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Amador GJ, Klaassen van Oorschot B, Sen U, Karman B, Leenders R. Capillary adhesion of stick insects. Ann N Y Acad Sci 2024; 1538:98-106. [PMID: 39091080 DOI: 10.1111/nyas.15195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Scientific progress within the last few decades has revealed the functional morphology of an insect's sticky footpads-a compliant pad that secretes thin liquid films. However, the physico-chemical mechanisms underlying their adhesion remain elusive. Here, we explore these underlying mechanisms by simultaneously measuring adhesive force and contact geometry of the adhesive footpads of live, tethered Indian stick insects, Carausius morosus, spanning more than two orders of magnitude in body mass. We find that the adhesive force we measure is similar to the previous measurements that use a centrifuge. Our measurements afford us the opportunity to directly probe the adhesive stress in vivo and use existing theory on capillary adhesion to predict the surface tension of the secreted liquid and compare it to previous assumptions. From our predictions, we find that the surface tension required to generate the adhesive stresses we observed ranges between 0.68 and 12 mNm - 1 ${\rm m}^{-1}$ . The low surface tension of the liquid would enhance the wetting of the stick insect's footpads and promote their ability to conform to various substrates. Our insights may inform the biomimetic design of capillary-based, reversible adhesives and motivate future studies on the physico-chemical properties of the secreted liquid.
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Affiliation(s)
- Guillermo J Amador
- Experimental Zoology Group, Wageningen University & Research, Wageningen, The Netherlands
| | | | - Uddalok Sen
- Physical Chemistry and Soft Matter, Wageningen University & Research, Wageningen, The Netherlands
| | - Benjamin Karman
- Biology Department, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Rutger Leenders
- Experimental Zoology Group, Wageningen University & Research, Wageningen, The Netherlands
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2
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Grote M, Gorb SN, Büscher TH. The effect of age on the attachment ability of stick insects (Phasmatodea). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:867-883. [PMID: 39076693 PMCID: PMC11285055 DOI: 10.3762/bjnano.15.72] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Accepted: 07/04/2024] [Indexed: 07/31/2024]
Abstract
Many insect species have found their way into ageing research as small and easy-to-keep model organisms. A major sign of ageing is the loss of locomotory functions due to neuronal disorders or tissue wear. Soft and pliable attachment pads on the tarsi of insects adapt to the substrate texture to maximize their real contact area and, thereby, generate attachment during locomotion. In the majority of stick insects, adhesive microstructures covering those pads support attachment. Stick insects do not molt again after reaching the imaginal stage; hence, the cuticle of their pads is subject to continuous ageing. This study aims to quantify how attachment ability changes with age in the stick insect Sungaya aeta Hennemann, 2023 and elucidate the age effects on the material and microstructure of the attachment apparatus. Attachment performance (adhesion and friction forces) on substrates with different roughnesses was compared between two different age groups, and the change of attachment performance was monitored extending over a larger time frame. Ageing effects on the morphology of the attachment pads and the autofluorescence of the cuticle were documented using light, scanning electron, and confocal laser scanning microscopy. The results show that both adhesion and friction forces decline with age. Deflation of the pads, scarring of the cuticle, and alteration of the autofluorescence, likely indicating stiffening of the cuticle, were observed to accumulate over time. This would reduce the attachment ability of the insect, as pads lose their pliant properties and cannot properly maintain sufficient contact area with the substrate.
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Affiliation(s)
- Marie Grote
- Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| | - Stanislav N Gorb
- Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| | - Thies H Büscher
- Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
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3
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Salerno G, Rebora M, Piersanti S, Gorb E, Gorb S. Parasitoid attachment ability and the host surface wettability. ZOOLOGY 2024; 165:126181. [PMID: 38833995 DOI: 10.1016/j.zool.2024.126181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 05/28/2024] [Accepted: 05/31/2024] [Indexed: 06/06/2024]
Abstract
Climbing animals such as geckos and arthropods developed astonishing adhesive mechanisms which are fundamental for their survival and represent valuable models for biomimetic purposes. A firm adhesion to the host surface, in order to successfully lay eggs is necessary for the reproduction of most parasitoid insects. In the present study, we performed a comparative investigation on the attachment ability of four parasitoid species (the egg parasitoid Anastatus bifasciatus (Eupelmidae), the aphid parasitoid Aphidius ervi (Braconidae), the fly pupal ectoparasitoid Muscidifurax raptorellus (Pteromalidae) and the pupal parasitoid of Drosophila Trichopria drosophilae (Diapriidae)) with hosts characterized by a surface having different wettability properties. The friction force measurements were performed on smooth artificial (glass) surfaces showing different contact angles of water. We found that attachment systems of parasitoid insects are tuned to match the wettability of the host surface. Sexual dimorphism in the attachment ability of some tested species has been also observed. The obtained results are probably related to different microstructure and chemical composition of the host surfaces and to different chemical composition of the parasitoid adhesive fluid. The data here presented can be interpreted as an adaptation, especially in the female, to the physicochemical properties of the host surface and contribute to shed light on the coevolutionary processes of parasitoid insects and their hosts.
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Affiliation(s)
- Gianandrea Salerno
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, University of Perugia, Borgo XX Giugno 74, Perugia 06121, Italy
| | - Manuela Rebora
- Dipartimento di Chimica, Biologia e Biotecnologie, University of Perugia, Via Elce di Sotto 8, Perugia 06121, Italy.
| | - Silvana Piersanti
- Dipartimento di Chimica, Biologia e Biotecnologie, University of Perugia, Via Elce di Sotto 8, Perugia 06121, Italy
| | - Elena Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel 24098, Germany
| | - Stanislav Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, Kiel 24098, Germany
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4
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Thomas J, Gorb SN, Büscher TH. Comparative analysis of the ultrastructure and adhesive secretion pathways of different smooth attachment pads of the stick insect Medauroidea extradentata (Phasmatodea). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:612-630. [PMID: 38887530 PMCID: PMC11181264 DOI: 10.3762/bjnano.15.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/08/2024] [Indexed: 06/20/2024]
Abstract
The mechanism by which insects achieve attachment and locomotion across diverse substrates has long intrigued scientists, prompting extensive research on the functional morphology of attachment pads. In stick insects, attachment and locomotion are facilitated by two distinct types of smooth cuticular attachment pads: the primary adhesion force-generating arolium and the friction force-generating euplantulae. They are both supported by an adhesive secretion delivered into the interspace between the attachment pads and the substrate. In this study, we analysed and compared internal morphology, material composition and ultrastructure, as well as the transportation pathways in both adhesive organs in the stick insect Medauroidea extradentata using scanning electron microscopy, micro-computed tomography, light microscopy, and confocal laser scanning microscopy. Our observations revealed structural differences between both attachment pads, reflecting their distinct functionality. Furthermore, our results delineate a potential pathway for adhesive secretions, originating from exocrine epidermal cells and traversing various layers before reaching the surface. Within the attachment pad, the fluid may influence the viscoelastic properties of the pad and control the attachment/detachment process. Understanding the material composition of attachment pads and the distribution process of the adhesive secretion can potentially aid in the development of more effective artificial attachment systems.
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Affiliation(s)
- Julian Thomas
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Thies H Büscher
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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Dos Santos PG, Dos Santos EG, de Carvalho Guimarães I, Cardoso CAL, Lima-Junior SE, Antonialli-Junior WF. Hydrocarbons in Formicidae: influence of chemical footprints on ant behavioral strategies. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2024; 111:24. [PMID: 38634907 DOI: 10.1007/s00114-024-01908-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 03/16/2024] [Accepted: 03/19/2024] [Indexed: 04/19/2024]
Abstract
When an insect walks, it leaves chemical cues that derive from the arolium, a tarsal structure. These cues may contain important information about other species that occur in their community and can then mediate interactions of competition, predation, and information about resources with ants from their own colony. The compounds of these cues are released into the substrate in the form of chemical footprints. There are still few species studied, and little is known about the behavior of ants regarding these signals and how they use them in their interactions. Therefore, the aim of this study was to assess the behavioral strategy of different ant species when confronted with chemical footprints left by other ants, as well as identify their compounds and their relationship with the cuticular hydrocarbon profile. The experiments were performed using a Y-maze, where in one of the arms, there were chemical footprints of their own species or of other species, and the other Y arm was footprint-free. The chemical compounds of footprints and cuticle were analyzed by gas chromatography-mass spectrometry. The results show that foragers of all species detect and respond to the presence of chemical cues in the form of footprints left by other ants. Foragers of all species followed footprints of individuals of the same species both nestmates and non-nestmates; however, Neoponera villosa avoided the footprints of Cephalotes borgmeieri, and C. borgmeieri avoided the footprints of the other two species. The chemical compositions of the cuticle and footprints are related to each other and are specific to each species.
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Affiliation(s)
- Poliana Galvão Dos Santos
- Laboratório de Ecologia Comportamental, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil.
- Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Universidade Federal da Grande Dourados, Dourados, Mato Grosso Do Sul, 79804-970, Brazil.
