; Prüm et al ., ; Gernay et al ., , ; Zurek, Gorb & Voigt, ). Both species bear similar spatula‐shaped, lanceolate and filament‐shaped tarsal adhesive setae in males (♂♂) and females (♀♀), and additional setae with discoid terminal tips present only in males (Stork, ; Pelletier & Smilowitz, ) (Fig.…”

Liquid secretion and setal compliance: the beetle's winning combination for a robust and reversible adhesion

“…Footprints of this secretion have been found for all insect groups studied to date [18]. It suggests that there is one capillary bridge between each setal tip (of surface area S ∼ 25µm 2 [19,20]) and the substrate (Fig. 1b).…”

“…In controlled pad kinematics, maximum friction forces can be one order of magnitude higher than maximum adhesive forces [44]. A few tens of setae already generate enough friction to stop the proximal leg motion during attachment [20]. Moreover, in upside-down free walk, setae in contact do not often slide significantly [20].…”

“…A few tens of setae already generate enough friction to stop the proximal leg motion during attachment [20]. Moreover, in upside-down free walk, setae in contact do not often slide significantly [20]. It suggests that the tips experience large static friction (positive intercept of about 75 kPa in the relation between shear stress and shear rate) that cannot be explained by the hydrodynamic lubrication of a newtonian fluid [45,18].…”