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

Gilet, Tristan; Heepe, Lars; Lambert, Pierre; Compère, Philippe; Gorb, Stanislav N.

doi:10.1016/j.cois.2018.08.002

Cited by 14 publications

(16 citation statements)

References 60 publications

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“…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.…”

Section: Introductionmentioning

confidence: 99%

Rupture of a Liquid Bridge between a Cone and a Plane

2019

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In this work, a systematic experimental study of the rupture of an axially symmetric liquid bridge between a cone and a plane was performed, with focus on the volume distribution after break up. A model based on the Young-Laplace equation is presented and its solutions are compared to experimental data. Cones and conical cavities with different aperture angles were used in our experiments. We found that this aperture influences the potential pinning of the contact line, the meniscus shape and therefore the liquid transfer. For half aperture angles α < 70°, where no pinning was observed, the liquid bridge slips off from the cone and almost no transfer to the cone is observed. However, at α > 70°, contact line pinning on the cone induces a net liquid transfer to the cone at rupture. In the case of conical cavities, a maximum of liquid transfer is observed for at α =110°. The distance at which the rupture of the liquid bridge occurs is also discussed. The model can fairly predict the transfer ratio and the rupture height of the liquid bridge.

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Section: Introductionmentioning

confidence: 99%

Rupture of a Liquid Bridge between a Cone and a Plane

2019

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“…This hierarchical structure of the pretarsal attachment system of spiders is different from the structure of fibrillary adhesive systems of insects, e.g. in beetles and earwigs, which are made up of shorter, unbranched setae on the tarsi (Haas and Gorb, 2004;Gilet et al, 2018).…”

Section: Discussionmentioning

confidence: 82%

Adhesion of Individual Attachment Setae of the Spider Cupiennius salei to Substrates With Different Roughness and Surface Energy

2021

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Dynamic adhesion is a key ability for animals to climb smooth surfaces. Spiders evolved, convergent to geckos, a dry adhesive system made of setae branching into smaller microtrichia ending as spatulae. Several previous studies concentrated either on the whole adhesive claw tuft on the spider´s foot that consists of attachment setae or on the single adhesive contact elements, the microtrichia with spatula-shaped tips. Here, the adhesion of single setae of the spider Cupiennius salei was examined and the morphology of the pretarsus and the fine structure of the setae were studied in further detail. Using individual setae fixed to force sensing cantilevers, their adhesion at different contact angles with a glass substrate was measured as well as their adhesive performance on substrates with different roughness and on smooth surfaces with different surface energies. The results show an individual variability of the adhesive forces corresponding to the seta morphology and especially to the seta tip shape. The tip shapes of the setae vary largely even in neighboring setae of the pretarsal claw tuft that comprises approximately 2,400 setae. Regarding surface energy of the substrate, the adhesion force on hydrophobic polytetrafluoroethylene was 30% of that on a hydrophilic glass substrate, which points to the importance of both van der Waals interactions and hydrogen bonds in spider adhesion.

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“…The higher viscosity exhibited by a fluid with this profile during events with very low or no shear rate, such as clinging on inclined surfaces or ceilings, would be ideal for slip prevention (Bullock et al, 2008;Dirks et al, 2010;Dirks and Federle, 2011). However, the shear rate applied by this system at average beetle walking speed (∼5 mm/s) and with a biomimetic fluid layer 100 nm thick (a conservative estimate of natural fluid thickness) (Gorb et al, 2012;Gilet et al, 2018) would be well above the rate necessary for the fluid to exhibit a constant, low viscosity like that of pure squalane (Supplementary Figure 4) (Thornham et al, 2008;Dirks and Federle, 2011). Thus, this fluid would provide a resistance to sliding without increasing the effort required to resume movement.…”

Section: Discussionmentioning

confidence: 99%

“…Many previous studies have shown that this fluid is vital to the ability of insects to walk and climb without slipping and sliding on various natural and artificial surfaces (Gorb, 2001;Gorb, 2002, 2009;Langer et al, 2004;Gorb et al, 2008Gorb et al, , 2010Busshardt et al, 2012;Hosoda and Gorb, 2012;England et al, 2016). However, a consensus explanation for precisely how this fluid aids both strong adhesion and rapid release does not currently exist (Gilet et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Multi-Technique Investigation of a Biomimetic Insect Tarsal Adhesive Fluid

2021

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There is substantial motivation to develop novel adhesives which take advantage of the superior adhesive strength and adaptability of many natural animal adhesives; however, the tools typically used to study these mechanisms are incapable of determining the precise interactions of molecules at an adhesive interface. In this study, a surface specific, order sensitive vibrational spectroscopy called sum frequency generation (SFG) is, for the first time, combined with multiple bulk characterization techniques to examine a novel, simple biomimetic adhesive fluid inspired by tarsal fluid of insects. Insects perform complex adhesive demands, including sticking, climbing vertically and running upside-down with little difficulty. Thus, we hypothesize that both bulk and surface specific properties of the fluid contribute to the success of this wet adhesive mechanism. SFG spectra of biomimetic emulsion exhibited similar hydrocarbon organization on hydrophobic and hydrophilic substrates to natural beetle fluid previously studied with the same method. Bulk characterization techniques indicated that the emulsion had a shear-thinning profile with the ability to enhance traction forces during climbing and low surface tension ideal for surface wetting on the majority of natural surfaces. Multi-technique comparisons between emulsion and pure squalane revealed that a hydrocarbon only based fluid could not replicate the traction promoting properties of the emulsion. We conclude that the insect tarsal fluid adhesive mechanism relies upon contributions from both surface-specific properties optimizing traction force and bulk properties promoting rapid surface wetting and maintaining pull-off force for fast detachment.

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

Cited by 14 publications

References 60 publications

Rupture of a Liquid Bridge between a Cone and a Plane

Rupture of a Liquid Bridge between a Cone and a Plane

Adhesion of Individual Attachment Setae of the Spider Cupiennius salei to Substrates With Different Roughness and Surface Energy

Multi-Technique Investigation of a Biomimetic Insect Tarsal Adhesive Fluid

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