- Centro de Estudos Em Recursos Naturais, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil.
| | - Elane Galvão Dos Santos
- Programa de Pós-Graduação Ciência E Tecnologia Ambiental, Universidade Federal da Grande Dourados, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
| | - Ingrid de Carvalho Guimarães
- Laboratório de Ecologia Comportamental, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
- Centro de Estudos Em Recursos Naturais, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
| | - Claudia Andrea Lima Cardoso
- Centro de Estudos Em Recursos Naturais, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
| | - Sidnei Eduardo Lima-Junior
- Centro de Estudos Em Recursos Naturais, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
| | - William Fernando Antonialli-Junior
- Laboratório de Ecologia Comportamental, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
- Programa de Pós-Graduação em Entomologia e Conservação da Biodiversidade, Universidade Federal da Grande Dourados, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
- Centro de Estudos Em Recursos Naturais, Universidade Estadual de Mato Grosso Do Sul, Dourados, Mato Grosso Do Sul, 79804-970, Brazil
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6
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Krings W, Gorb SN. Particle binding capacity of snail saliva. J Chem Phys 2023; 159:185101. [PMID: 37955324 DOI: 10.1063/5.0176668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 10/20/2023] [Indexed: 11/14/2023] Open
Abstract
Gastropods forage with their radula, a thin chitinous membrane with embedded teeth, which scratch across the substrate to lose food particles. During this interaction, the risk of loosening particles is obvious without having a specialized mechanism holding them on the tooth surface. As mucus secretions are essential in molluscan life cycles and the locomotion and attachment gels are known to have an instant high adhesion, we have hypothesized that the saliva could support particle retention during feeding. As adhesion of snail saliva was not studied before, we present here an experimental setup to test its particle-binding capacity using a large land snail (Lissachatina fulica, Stylommatophora, Heterobranchia). This experiment was also applied to the gels produced by the snail foot for comparison and can be potentially applied to various fluids present at a small volume in the future. We found, that the saliva has high particle retention capacity that is comparable to the foot glue of the snail. To gain some insight into the properties of the saliva, we additionally studied it in the scanning electron microscope, estimated its viscosity in a de-wetting experiment, and investigated its elemental composition using energy dispersive X-ray spectroscopy reveling higher contents of Ca, Zn and other potential cross-linkers similar to those found in the glue.
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Affiliation(s)
- Wencke Krings
- Department of Cariology, Endodontology and Periodontology, Universität Leipzig, Liebigstraße 12, 04103 Leipzig, Germany
- Department of Electron Microscopy, Institute of Cell and Systems Biology of Animals, Universität Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
- Department of Mammalogy and Palaeoanthropology, Leibniz Institute for the Analysis of Biodiversity Change, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany
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Ingham CS, Engl T, Kaltenpoth M. Protection of a defensive symbiont does not constrain the composition of the multifunctional hydrocarbon profile in digger wasps. Biol Lett 2023; 19:20230301. [PMID: 37909057 PMCID: PMC10618855 DOI: 10.1098/rsbl.2023.0301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/13/2023] [Indexed: 11/02/2023] Open
Abstract
Hydrocarbons (HCs) fulfil indispensable functions in insects, protecting against desiccation and serving chemical communication. However, the link between composition and function, and the selection pressures shaping HC profiles remain poorly understood. Beewolf digger wasps (Hymenoptera: Crabronidae) use an antennal gland secretion rich in linear unsaturated HCs to form a hydrophobic barrier around their defensive bacterial symbiont, protecting it from brood cell fumigation by toxic egg-produced nitric oxide (NO). Virtually identical HC compositions mediate desiccation protection and prey preservation from moulding in underground beewolf brood cells. It is unknown whether this composition presents an optimized adaptation to all functions, or a compromise due to conflicting selection pressures. Here, we reconstitute the NO barrier with single and binary combinations of synthetic linear saturated and unsaturated HCs, corresponding to HCs found in beewolves. The results show that pure alkanes as well as 3 : 1 mixtures of alkanes and alkenes resembling the composition of beewolf HCs form efficient protective barriers against NO, indicating that protection can be achieved by different mixtures of HCs. Since in vitro assays with symbiont cultures from different beewolf hosts indicate widespread NO sensitivity, HC-mediated protection from NO is likely important across Philanthini wasps. We conclude that HC-mediated protection of the symbiont from NO does not exert a conflicting selection pressure on the multifunctional HC profile of beewolves.
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Affiliation(s)
- Chantal Selina Ingham
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Tobias Engl
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
- Department of Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745 Jena, Germany
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Thomas J, Gorb SN, Büscher TH. Characterization of Morphologically Distinct Components in the Tarsal Secretion of Medauroidea extradentata (Phasmatodea) Using Cryo-Scanning Electron Microscopy. Biomimetics (Basel) 2023; 8:439. [PMID: 37754190 PMCID: PMC10526352 DOI: 10.3390/biomimetics8050439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/14/2023] [Accepted: 09/18/2023] [Indexed: 09/28/2023] Open
Abstract
Attachment to the substrate is an important phenomenon that determines the survival of many organisms. Most insects utilize wet adhesion to support attachment, which is characterized by fluids that are secreted into the interface between the tarsus and the substrates. Previous research has investigated the composition and function of tarsal secretions of different insect groups, showing that the secretions are likely viscous emulsions that contribute to attachment by generating capillary and viscous adhesion, leveling surface roughness and providing self-cleaning of the adhesive systems. Details of the structural organization of these secretions are, however, largely unknown. Here, we analyzed footprints originating from the arolium and euplantulae of the stick insect Medauroidea extradentata using cryo-scanning electron microscopy (cryo-SEM) and white light interferometry (WLI). The secretion was investigated with cryo-SEM, revealing four morphologically distinguishable components. The 3D WLI measurements of the droplet shapes and volumes over time revealed distinctly different evaporation rates for different types of droplets. Our results indicate that the subfunctionalization of the tarsal secretion is facilitated by morphologically distinct components, which are likely a result of different proportions of components within the emulsion. Understanding these components and their functions may aid in gaining insights for developing adaptive and multifunctional biomimetic adhesive systems.
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Affiliation(s)
- Julian Thomas
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany; (S.N.G.); (T.H.B.)
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Matsumura Y, Gorb EV, Gorb SN. The tight attachment achieved by the male discoidal setae is possibly a counter-adaptation to the grease layer on female integument surfaces in green dock beetles. J R Soc Interface 2023; 20:20230324. [PMID: 37582406 PMCID: PMC10427193 DOI: 10.1098/rsif.2023.0324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023] Open
Abstract
Green dock beetles Gastrophysa viridula exhibit sexual dimorphism in tarsal attachment setae: females have only pointed, lanceolate and spatula-like setae, while males additionally possess discoidal ones. The sexual dimorphism is probably attributed to the necessity of male discoidal setae to adhere to the smooth back of the female during copulation. We aimed to understand its possible mechanism of attachment with G. viridula. Pull-off forces of both females and males were measured on (i) alive females, (ii) dead and dried females, and (iii) resin replicas of fresh females. The attachment ability tended to increase on dead and replicated female surfaces in both sexes, which indicates that the epicuticular grease layer on the integument of alive intact beetles decreases the attachment. This tendency was prominent in females. The present study clearly showed that in G. viridula discoidal setae enable the males to adhere stronger to female surfaces. The divergent performance found between the sexes differing in their setal composition is probably caused by the stiffness difference between the setae types and by the specific shape of the setal tips. A peculiar reproductive biology in G. viridula is probably attributed to this remarkable divergence of labour in their attachment pads between the sexes.
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Affiliation(s)
- Yoko Matsumura
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
- Department of Systematic Entomology, Graduate School of Agriculture, Hokkaido University, 060-8589 Sapporo, Japan
| | - Elena V. Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N. Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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10
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Duan W, Yu Z, Cui W, Zhang Z, Zhang W, Tian Y. Bio-inspired switchable soft adhesion for the boost of adhesive surfaces and robotics applications: A brief review. Adv Colloid Interface Sci 2023; 313:102862. [PMID: 36848868 DOI: 10.1016/j.cis.2023.102862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/10/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023]
Abstract
In nature, millions of creatures, such as geckos, tree frogs, octopuses, etc., have evolved fantastic switchable adhesion capabilities to climb swiftly on vertical even inverted surfaces or hunt for prey easily, adapting to harsh and unpredictable environments. Notably, these fascinating adhesive behaviors depend on interfacial forces (friction, van der Waals force, capillary force, vacuum suction, etc.), which primarily originate from the interactions between the soft micro/nanostructures evolved in the natural creatures and objects. Over the past few decades, these biological switchable adhesives have inspired scientists to explore and engineer desirable artificial adhesives. In this review, we summarized the state-of-the-art research on the ultra-fast adhesive motion of three types of biological organisms (gecko, tree frog, and octopus). Firstly, the basic adhesion principles in the three representative organisms, including micro/nanostructures, interfacial forces, and fundamental adhesion models, are reviewed. Then, we discussed the adhesion mechanisms of the prominent organisms from the perspective of soft contacts between micro/nanostructures and the substrates. Later, the mechanics-guided design principles of artificial adhesive surfaces, as well as the smart adhesion strategies, are summarized. The applications of these bio-inspired switchable adhesives are demonstrated, including wearable electronic devices, soft grippers, and climbing robots. The challenges and opportunities in this fast-growing field are also discussed.
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Affiliation(s)
- Weiwang Duan
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Zhilin Yu
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Wenhui Cui
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Zengxin Zhang
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
| | - Wenling Zhang
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Yu Tian
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
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11
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Thomas J, Gorb SN, Büscher TH. Influence of surface free energy of the substrate and flooded water on the attachment performance of stick insects (Phasmatodea) with different adhesive surface microstructures. J Exp Biol 2023; 226:286279. [PMID: 36606728 DOI: 10.1242/jeb.244295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 12/28/2022] [Indexed: 01/07/2023]
Abstract
Stick and leaf insects (Phasmatodea) are exclusively herbivores. As they settle in a broad range of habitats, they need to attach to and walk on a wide variety of plant substrates, which can vary in their surface free energy (SFE). The adhesive microstructures (AMs) on the euplantulae of phasmids are assumed to be adapted to such substrate properties. Moreover, the natural substrates can often be covered with water as a result of high relative humidity or rain. Although considerable experimental research has been carried out on different aspects of stick insect attachment, the adaptations to cope with the influence of flooded water on attachment performance remain unclear. To elucidate the role of AMs in this context, we here measured attachment forces in three species of stick insects with different AMs. The results show that attachment forces of the three species studied were influenced by the SFE and the presence of water: they all showed higher pull-off (vertical) and traction (horizontal) forces on dry surfaces, compared with when the surfaces were covered with a water film. However, the extent to which the surface properties influenced attachment differed depending on the species and its AMs. All three species showed approximately the same attachment performance on dry surfaces with different surface free energy but maintained attachment underwater to different extents.
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Affiliation(s)
- Julian Thomas
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Thies H Büscher
- Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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12
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Hwang GW, Lee HJ, Kim DW, Yang T, Pang C. Soft Microdenticles on Artificial Octopus Sucker Enable Extraordinary Adaptability and Wet Adhesion on Diverse Nonflat Surfaces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2202978. [PMID: 35975453 PMCID: PMC9631055 DOI: 10.1002/advs.202202978] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/24/2022] [Indexed: 06/15/2023]
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.
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Affiliation(s)
- Gui Won Hwang
- School of Chemical EngineeringSungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
| | - Heon Joon Lee
- School of Chemical EngineeringSungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
| | - Da Wan Kim
- School of Chemical EngineeringSungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
- School of Electronic and Electrical EngineeringSungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
| | - Tae‐Heon Yang
- Department of Electronic EngineeringKorea National University of TransportationChungju‐siChungbuk27469Republic of Korea
| | - Changhyun Pang
- School of Chemical EngineeringSungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
- Samsung Advanced Institute for Health Sciences and Technology (SAIHST)Sungkyunkwan University (SKKU)2066 Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
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13
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Bergmann JB, Moatsou D, Steiner U, Wilts BD. Bio-inspired materials to control and minimise insect attachment. BIOINSPIRATION & BIOMIMETICS 2022; 17:051001. [PMID: 36099911 DOI: 10.1088/1748-3190/ac91b9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 09/13/2022] [Indexed: 06/15/2023]
Abstract
More than three quarters of all animal species on Earth are insects, successfully inhabiting most ecosystems on the planet. Due to their opulence, insects provide the backbone of many biological processes, but also inflict adverse impacts on agricultural and stored products, buildings and human health. To countermeasure insect pests, the interactions of these animals with their surroundings have to be fully understood. This review focuses on the various forms of insect attachment, natural surfaces that have evolved to counter insect adhesion, and particularly features recently developed synthetic bio-inspired solutions. These bio-inspired solutions often enhance the variety of applicable mechanisms observed in nature and open paths for improved technological solutions that are needed in a changing global society.
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Affiliation(s)
- Johannes B Bergmann
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Dafni Moatsou
- Institute of Organic Chemistry, Karlsruhe Institute for Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Ullrich Steiner
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Bodo D Wilts
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
- Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Str. 2a, 5020 Salzburg, Austria
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14
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Takahashi H. MEMS-Based Micro Sensors for Measuring the Tiny Forces Acting on Insects. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22208018. [PMID: 36298366 PMCID: PMC9609827 DOI: 10.3390/s22208018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/14/2022] [Accepted: 10/18/2022] [Indexed: 06/01/2023]
Abstract
Small insects perform agile locomotion, such as running, jumping, and flying. Recently, many robots, inspired by such insect performance, have been developed and are expected to be smaller and more maneuverable than conventional robots. For the development of insect-inspired robots, understanding the mechanical dynamics of the target insect is important. However, evaluating the dynamics via conventional commercialized force sensors is difficult because the exerted force and insect itself are tiny in strength and size. Here, we review force sensor devices, especially fabricated for measuring the tiny forces acting on insects during locomotion. As the force sensor, micro-force plates for measuring the ground reaction force and micro-force probes for measuring the flying force have mainly been developed. In addition, many such sensors have been fabricated via a microelectromechanical system (MEMS) process, due to the process precision and high sensitivity. In this review, we focus on the sensing principle, design guide, fabrication process, and measurement method of each sensor, as well as the technical challenges in each method. Finally, the common process flow of the development of specialized MEMS sensors is briefly discussed.
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Affiliation(s)
- Hidetoshi Takahashi
- Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan
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15
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Burack J, Gorb SN, Büscher TH. Attachment Performance of Stick Insects (Phasmatodea) on Plant Leaves with Different Surface Characteristics. INSECTS 2022; 13:952. [PMID: 36292904 PMCID: PMC9604322 DOI: 10.3390/insects13100952] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 10/13/2022] [Accepted: 10/16/2022] [Indexed: 05/25/2023]
Abstract
Herbivorous insects and plants exemplify a longstanding antagonistic coevolution, resulting in the development of a variety of adaptations on both sides. Some plant surfaces evolved features that negatively influence the performance of the attachment systems of insects, which adapted accordingly as a response. Stick insects (Phasmatodea) have a well-adapted attachment system with paired claws, pretarsal arolium and tarsal euplantulae. We measured the attachment ability of Medauroidea extradentata with smooth surface on the euplantulae and Sungaya inexpectata with nubby microstructures of the euplantulae on different plant substrates, and their pull-off and traction forces were determined. These species represent the two most common euplantulae microstructures, which are also the main difference between their respective attachment systems. The measurements were performed on selected plant leaves with different properties (smooth, trichome-covered, hydrophilic and covered with crystalline waxes) representing different types among the high diversity of plant surfaces. Wax-crystal-covered substrates with fine roughness revealed the lowest, whereas strongly structured substrates showed the highest attachment ability of the Phasmatodea species studied. Removal of the claws caused lower attachment due to loss of mechanical interlocking. Interestingly, the two species showed significant differences without claws on wax-crystal-covered leaves, where the individuals with nubby euplantulae revealed stronger attachment. Long-lasting effects of the leaves on the attachment ability were briefly investigated, but not confirmed.
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Affiliation(s)
| | | | - Thies H. Büscher
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, 24118 Kiel, Germany
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16
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van den Boogaart LM, Langowski JKA, Amador GJ. Studying Stickiness: Methods, Trade-Offs, and Perspectives in Measuring Reversible Biological Adhesion and Friction. Biomimetics (Basel) 2022; 7:biomimetics7030134. [PMID: 36134938 PMCID: PMC9496521 DOI: 10.3390/biomimetics7030134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/09/2022] [Accepted: 09/11/2022] [Indexed: 11/16/2022] Open
Abstract
Controlled, reversible attachment is widely spread throughout the animal kingdom: from ticks to tree frogs, whose weights span from 2 mg to 200 g, and from geckos to mosquitoes, who stick under vastly different situations, such as quickly climbing trees and stealthily landing on human hosts. A fascinating and complex interplay of adhesive and frictional forces forms the foundation of attachment of these highly diverse systems to various substrates. In this review, we present an overview of the techniques used to quantify the adhesion and friction of terrestrial animals, with the aim of informing future studies on the fundamentals of bioadhesion, and motivating the development and adoption of new or alternative measurement techniques. We classify existing methods with respect to the forces they measure, including magnitude and source, i.e., generated by the whole body, single limbs, or by sub-structures. Additionally, we compare their versatility, specifically what parameters can be measured, controlled, and varied. This approach reveals critical trade-offs of bioadhesion measurement techniques. Beyond stimulating future studies on evolutionary and physicochemical aspects of bioadhesion, understanding the fundamentals of biological attachment is key to the development of biomimetic technologies, from soft robotic grippers to gentle surgical tools.
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Affiliation(s)
- Luc M. van den Boogaart
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, 6708 WD Wageningen, The Netherlands
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
| | - Julian K. A. Langowski
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, 6708 WD Wageningen, The Netherlands
- Correspondence: (J.K.A.L.); (G.J.A.)
| | - Guillermo J. Amador
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, 6708 WD Wageningen, The Netherlands
- Correspondence: (J.K.A.L.); (G.J.A.)
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17
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Baumgart L, Wittke M, Morsbach S, Abou B, Menzel F. Why do ants differ in acclimatory ability? Biophysical mechanisms behind cuticular hydrocarbon acclimation across species. J Exp Biol 2022; 225:275883. [PMID: 35775442 DOI: 10.1242/jeb.243847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 06/27/2022] [Indexed: 11/20/2022]
Abstract
Maintaining water balance is vital for terrestrial organisms. Insects protect themselves against desiccation via cuticular hydrocarbons (CHCs). CHC layers are complex mixtures of solid and liquid hydrocarbons, with a surprisingly diverse composition across species. This variation may translate to differential phase behaviour, and hence varying waterproofing capacity. This is especially relevant when temperatures change, which requires acclimatory CHC changes to maintain waterproofing. Nevertheless, the physical consequences of CHC variation are still little understood. We studied acclimatory responses and their consequences for CHC composition, phase behaviour, and drought survival in three congeneric ant species. Colony fragments were kept under cool, warm, and fluctuating temperature regimes. Lasius niger and platythorax, both of which are rich in methyl-branched alkanes, showed largely predictable acclimatory changes of the CHC profile. In both species, warm acclimation increased drought resistance. Warm acclimation increased the proportion of solid compounds in L. niger but not in L. platythorax. In both species, the CHC layer formed a liquid matrix of constantly low viscosity, which contained highly viscous and solid parts. This phase heterogeneity may be adaptive, increasing robustness to temperature fluctuations. In L. brunneus, which is rich in unsaturated hydrocarbons, acclimatory CHC changes were less predictable, and warm acclimation did not enhance drought survival. The CHC layer was more homogenous, but matrix viscosity changed with acclimation. We showed that ant species use different physical mechanisms to enhance waterproofing during acclimation. Hence, the ability to acclimate, and thus climatic niche breadth, may strongly depend on species-specific CHC profile.
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Affiliation(s)
- Lucas Baumgart
- Institute of Organismic and Molecular Evolution (iomE), Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany.,Institute of Biology II, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany.,Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
| | - Marti Wittke
- Institute of Organismic and Molecular Evolution (iomE), Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Svenja Morsbach
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Bérengère Abou
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
| | - Florian Menzel
- Institute of Organismic and Molecular Evolution (iomE), Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
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18
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Abstract
Bio-inspired surfaces enabling wet adhesion management are of significant interest for applications in the field of biomedicine, as components of bionic robots and as wearable devices. In the course of biological evolution, many organisms have evolved wet adhesive surfaces with strong attachment ability. Insects enhance their adhesion on contact substrates using secreted adhesive liquids. Here we discuss concepts of bio-inspired wet adhesion. First, remaining challenges associated with the understanding and the design of biological and artificial wet adhesive systems as well as strategies to supply adhesive liquids to their contact surfaces are reviewed. Then, future directions to construct wet adhesive surfaces with liquids are discussed in detail. Finally, a model of wet adhesion management with liquids is suggested, which might help the design of next-generation bio-inspired wet adhesive surfaces.
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Affiliation(s)
- Yupeng Chen
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P.R. China
| | - Zhongpeng Zhu
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P.R. China
| | - Martin Steinhart
- Institut für Chemie neuer Materialien and CellNanOs, Universität Osnabrück, Barbarastr. 7, 49069 Osnabrück, Germany
| | - Stanislav N. Gorb
- Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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19
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Butler MD, Vella D. Liquid bridge splitting enhances normal capillary adhesion and resistance to shear on rough surfaces. J Colloid Interface Sci 2021; 607:514-529. [PMID: 34509122 DOI: 10.1016/j.jcis.2021.08.133] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/20/2021] [Accepted: 08/21/2021] [Indexed: 12/14/2022]
Abstract
HYPOTHESIS 'Bridge splitting' is considered in the case of capillary adhesion: a fixed total volume of liquid is split into multiple capillary bridges. Previous studies have shown that bridge splitting only enhances the capillary-induced adhesion force between two planar surfaces in specific circumstances. We hypothesise that bridge splitting significantly enhances the total adhesion force between rough surfaces, since mobile wetting bridges can naturally migrate to narrower gaps. This migration of capillary bridges should also provide a resistance to shear. NUMERICAL EXPERIMENTS We theoretically consider an idealized system of many liquid bridges confined between two solid surfaces. By numerically calculating the shape of a single bridge, the total adhesion force is found as the number of bridges and roughness are varied. The resistance to shear is also calculated in the limit of strong surface tension or small shears. FINDINGS Bridge splitting on a rough surface significantly enhances the adhesion force, with an enhancement that increases with the amplitude of the roughness; maximising over the number of bridges can increase the total adhesion force by an order of magnitude. Resistance to shear is shown to increase linearly with the translation velocity, and the behaviour of many such shearing bridges is quantified.
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Affiliation(s)
- Matthew D Butler
- Mathematical Institute, University of Oxford, Woodstock Rd, Oxford OX2 6GG, United Kingdom; School of Mathematics, University of Birmingham, Edgbaston B15 2TT, United Kingdom.
| | - Dominic Vella
- Mathematical Institute, University of Oxford, Woodstock Rd, Oxford OX2 6GG, United Kingdom.
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20
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Colonial chemical signature of social wasps and their nesting substrates. CHEMOECOLOGY 2021. [DOI: 10.1007/s00049-021-00361-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Liang J, Wu Y, Yim JK, Chen H, Miao Z, Liu H, Liu Y, Liu Y, Wang D, Qiu W, Shao Z, Zhang M, Wang X, Zhong J, Lin L. Electrostatic footpads enable agile insect-scale soft robots with trajectory control. Sci Robot 2021; 6:6/55/eabe7906. [PMID: 34193563 DOI: 10.1126/scirobotics.abe7906] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 06/02/2021] [Indexed: 12/11/2022]
Abstract
Agility and trajectory control are two desirable features for robotics, but they become very challenging for soft robots without rigid structures to support rapid manipulations. Here, a curved piezoelectric thin film driven at its structural resonant frequency is used as the main body of an insect-scale soft robot for its fast translational movements, and two electrostatic footpads are used for its swift rotational motions. These two schemes are simultaneously executed during operations through a simple two-wire connection arrangement. A high relative centripetal acceleration of 28 body length per square second compared with existing robots is realized on a 65-milligram tethered prototype, which is better than those of common insects, including the cockroach. The trajectory manipulation demonstration is accomplished by navigating the robot to pass through a 120-centimeter-long track in a maze within 5.6 seconds. One potential application is presented by carrying a 180-milligram on-board sensor to record a gas concentration route map and to identify the location of the leakage source. The radically simplified analog motion adjustment technique enables the scale-up construction of a 240-milligram untethered robot. Equipped with a payload of 1660 milligrams to include the control circuit, a battery, and photoresistors, the untethered prototype can follow a designated, 27.9-centimeter-long "S"-shaped path in 36.9 seconds. These results validate key performance attributes in achieving both high mobility and agility to emulate living agile insects for the advancements of soft robots.
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Affiliation(s)
- Jiaming Liang
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.,Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.,Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Yichuan Wu
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Justin K Yim
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15289, USA
| | - Huimin Chen
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Zicong Miao
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Hanxiao Liu
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.,Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Ying Liu
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China
| | - Yixin Liu
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Dongkai Wang
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.,Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.,Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Wenying Qiu
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.,Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA.,Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Zhichun Shao
- Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Min Zhang
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
| | - Xiaohao Wang
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.,Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Junwen Zhong
- Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA. .,Department of Electromechanical Engineering, Centre for Artificial Intelligence and Robotics, University of Macau, Macao 999078, China
| | - Liwei Lin
- Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China. .,Berkeley Sensor and Actuator Center, Department of Mechanical Engineering, University of California at Berkeley, Berkeley, CA 94720, USA
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22
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Surface chemistry of the ladybird beetle adhesive foot fluid across various substrates. Biointerphases 2021; 16:031004. [PMID: 34241230 DOI: 10.1116/6.0001006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nature has coevolved highly adaptive and reliable bioadhesives across a multitude of animal species. Much attention has been paid in recent years to selectively mimic these adhesives for the improvement of a variety of technologies. However, very few of the chemical mechanisms that drive these natural adhesives are well understood. Many insects combine hairy feet with a secreted adhesive fluid, allowing for adhesion to considerably rough and slippery surfaces. Insect adhesive fluids have evolved highly specific compositions which are consistent across most surfaces and optimize both foot adhesion and release in natural environments. For example, beetles are thought to have adhesive fluids made up of a complex molecular mixture containing both hydrophobic and hydrophilic parts. We hypothesize that this causes the adhesive interface to be dynamic, with molecules in the fluid selectively organizing and ordering at surfaces with complimentary hydrophobicity to maximize adhesion. In this study, we examine the adhesive fluid of a seven-spotted ladybird beetle with a surface-sensitive analytical technique, sum frequency generation spectroscopy, as the fluid interacts with three substrates of varied wettabilities. The resulting spectra present no evidence of unique molecular environments between hydrophilic and hydrophobic surfaces but exhibit significant differences in the ordering of hydrocarbons. This change in surface interactions across different substrates correlates well with traction forces measured from beetles interacting with substrates of increasing hydrophobicities. We conclude that insect adhesion is dependent upon a dynamic molecular-interfacial response to an environmental surface.
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23
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Singla S, Jain D, Zoltowski CM, Voleti S, Stark AY, Niewiarowski PH, Dhinojwala A. Direct evidence of acid-base interactions in gecko adhesion. SCIENCE ADVANCES 2021; 7:7/21/eabd9410. [PMID: 34138740 PMCID: PMC8133704 DOI: 10.1126/sciadv.abd9410] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 03/29/2021] [Indexed: 05/06/2023]
Abstract
While it is generally accepted that van der Waals (vdW) forces govern gecko adhesion, several studies indicate contributions from non-vdW forces and highlight the importance of understanding the adhesive contact interface. Previous work hypothesized that the surface of gecko setae is hydrophobic, with nonpolar lipid tails exposed on the surface. However, direct experimental evidence supporting this hypothesis and its implications on the adhesion mechanism is lacking. Here, we investigate the sapphire-setae contact interface using interface-sensitive spectroscopy and provide direct evidence of the involvement of acid-base interactions between polar lipid headgroups exposed on the setal surface and sapphire. During detachment, a layer of unbound lipids is left as a footprint due to cohesive failure within the lipid layer, which, in turn, reduces wear to setae during high stress sliding. The absence of this lipid layer enhances adhesion, despite a small setal-substrate contact area. Our results show that gecko adhesion is not exclusively a vdW-based, residue-free system.
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Affiliation(s)
- Saranshu Singla
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Dharamdeep Jain
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Chelsea M Zoltowski
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Sriharsha Voleti
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Alyssa Y Stark
- Integrated Bioscience Program, University of Akron, Akron, OH 44325-3908, USA
- Department of Biology, Villanova University, Villanova, PA 19085, USA
| | | | - Ali Dhinojwala
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA.
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24
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Wang Y, Chen G, Zhang H, Zhao C, Sun L, Zhao Y. Emerging Functional Biomaterials as Medical Patches. ACS NANO 2021; 15:5977-6007. [PMID: 33856205 DOI: 10.1021/acsnano.0c10724] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Medical patches have been widely explored and applied in various medical fields, especially in wound healing, tissue engineering, and other biomedical areas. Benefiting from emerging biomaterials and advanced manufacturing technologies, great achievements have been made on medical patches to evolve them into a multifunctional medical device for diverse health-care purposes, thus attracting extensive attention and research interest. Here, we provide up-to-date research concerning emerging functional biomaterials as medical patches. An overview of the various approaches to construct patches with micro- and nanoarchitecture is presented and summarized. We then focus on the applications, especially the biomedical applications, of the medical patches, including wound healing, drug delivery, and real-time health monitoring. The challenges and prospects for the future development of the medical patches are also discussed.
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Affiliation(s)
- Yu Wang
- Department of Rheumatology and Immunology, Institute of Translational Medicine, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 210008 Nanjing, China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Guopu Chen
- Department of Rheumatology and Immunology, Institute of Translational Medicine, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 210008 Nanjing, China
| | - Han Zhang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Cheng Zhao
- Department of Rheumatology and Immunology, Institute of Translational Medicine, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 210008 Nanjing, China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Lingyun Sun
- Department of Rheumatology and Immunology, Institute of Translational Medicine, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 210008 Nanjing, China
| | - Yuanjin Zhao
- Department of Rheumatology and Immunology, Institute of Translational Medicine, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 210008 Nanjing, China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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25
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Evidence for intermolecular forces involved in ladybird beetle tarsal setae adhesion. Sci Rep 2021; 11:7729. [PMID: 33833354 PMCID: PMC8032735 DOI: 10.1038/s41598-021-87383-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 03/26/2021] [Indexed: 11/23/2022] Open
Abstract
Why can beetles such as the ladybird beetle Coccinella septempunctata walk vertically or upside-down on a smooth glass plane? Intermolecular and/or capillary forces mediated by a secretion fluid on the hairy footpads have commonly been considered the predominant adhesion mechanism. However, the main contribution of physical phenomena to the resulting overall adhesive force has yet to be experimentally proved, because it is difficult to quantitatively analyse the pad secretion which directly affects the adhesion mechanism. We observed beetle secretion fluid by using inverted optical microscopy and cryo-scanning electron microscopy, which showed the fluid secretion layer and revealed that the contact fluid layer between the footpad and substrate was less than 10–20 nm thick, thus indicating the possibility of contribution of intermolecular forces. If intermolecular force is the main physical phenomenon of adhesion, the force will be proportional to the work of adhesion, which can be described by the sum of the square roots of dispersive and polar parts of surface free energy. We measured adhesion forces of ladybird beetle footpads to flat, smooth substrates with known surface free energies. The adhesive force was proportional to the square-root of the dispersive component of the substrate surface free energy and was not affected by the polar component. Therefore, intermolecular forces are the main adhesive component of the overall adhesion force of the ladybird beetle. The footpads adhere more strongly to surfaces with higher dispersive components, such as wax-covered plant leaves found in the natural habitat of ladybird beetles. Based on the present findings, we assume ladybird beetles have developed this improved performance as an adaptation to the variety of plant species in its habitat.
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26
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Labonte D, Robinson A, Bauer U, Federle W. Disentangling the role of surface topography and intrinsic wettability in the prey capture mechanism of Nepenthes pitcher plants. Acta Biomater 2021; 119:225-233. [PMID: 33189952 DOI: 10.1016/j.actbio.2020.11.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/15/2020] [Accepted: 11/03/2020] [Indexed: 11/27/2022]
Abstract
Nepenthes pitcher plants capture prey with leaves specialised as pitfall traps. Insects are trapped when they 'aquaplane' on the pitcher rim (peristome), a surface structured with macroscopic and microscopic radial ridges. What is the functional significance of this hierarchical surface topography? Here, we use insect pad friction measurements, photolithography, wetting experiments and physical modelling to demonstrate that the ridges enhance the trap's efficacy by satisfying two functional demands on prey capture: Macroscopic ridges restrict lateral but enhance radial spreading of water, thereby creating continuous slippery tracks which facilitate prey capture when little water is present. Microscopic ridges, in turn, ensure that the water film between insect pad and peristome remains stable, causing insects to aquaplane. In combination, the hierarchical ridge structure hence renders the peristome wettable, and water films continuous, so avoiding the need for a strongly hydrophilic surface chemistry, which would compromise resistance to desiccation and attract detrimental contamination.
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27
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Shima D, Gan JH, Umezu S, Sato H. Smooth and slipless walking mechanism inspired by the open-close cycle of a beetle claw. BIOINSPIRATION & BIOMIMETICS 2020; 16:016011. [PMID: 33263306 DOI: 10.1088/1748-3190/abb0ca] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This study investigated the function of the beetle's claw for its smooth and slipless walking and designed an artificial claw open-close cycle mechanism to mimic the beetle's walking. First, the effects of claw opening and closing on beetles' ability to attach to surfaces were examined. A beetle does not have an attachment pad, and only its claws work to grip the ground; its claw opens and closes and attaches with two sharp hooks. With their claws, beetles can smoothly walk, neither slipping on nor having their claws stuck in the surface. How do they perform smooth walking with sharp claws? In this study, we observed that beetles close their claws when they raise and swung their legs forward, while they open their claws when they lowered their legs to the ground. We then conducted non-destructive tests: their claws were forced open or closed. There was a significant difference in the trajectories of forced-closed claws compared to intact claws and forced-open claws. When their claws were forced-closed, this caused slippage in walking. On the other hand, when a claw was forced-open and its rotation was also inhibited, the claw stuck heavily in the surface, and the beetle could not walk. Based on these findings, we designed an artificial claw to open and close in the same cyclic manner as in the case of natural beetles. The performance of the artificial claw was consistent with the conclusions drawn from natural beetles: the locomotive robot with the artificial claw smoothly moved without slippage. Through these observations, non-destructive tests and performance of the bio-inspired artificial claws, this study confirmed the function of the open-close cycle of beetle claws and demonstrated and successfully adopted it for a locomotive robot.
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Affiliation(s)
- Daiki Shima
- School of Department of Modern Mechanical Engineering, Waseda University, Japan
| | - Jia Hui Gan
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
| | - Shinjiro Umezu
- School of Department of Modern Mechanical Engineering, Waseda University, Japan
| | - Hirotaka Sato
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
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28
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Boudinot BE, Beutel RG, Gorb SN, Polilov AA. Functional diversity of attachment and grooming leg structures is retained in all but the smallest insects. J Zool (1987) 2020. [DOI: 10.1111/jzo.12840] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- B. E. Boudinot
- Department of Entomology & Nematology University of California Davis CA USA
| | - R. G. Beutel
- Institut für Zoologie und Evolutionsforschung Friedrich‐Schiller‐Universität Jena Germany
- Economo Group Okinawa Institute of Science and Technology (OIST) Tancha Japan
| | - S. N. Gorb
- Department Functional Morphology and Biomechanics Zoological Institute of the University of Kiel Kiel Germany
| | - A. A. Polilov
- Department of Entomology Biological faculty Lomonosov Moscow State University Moscow Russia
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29
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O'Donnell MK, Deban SM. The Effects of Roughness and Wetness on Salamander Cling Performance. Integr Comp Biol 2020; 60:840-851. [PMID: 32687157 DOI: 10.1093/icb/icaa110] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Animals clinging to natural surfaces have to generate attachment across a range of surface roughnesses in both dry and wet conditions. Plethodontid salamanders can be aquatic, semi-aquatic, terrestrial, arboreal, troglodytic, saxicolous, and fossorial and therefore may need to climb on and over rocks, tree trunks, plant leaves, and stems, as well as move through soil and water. Sixteen species of salamanders were tested to determine the effects of substrate roughness and wetness on maximum cling angle. Substrate roughness had a significant effect on maximum cling angle, an effect that varied among species. Substrates of intermediate roughness (asperity size 100-350 µm) resulted in the poorest attachment performance for all species. Small species performed best on smooth substrates, while large species showed significant improvement on the roughest substrates (asperity size 1000-4000 µm), possibly switching from mucus adhesion on a smooth substrate to an interlocking attachment on rough substrates. Water, in the form of a misted substrate coating and a flowing stream, decreased cling performance in salamanders on smooth substrates. However, small salamanders significantly increased maximum cling angle on wetted substrates of intermediate roughness, compared with the dry condition. Study of cling performance and its relationship to surface properties may cast light onto how this group of salamanders has radiated into the most speciose family of salamanders that occupies diverse habitats across an enormous geographical range.
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Affiliation(s)
- Mary Kate O'Donnell
- Department of Ecology and Evolutionary Biology, Brown University, 171 Meeting Street, GB 204, Providence, RI 02912, USA; Department of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, SCA 110, Tampa, FL 33620, USA
| | - Stephen M Deban
- Department of Ecology and Evolutionary Biology, Brown University, 171 Meeting Street, GB 204, Providence, RI 02912, USA; Department of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, SCA 110, Tampa, FL 33620, USA
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30
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Beutel RG, Richter A, Keller RA, Hita Garcia F, Matsumura Y, Economo EP, Gorb SN. Distal leg structures of the Aculeata (Hymenoptera): A comparative evolutionary study of Sceliphron (Sphecidae) and Formica (Formicidae). J Morphol 2020; 281:737-753. [PMID: 32364646 DOI: 10.1002/jmor.21133] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/13/2020] [Accepted: 04/15/2020] [Indexed: 11/08/2022]
Abstract
The distal parts of the legs of Sceliphron caementarium (Sphecidae) and Formica rufa (Formicidae) are documented and discussed with respect to phylogenetic and functional aspects. The prolegs of Hymenoptera offer an array of evolutionary novelties, mainly linked with two functional syndromes, walking efficiently on different substrates and cleaning the body surface. The protibial-probasitarsomeral cleaning device is almost always well-developed. A complex evolutionary innovation is a triple set of tarsal and pretarsal attachment devices, including tarsal plantulae, probasitarsomeral spatulate setae, and an arolium with an internal spring-like arcus, a dorsal manubrium, and a ventral planta. The probasitarsal adhesive sole and a complex arolium are almost always preserved, whereas the plantulae are often missing. Sceliphron has retained most hymenopteran ground plan features of the legs, and also Formica, even though the adhesive apparatus of Formicidae shows some modifications, likely linked to ground-oriented habits of most ants. Plantulae are always absent in extant ants, and the arolium is often reduced in size, and sometimes vestigial. The arolium contains resilin in both examined species. Additionally, resilin enriched regions are also present in the antenna cleaners of both species, although they differ in which of the involved structures is more flexible, the calcar in Sceliphron and the basitarsal comb in Formica. Functionally, the hymenopteran distal leg combines (a) interlocking mechanisms (claws, spine-like setae) and (b) adhesion mechanisms (plantulae, arolium). On rough substrate, claws and spine-like setae interlock with asperities and secure a firm grip, whereas the unfolding arolium generates adhesive contact on smooth surfaces. Differences of the folded arolium of Sceliphron and Formica probably correlate with differences in the mechanism of folding/unfolding.
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Affiliation(s)
- Rolf Georg Beutel
- Institut für Zoologie und Evolutionsforschung, Friedrich-Schiller-Universität, Jena, Germany
| | - Adrian Richter
- Institut für Zoologie und Evolutionsforschung, Friedrich-Schiller-Universität, Jena, Germany
| | - Roberto A Keller
- Museu Nacional de Historia Natural e da Ciência and Centre for Ecology, Evolution and Environmental Changes, Universidade de Lisboa, Lisbon, Portugal
| | - Francisco Hita Garcia
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Yoko Matsumura
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel, Germany
| | - Evan P Economo
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel, Germany
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31
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Iazzolino A, Cerkvenik U, Tourtit Y, Ladang A, Compère P, Gilet T. Liquid dispensing in the adhesive hairy pads of dock beetles. J R Soc Interface 2020; 17:20200024. [PMID: 32370693 PMCID: PMC7276548 DOI: 10.1098/rsif.2020.0024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/07/2020] [Indexed: 11/12/2022] Open
Abstract
Many insects can climb on smooth inverted substrates using adhesive hairy pads on their legs. The hair-surface contact is often mediated by minute volumes of liquid, which form capillary bridges in the contact zones and aid in adhesion. The liquid transport to the contact zones is poorly understood. We investigated the dynamics of liquid secretion in the dock beetle Gastrophysa viridula by quantifying the volume of the deposited liquid footprints during simulated walking experiments. The footprint volume increased with pad-surface contact time and was independent of the non-contact time. Furthermore, the footprint volume decreased to zero after reaching a threshold cumulative volume (approx. 30 fl) in successive steps. This suggests a limited reservoir with low liquid influx. We modelled our results as a fluidic resistive system and estimated the hydraulic resistance of a single attachment hair of the order of MPa · s/fl. The liquid secretion in beetle hairy pads is dominated by passive suction of the liquid during the contact phase. The high calculated resistance of the secretion pathway may originate from the nanosized channels in the hair cuticle. Such nanochannels presumably mediate the transport of cuticular lipids, which are chemically similar to the adhesive liquid.
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Affiliation(s)
- Antonio Iazzolino
- Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
| | - Uroš Cerkvenik
- Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
- Functional and Evolutionary Morphology Laboratory, FOCUS, University of Liège, Liège, Belgium
| | - Youness Tourtit
- Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
- Transfers, Interfaces and Processes, Université Libre de Bruxelles, Bruxelles, Belgium
| | - Auxane Ladang
- Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
| | - Philippe Compère
- Functional and Evolutionary Morphology Laboratory, FOCUS, University of Liège, Liège, Belgium
| | - Tristan Gilet
- Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium
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32
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Gorb EV, Lemke W, Gorb SN. Porous substrate affects a subsequent attachment ability of the beetle Harmonia axyridis (Coleoptera, Coccinellidae). J R Soc Interface 2020; 16:20180696. [PMID: 30958175 DOI: 10.1098/rsif.2018.0696] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
According to literature data, porous substrates can cause a reduction of insect attachment ability. We carried out traction experiments with adult ladybird beetles Harmonia axyridis on the smooth solid glass sample and rough porous Al2O3 membrane to prove the primary effect of absorption of the insect pad secretion by porous media, rather than surface roughness, on the attachment force on the porous sample. With each insect individual, a set of five experiments was conducted: (1) on glass; (2) on the porous membrane; (3-5) on glass immediately after the test on the porous surface, then after 30 min and 1 h of recovery time. On the porous substrate, the forces, being similar in females and males, were greatly reduced compared to those measured on glass. A significant difference between the force values obtained in the first (before the test on the porous sample) and second (immediately after the experiment on the porous sample) tests on glass was observed. After 30 min recovery time, beetles completely regained their attachment ability. Females produced significantly lower forces than males in all experiments on glass: the differences are probably caused by the sexual dimorphism in the microstructure of their adhesive pads. The obtained results are of fundamental importance for further application in biomimetics of novel insect-repelling surfaces and in plant protection by using porous materials.
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Affiliation(s)
- Elena V Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel , Germany
| | - Wiebke Lemke
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel , Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University , Am Botanischen Garten 9, 24118 Kiel , Germany
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33
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Büscher TH, Gorb SN. Complementary effect of attachment devices in stick insects (Phasmatodea). ACTA ACUST UNITED AC 2019; 222:jeb.209833. [PMID: 31727762 DOI: 10.1242/jeb.209833] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/06/2019] [Indexed: 11/20/2022]
Abstract
Stick insects are well adapted in their locomotion to various surfaces and topographies of natural substrates. Single pad measurements characterised the pretarsal arolia of these insects as shear-sensitive adhesive pads and the tarsal euplantulae as load-sensitive friction pads. Different attachment microstructures on the euplantulae reveal an adaptation of smooth euplantulae to smooth surfaces and nubby eupantulae to a broader range of surface roughness. However, how different attachment pads and claws work in concert and how strong the contribution of different structures is to the overall attachment performance remains unclear. We therefore assessed combinatory effects in the attachment system of two stick insect species with different types of euplantular microstructures by analysing their usage in various posture situations and the performance on different levels of substrate roughness. For comparison, we provide attachment force data of the whole attachment system. The combination of claws, arolia and euplantulae provides mechanical interlocking on rough surfaces, adhesion and friction on smooth surfaces in different directions, and facilitates attachment on different inclines and on a broad range of surface roughness, with the least performance in the range 0.3-1.0 µm. On smooth surfaces, stick insects use arolia always, but employ euplantulae if the body weight can generate load on them (upright, wall). On structured surfaces, claws enable mechanical interlocking at roughnesses higher than 12 µm. On less-structured surfaces, the attachment strength depends on the use of pads and, corroborating earlier studies, favours smooth pads on smooth surfaces, but nubby euplantulae on micro-rough surfaces.
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Affiliation(s)
- Thies H Büscher
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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34
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Ditsche P, Summers A. Learning from Northern clingfish (Gobiesox maeandricus): bioinspired suction cups attach to rough surfaces. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190204. [PMID: 31495305 PMCID: PMC6745484 DOI: 10.1098/rstb.2019.0204] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2019] [Indexed: 12/26/2022] Open
Abstract
While artificial suction cups only attach well to smooth surfaces, the Northern clingfish can attach to surfaces ranging from nanoscale smooth to rough stone. This ability is highly desirable for technical applications. The morphology of the fish's suction disc and its ability to attach to rough and slimy surfaces have been described before, and here we aim to close gaps in the biomechanical understanding, and transfer the biomechanical principles to technical suction cups. We demonstrate that the margin of the suction disc is the critical feature enabling attachment to rough surfaces. Second, friction measurements show that friction of the disc rim is increased on rough substrates and contributes to high tenacity. Increased friction causes a delay in failure of the suction cup and increases the attachment force. We were able to implement these concepts to develop the first suction cups bioinspired by Northern clingfish. These cups attach with tenacities up to 70 kPa on surfaces as rough as 270 µm grain size. The application of this technology is promising in fields such as surgery, industrial production processes and whale tagging. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.
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Affiliation(s)
- Petra Ditsche
- Friday Harbor Laboratories, University of Washington, 620 University Drive, Friday Harbor, WA 98250, USA
- Department of Biological Science, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, 99508-4614 AK, USA
| | - Adam Summers
- Friday Harbor Laboratories, University of Washington, 620 University Drive, Friday Harbor, WA 98250, USA
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35
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Federle W, Labonte D. Dynamic biological adhesion: mechanisms for controlling attachment during locomotion. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190199. [PMID: 31495309 PMCID: PMC6745483 DOI: 10.1098/rstb.2019.0199] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2019] [Indexed: 01/12/2023] Open
Abstract
The rapid control of surface attachment is a key feature of natural adhesive systems used for locomotion, and a property highly desirable for man-made adhesives. Here, we describe the challenges of adhesion control and the timescales involved across diverse biological attachment systems and different adhesive mechanisms. The most widespread control principle for dynamic surface attachment in climbing animals is that adhesion is 'shear-sensitive' (directional): pulling adhesive pads towards the body results in strong attachment, whereas pushing them away from it leads to easy detachment, providing a rapid mechanical 'switch'. Shear-sensitivity is based on changes of contact area and adhesive strength, which in turn arise from non-adhesive default positions, the mechanics of peeling, pad sliding, and the targeted storage and controlled release of elastic strain energy. The control of adhesion via shear forces is deeply integrated with the climbing animals' anatomy and locomotion, and involves both active neuromuscular control, and rapid passive responses of sophisticated mechanical systems. The resulting dynamic adhesive systems are robust, reliable, versatile and nevertheless remarkably simple. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.
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Affiliation(s)
- Walter Federle
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - David Labonte
- Department of Bioengineering, Imperial College, London, UK
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36
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Labonte D, Struecker MY, Birn-Jeffery AV, Federle W. Shear-sensitive adhesion enables size-independent adhesive performance in stick insects. Proc Biol Sci 2019; 286:20191327. [PMID: 31640508 DOI: 10.1098/rspb.2019.1327] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The ability to climb with adhesive pads conveys significant advantages and is widespread in the animal kingdom. The physics of adhesion predict that attachment is more challenging for large animals, whereas detachment is harder for small animals, due to the difference in surface-to-volume ratios. Here, we use stick insects to show that this problem is solved at both ends of the scale by linking adhesion to the applied shear force. Adhesive forces of individual insect pads, measured with perpendicular pull-offs, increased approximately in proportion to a linear pad dimension across instars. In sharp contrast, whole-body force measurements suggested area scaling of adhesion. This discrepancy is explained by the presence of shear forces during whole-body measurements, as confirmed in experiments with pads sheared prior to detachment. When we applied shear forces proportional to either pad area or body weight, pad adhesion also scaled approximately with area or mass, respectively, providing a mechanism that can compensate for the size-related loss of adhesive performance predicted by isometry. We demonstrate that the adhesion-enhancing effect of shear forces is linked to pad sliding, which increased the maximum adhesive force per area sustainable by the pads. As shear forces in natural conditions are expected to scale with mass, sliding is more frequent and extensive in large animals, thus ensuring that large animals can attach safely, while small animals can still detach their pads effortlessly. Our results therefore help to explain how nature's climbers maintain a dynamic attachment performance across seven orders of magnitude in body weight.
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Affiliation(s)
- David Labonte
- Department of Bioengineering, Imperial College, London, UK
| | | | | | - Walter Federle
- Department of Zoology, University of Cambridge, Cambridge, UK
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37
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Büscher TH, Kryuchkov M, Katanaev VL, Gorb SN. Versatility of Turing patterns potentiates rapid evolution in tarsal attachment microstructures of stick and leaf insects (Phasmatodea). J R Soc Interface 2019; 15:rsif.2018.0281. [PMID: 29925583 DOI: 10.1098/rsif.2018.0281] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 05/30/2018] [Indexed: 11/12/2022] Open
Abstract
In its evolution, the diverse group of stick and leaf insects (Phasmatodea) has undergone a rapid radiation. These insects evolved specialized structures to adhere to different surfaces typical for their specific ecological environments. The cuticle of their tarsal attachment pads (euplantulae) is known to possess a high diversity of attachment microstructures (AMS) which are suggested to reflect ecological specializations of different groups within phasmids. However, the origin of these microstructures and their developmental background remain largely unknown. Here, based on the detailed scanning electron microscopy study of pad surfaces, we present a theoretical approach to mathematically model an outstanding diversity of phasmid AMS using the reaction-diffusion model by Alan Turing. In general, this model explains pattern formation in nature. For the first time, we were able to identify eight principal patterns and simulate the transitions among these. In addition, intermediate transitional patterns were predicted by the model. The ease of transformation suggests a high adaptability of the microstructures that might explain the rapid evolution of pad characters. We additionally discuss the functional morphology of the different microstructures and their assumed advantages in the context of the ecological background of species.
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Affiliation(s)
- Thies H Büscher
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel, Germany
| | - Mikhail Kryuchkov
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Vladimir L Katanaev
- Department of Pharmacology and Toxicology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.,School of Biomedicine, Far Eastern Federal University, Vladivostok, Russia
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel, Germany
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38
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Baik S, Lee HJ, Kim DW, Kim JW, Lee Y, Pang C. Bioinspired Adhesive Architectures: From Skin Patch to Integrated Bioelectronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1803309. [PMID: 30773697 DOI: 10.1002/adma.201803309] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 10/31/2018] [Indexed: 05/21/2023]
Abstract
The attachment phenomena of various hierarchical architectures found in nature have extensively drawn attention for developing highly biocompatible adhesive on skin or wet inner organs without any chemical glue. Structural adhesive systems have become important to address the issues of human-machine interactions by smart outer/inner organ-attachable devices for diagnosis and therapy. Here, advances in designs of biologically inspired adhesive architectures are reviewed in terms of distinct structural properties, attachment mechanisms to biosurfaces by physical interactions, and noteworthy fabrication methods. Recent demonstrations of bioinspired adhesive architectures as adhesive layers for medical applications from skin patches to multifunctional bioelectronics are presented. To conclude, current challenges and prospects on potential applications are also briefly discussed.
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Affiliation(s)
- Sangyul Baik
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Heon Joon Lee
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Da Wan Kim
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Ji Won Kim
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Youngkwan Lee
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Changhyun Pang
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
- SKKU Advanced Institute of Nanotechnology (SAINT), Samsung Advanced Institute for Health Science & Technology (SAIHST), Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
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39
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Crystal growth of magnesium oxide nanocompounds for wetting alteration of carbonate surfaces. CHEMICAL PAPERS 2019. [DOI: 10.1007/s11696-019-00805-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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40
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Stark AY, Davis HR, Harrison WK. Shear adhesive performance of leaf‐cutting ant workers (
Atta cephalotes
). Biotropica 2019. [DOI: 10.1111/btp.12664] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Alyssa Y. Stark
- Department of Biology Villanova University Villanova Pennsylvania
| | - Hayden R. Davis
- Department of Biology Villanova University Villanova Pennsylvania
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41
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Goetzke HH, Pattrick JG, Federle W. Froghoppers jump from smooth plant surfaces by piercing them with sharp spines. Proc Natl Acad Sci U S A 2019; 116:3012-3017. [PMID: 30718417 PMCID: PMC6386693 DOI: 10.1073/pnas.1814183116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Attachment mechanisms used by climbing animals facilitate their interactions with complex 3D environments and have inspired novel types of synthetic adhesives. Here we investigate one of the most dynamic forms of attachment, used by jumping insects living on plants. Froghopper insects can perform explosive jumps with some of the highest accelerations known among animals. As many plant surfaces are smooth, we studied whether Philaenus spumarius froghoppers are able to take off from such substrates. When attempting to jump from smooth glass, the insects' hind legs slipped, resulting in weak, uncontrolled jumps with a rapid forward spin. By contrast, on smooth ivy leaves and smooth epoxy surfaces, Philaenus froghoppers performed strong jumps without any slipping. We discovered that the insects produced traction during the acceleration phase by piercing these substrates with sharp spines of their tibia and tarsus. High-speed microscopy recordings of hind legs during the acceleration phase of jumps revealed that the spine tips indented and plastically deformed the substrate. On ivy leaves, the spines of jumping froghoppers perforated the cuticle and epidermal cell walls, and wounds could be visualized after the jumps by methylene blue staining and scanning electron microscopy. Improving attachment performance by indenting or piercing plant surfaces with sharp spines may represent a widespread but previously unrecognized strategy utilized by plant-living insects. This attachment mechanism may also provide inspiration for the design of robotic grippers.
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Affiliation(s)
- Hanns Hagen Goetzke
- Department of Zoology, University of Cambridge, CB2 3EJ Cambridge, United Kingdom
| | - Jonathan G Pattrick
- Department of Zoology, University of Cambridge, CB2 3EJ Cambridge, United Kingdom
- Department of Plant Sciences, University of Cambridge, CB2 3EA Cambridge, United Kingdom
| | - Walter Federle
- Department of Zoology, University of Cambridge, CB2 3EJ Cambridge, United Kingdom;
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Menzel F, Morsbach S, Martens JH, Räder P, Hadjaje S, Poizat M, Abou B. Communication vs. waterproofing: the physics of insect cuticular hydrocarbons. J Exp Biol 2019; 222:jeb.210807. [DOI: 10.1242/jeb.210807] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/28/2019] [Indexed: 12/26/2022]
Abstract
Understanding the evolution of complex traits is among the major challenges in biology. One such trait is the cuticular hydrocarbon (CHC) layer in insects. It protects against desiccation and provides communication signals, especially in social insects. CHC composition is highly diverse within and across species. To understand the adaptive value of this chemical diversity, we must understand how it affects biological functionality. So far, CHCs received ample research attention, but their physical properties were little studied. We argue that these properties determine their biological functionality, and are vital to understand how CHC composition affects their adaptive value. We investigated melting behaviour and viscosity of CHCs from eleven ant species using differential scanning calorimetry and a novel microrheological technique.
Cuticular hydrocarbons began melting below -45°C, and often were entirely liquid only above 30°C. Thus, they formed a solid-liquid mixture at ambient conditions, which contrasts to previous assumptions of entirely solid layers in many species. This may be adaptive since only biphasic CHC layers ensure uniform coating of the insect body, which is necessary for waterproofing. CHC viscosity was mostly between 0.1 and 0.2 Pa.s, thus similar to motor oils. Surprisingly, chemically different CHC profiles had similar viscosities, suggesting that a certain viscosity level is adaptive and ensures that communication signals can be perceived.
With this study, we draw attention to the importance of studying the physics of CHC layers. Only by understanding how chemical and physical mechanisms enable CHC functionality can we understand the causes and consequences of CHC diversification.
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Affiliation(s)
- Florian Menzel
- Institute of Organismic and Molecular Evolution, Faculty of Biology, University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
| | - Svenja Morsbach
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jiska H. Martens
- Institute of Organismic and Molecular Evolution, Faculty of Biology, University of Mainz, Hanns-Dieter-Hüsch-Weg 15, 55128 Mainz, Germany
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
| | - Petra Räder
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Simon Hadjaje
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
| | - Marine Poizat
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
| | - Bérengère Abou
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université de Paris, 75205 Paris Cedex 13, France
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Gilet T, Heepe L, Lambert P, Compère P, Gorb SN. Liquid secretion and setal compliance: the beetle's winning combination for a robust and reversible adhesion. CURRENT OPINION IN INSECT SCIENCE 2018; 30:19-25. [PMID: 30553481 DOI: 10.1016/j.cois.2018.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/12/2018] [Accepted: 08/18/2018] [Indexed: 06/09/2023]
Abstract
This paper is a brief review and discussion of the recent literature on the hairy adhesive pads of beetles, with the focus on two features of these pads, firstly, compliant setal tips and secondly, a liquid secretion, that together guarantee robust cycles of attachment/detachment on smooth and rough substrates. The compliance is required to ensure sufficient contact between the setal tips and the substrate with a minimum of elastically stored energy at the contact interface. The secretion fills potential gaps between both surfaces, generates capillary adhesive forces, and enhances self-cleaning of these microstructures. Furthermore, the secretion might prevent setal dehydration and subsequently maintain setal tip compliancy. The paper also pinpoints a series of open questions on the physical mechanisms at play to passively regulate the contact forces developed by these hairy pads during locomotion.
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Affiliation(s)
- Tristan Gilet
- Microfluidics Lab, Aerospace and Mechanical Engineering, University of Liège, B-4000 Liège, Belgium.
| | - Lars Heepe
- Functional Morphology and Biomechanics, Kiel University, D-24118 Kiel, Germany
| | - Pierre Lambert
- TIPs, CP 165/67, Université Libre de Bruxelles, B-1000 Brussels, Belgium
| | - Philippe Compère
- Laboratoire de Morphologie Fonctionnelle et Evolutive, FOCUS, University of Liège, B-4000 Liège, Belgium
| | - Stanislav N Gorb
- Functional Morphology and Biomechanics, Kiel University, D-24118 Kiel, Germany
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Stark AY, Yanoviak SP. Adhesion and running speed of a tropical arboreal ant ( Cephalotes atratus) on wet substrates. ROYAL SOCIETY OPEN SCIENCE 2018; 5:181540. [PMID: 30564427 PMCID: PMC6281928 DOI: 10.1098/rsos.181540] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 10/16/2018] [Indexed: 06/09/2023]
Abstract
In the tropical forest canopy, wingless worker ants must cling to and run along diverse vegetative surfaces with little protection from sun, wind and rain. Ants rely in part on their tiny adhesive tarsal pads to maintain sufficient contact with substrates to prevent falls under these varied conditions. Here, we examined the effects of substrate wettability and surface water on the tarsal pad adhesive performance of a common tropical arboreal ant. Ant adhesion was consistently higher on an intermediately wetting substrate (static water contact angle ca 90°) when resisting both perpendicular (normal) force and parallel (shear) force. Normal adhesion was maintained on intermediately wetting and hydrophobic substrates following the addition of rain-mimicking water droplets, whereas shear adhesion declined on all substrate types tested after wetting. Ant running speed was slower on wet substrates. On wood substrates, normal and shear adhesion declined with increasing wetness from dry, to misted, to water-soaked. These differences probably contributed to lower ant running speed on wet wood. The results of this study provide the first quantitative assessment of tropical arboreal ant adhesive performance under substrate conditions that are commonly encountered in the rainforest canopy.
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Affiliation(s)
- Alyssa Y. Stark
- Department of Biology, University of Louisville, 139 Life Sciences Building, Louisville, KY 40292, USA
| | - Stephen P. Yanoviak
- Department of Biology, University of Louisville, 139 Life Sciences Building, Louisville, KY 40292, USA
- Smithsonian Tropical Research Institute, Balboa, Republic of Panama
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Langowski JKA, Dodou D, Kamperman M, van Leeuwen JL. Tree frog attachment: mechanisms, challenges, and perspectives. Front Zool 2018; 15:32. [PMID: 30154908 PMCID: PMC6107968 DOI: 10.1186/s12983-018-0273-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/29/2018] [Indexed: 11/16/2022] Open
Abstract
Tree frogs have the remarkable ability to attach to smooth, rough, dry, and wet surfaces using their versatile toe pads. Tree frog attachment involves the secretion of mucus into the pad-substrate gap, requiring adaptations towards mucus drainage and pad lubrication. Here, we present an overview of tree frog attachment, with focus on (i) the morphology and material of the toe pad; (ii) the functional demands on the toe pad arising from ecology, lifestyle, and phylogenetics; (iii) experimental data of attachment performance such as adhesion and friction forces; and (iv) potential perspectives on future developments in the field. By revisiting reported data and observations, we discuss the involved mechanisms of attachment and propose new hypotheses for further research. Among others, we address the following questions: Do capillary and hydrodynamic forces explain the strong friction of the toe pads directly, or indirectly by promoting dry attachment mechanisms? If friction primarily relies on van der Waals (vdW) forces instead, how much do these forces contribute to adhesion in the wet environment tree frogs live in and what role does the mucus play? We show that both pad morphology and measured attachment performance suggest the coaction of several attachment mechanisms (e.g. capillary and hydrodynamic adhesion, mechanical interlocking, and vdW forces) with situation-dependent relative importance. Current analytical models of capillary and hydrodynamic adhesion, caused by the secreted mucus and by environmental liquids, do not capture the contributions of these mechanisms in a comprehensive and accurate way. We argue that the soft pad material and a hierarchical surface pattern on the ventral pad surface enhance the effective contact area and facilitate gap-closure by macro- to nanoscopic drainage of interstitial liquids, which may give rise to a significant contribution of vdW interactions to tree frog attachment. Increasing the comprehension of the complex mechanism of tree frog attachment contributes to a better understanding of other biological attachment systems (e.g. in geckos and insects) and is expected to stimulate the development of a wide array of bioinspired adhesive applications.
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Affiliation(s)
- Julian K. A. Langowski
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Dimitra Dodou
- Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD The Netherlands
| | - Marleen Kamperman
- Physical Chemistry and Soft Matter, Department of Agrotechnology and Food Sciences, Wageningen University & Research, Stippeneng 4, Wageningen, 6708 WE The Netherlands
| | - Johan L. van Leeuwen
- Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
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Voigt D, Gorb S. Functional morphology of tarsal adhesive pads and attachment ability in ticks Ixodes ricinus (Arachnida, Acari, Ixodidae). ACTA ACUST UNITED AC 2018; 220:1984-1996. [PMID: 28566356 DOI: 10.1242/jeb.152942] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/16/2017] [Indexed: 11/20/2022]
Abstract
The presence of well-developed, elastic claws on ticks and widely pilose hosts led us to hypothesise that ticks are mostly adapted to attachment and locomotion on rough, strongly corrugated and hairy, felt-like substrates. However, by using a combination of morphological and experimental approaches, we visualised the ultrastructure of attachment devices of Ixodes ricinus and showed that this species adheres more strongly to smooth surfaces than to rough ones. Between paired, elongated, curved, elastic claws, I. ricinus bears a large, flexible, foldable adhesive pad, which represents an adaptation to adhesion on smooth surfaces. Accordingly, ticks attached strongest to glass and to surface profiles similar to those of the human skin, generating safety factors (attachment force relative to body weight) up to 534 (females). Considerably lower attachment force was found on silicone substrates and as a result of thanatosis after jolting.
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Affiliation(s)
- Dagmar Voigt
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, Kiel D-24098, Germany
| | - Stanislav Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, Kiel D-24098, Germany
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48
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Aita Y, Asanuma N, Mayama H, Nonomura Y. Sliding Profile and Energy at Static Friction between Polymer Surfaces. CHEM LETT 2018. [DOI: 10.1246/cl.171204] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yuuki Aita
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Natsumi Asanuma
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Hiroyuki Mayama
- Department of Chemistry, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan
| | - Yoshimune Nonomura
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
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Sprenger PP, Burkert LH, Abou B, Federle W, Menzel F. Coping with the climate: cuticular hydrocarbon acclimation of ants under constant and fluctuating conditions. ACTA ACUST UNITED AC 2018; 221:jeb.171488. [PMID: 29615527 DOI: 10.1242/jeb.171488] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/29/2018] [Indexed: 11/20/2022]
Abstract
Terrestrial arthropods achieve waterproofing by a layer of cuticular hydrocarbons (CHCs). At the same time, CHCs also serve as communication signals. To maintain waterproofing under different climate conditions, insects adjust the chemical composition of their CHC layer, but this may affect the communication via CHCs. The detailed acclimatory changes of CHCs and how these influence their physical properties are still unknown. Here, we studied acclimation in two closely related ant species with distinct CHC profiles, Myrmica rubra and Myrmica ruginodis, in response to constant or fluctuating temperature and humidity regimes. We measured how acclimation affected CHC composition and viscosity, and the ants' drought survival. In both species, CHC composition showed strong, predictable responses to temperature regimes. Warm-acclimated individuals had higher proportions of linear alkanes, and less methyl-branched or unsaturated CHCs. These changes coincided with higher solid content and viscosity of CHCs in warm-acclimated ants. Temperature fluctuation caused effects similar to those observed under constant-cool conditions in Mrubra, but led to entirely different profiles in Mruginodis, suggesting that fluctuating and constant conditions pose very different challenges. Acclimation to dry conditions led to higher absolute amounts of CHCs, which increased the ants' drought survival, whereas temperature acclimation did not. Hence, the temperature-induced CHC changes cannot be explained by the need for waterproofing alone. Although these changes could be non-adaptive, we propose that they serve to maintain a constant CHC viscosity, which may be essential for communication and other functions.
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Affiliation(s)
- Philipp P Sprenger
- Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Lars H Burkert
- Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Bérengère Abou
- Matière et Systèmes Complexes (MSC), UMR CNRS 7057, Université Paris Diderot, 75205 Paris Cedex 13, France
| | - Walter Federle
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Florian Menzel
- Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University, 55128 Mainz, Germany
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Clemente CJ, Goetzke HH, Bullock JMR, Sutton GP, Burrows M, Federle W. Jumping without slipping: leafhoppers (Hemiptera: Cicadellidae) possess special tarsal structures for jumping from smooth surfaces. J R Soc Interface 2018; 14:rsif.2017.0022. [PMID: 28468924 PMCID: PMC5454290 DOI: 10.1098/rsif.2017.0022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/11/2017] [Indexed: 11/18/2022] Open
Abstract
Many hemipteran bugs can jump explosively from plant substrates, which can be very smooth. We therefore analysed the jumping performance of froghoppers (Philaenus spumarius, Aphrophoridae) and leafhoppers (Aphrodes bicinctus/makarovi, Cicadellidae) taking off from smooth (glass) and rough (sandpaper, 30 µm asperity size) surfaces. On glass, the propulsive hind legs of Philaenus froghoppers slipped, resulting in uncontrolled jumps with a fast forward spin, a steeper angle and only a quarter of the velocity compared with jumps from rough surfaces. By contrast, Aphrodes leafhoppers took off without their propulsive hind legs slipping, and reached low take-off angles and high velocities on both substrates. This difference in jumping ability from smooth surfaces can be explained not only by the lower acceleration of the long-legged leafhoppers, but also by the presence of 2–9 soft pad-like structures (platellae) on their hind tarsi, which are absent in froghoppers. High-speed videos of jumping showed that platellae contact the surface briefly (approx. 3 ms) during the acceleration phase. Friction force measurements on individual hind tarsi on glass revealed that at low sliding speeds, both pushing and pulling forces were small, and insufficient to explain the recorded jumps. Only when the tarsi were pushed with higher velocities did the contact area of the platellae increase markedly, and high friction forces were produced, consistent with the observed jumps. Our findings show that leafhoppers have special adhesive footpads for jumping from smooth surfaces, which achieve firm grip and rapid control of attachment/detachment by combining anisotropic friction with velocity dependence.
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Affiliation(s)
| | | | - James M R Bullock
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Gregory P Sutton
- School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
| | - Malcolm Burrows
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Walter Federle
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
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