1
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Zhao Y, Peng B, Liu L, Fu Y, Zhao T, Chi W, Li D, Ji D, Wang X, Wang D. Scalable Preparation of Liquid Infused Coatings for Lubrication of 10 3 m 2 Dry Ski Slopes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39074038 DOI: 10.1021/acs.langmuir.4c00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/31/2024]
Abstract
To facilitate effective training for freestyle skiers on artificial dry ski slopes, it is crucial to reduce the friction coefficient of the slopes and closely match it with that of snow. Traditional lubrication methods, such as water or soapy water, come with multiple disadvantages, including water waste, which leads to environmental pollution, short-lived effectiveness, and high costs. In this study, we have successfully developed a method for the scalable preparation of a liquid-infused coating (LIC) by tandem spraying inexpensive and environmentally friendly SiO2 particles and silicone oil lubricants. Experimental results showed that the resulting LIC is capable of imparting slippery properties to various surfaces, regardless of the surface chemistry. Moreover, the presence of LIC could reduce the friction coefficient significantly. By carefully regulating the surface composition, we achieved a friction coefficient of 0.059 between a snowboard and the LIC-functionalized ski slope, closely matching that between the snowboard and snow in a typical skiing competition venue (∼0.06). We successfully applied LIC onto 103 m2 dry ski slopes, providing a training ground for professional freestyle skiers.
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Affiliation(s)
- Yuehua Zhao
- Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Bo Peng
- Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Lijun Liu
- Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Yanming Fu
- Department of Kinesiology, Shenyang Sport University, Shenyang 110102, China
| | - Tianyu Zhao
- School of Science, Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China
| | - Weichao Chi
- School of Science, Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China
| | - Dong Li
- School of Science, Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China
| | - Dong Ji
- Winter Sports Administrative Center of the General Administration of Sport of China, Beijing 100044, China
| | - Xin Wang
- Department of Kinesiology, Shenyang Sport University, Shenyang 110102, China
| | - Dapeng Wang
- Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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2
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Borodich FM, Gao Z, Gorb EV, Gorb SN, Jin X. Wax Protrusions on Anti-Adhesive Plant Surfaces and Their Interactions with Insect Adhesive Pads: A Mechanical Interpretation. Biomimetics (Basel) 2024; 9:442. [PMID: 39056883 PMCID: PMC11274746 DOI: 10.3390/biomimetics9070442] [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: 05/30/2024] [Revised: 07/13/2024] [Accepted: 07/16/2024] [Indexed: 07/28/2024] Open
Abstract
Insect attachment devices enhance adhesion to complex-geometry substrates by increasing the real contact area. In nature, insects mainly interact with plant surfaces that are often covered by 3D wax structures. Here, we describe, discuss, and give a mechanical interpretation of plant waxes and the possible fracture mechanisms of these wax structures during their interactions with the adhesive pads of insects. It is argued that these plant surface microstructures significantly influence insect adhesion through reducing the contact area and contaminating the insect pads.
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Affiliation(s)
- Feodor M. Borodich
- College of Aerospace Engineering, Chongqing University, Chongqing 400030, China;
| | - Zaida Gao
- College of Aerospace Engineering, Chongqing University, Chongqing 400030, China;
| | - Elena V. Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, University of Kiel, Am Botanischen Garten 1-9, 24098 Kiel, Germany; (E.V.G.); (S.N.G.)
| | - Stanislav N. Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, University of Kiel, Am Botanischen Garten 1-9, 24098 Kiel, Germany; (E.V.G.); (S.N.G.)
| | - Xiaoqing Jin
- College of Aerospace Engineering, Chongqing University, Chongqing 400030, China;
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3
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Seol JU, Park JS, Lim JH, Hwang HS, Kim EB, Kim SG, Park JI, Sung HC, Kim JH, Kim ES. Dynamic mucus secretion in ventral surfaces of toe pads of the tree frog (Dryophytes japonica). Integr Zool 2024. [PMID: 38556643 DOI: 10.1111/1749-4877.12821] [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] [Indexed: 04/02/2024]
Abstract
The tree frog is a prominent amphibian among terrestrial vertebrates known for its ability to adhere to various surfaces through the capillary forces of water in the microchannels between micropillars on its disc-shaped toe pads, a phenomenon known as wet adhesion. However, the secretion pattern of mucus on the attachment surface of living tree frog toe pads and the distribution of active mucus pores (AMPs) have not yet been fully elucidated. In this study, we utilized synchrotron X-ray micro-computed tomography and interference reflection microscopy to obtain the spatial distribution of the entire population of ventral mucus glands on the toe pads of living tree frogs and the real-time mucus secretion patterns from the ventral mucus pores on the contact surface under different environmental conditions. We observed that the number and secretion frequency of AMPs on the toe pad are regulated according to environmental conditions. Such dynamic mucus secretion on the tree frog's toe pad could contribute to the understanding of capillary force regulation for wet adhesion and the development of adhesive surfaces by mimicking the mucus-secreting toe pad.
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Affiliation(s)
- Jae-Uk Seol
- Department of Biological Sciences, School of Biological Sciences and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
| | - Jung Su Park
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Jae-Hong Lim
- Pohang Accelerator Laboratory, Pohang, Gyeongbuk, Republic of Korea
| | - Hyeon Su Hwang
- Department of Biological Sciences, School of Biological Sciences and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
| | - Eun-Bin Kim
- Department of Biological Sciences, School of Biological Sciences and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
| | - Seob-Gu Kim
- Pohang Accelerator Laboratory, Pohang, Gyeongbuk, Republic of Korea
| | - Jae-Il Park
- Korea Basic Science Institute, Gwangju, Republic of Korea
| | - Ha-Cheol Sung
- Department of Biological Sciences, School of Biological Sciences and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
- Research Center of Ecomimetics, Institute of Sustainable Ecological Environment, Chonnam National University, Gwangju, Republic of Korea
| | - Joon Heon Kim
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea
| | - Eung-Sam Kim
- Department of Biological Sciences, School of Biological Sciences and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
- Research Center of Ecomimetics, Institute of Sustainable Ecological Environment, Chonnam National University, Gwangju, Republic of Korea
- Research Center of Next-Generation Sensors, Chonnam National University, Gwangju, Republic of Korea
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4
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Ma Y, Cao J, Li S, Wang L, Meng Y, Chen Y. Nature-Inspired Wet Drug Delivery Platforms. SMALL METHODS 2024:e2301726. [PMID: 38284322 DOI: 10.1002/smtd.202301726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Indexed: 01/30/2024]
Abstract
Nature has created various organisms with unique chemical components and multi-scale structures (e.g., foot proteins, toe pads, suckers, setose gill lamellae) to achieve wet adhesion functions to adapt to their complex living environments. These organisms can provide inspirations for designing wet adhesives with mediated drug release behaviors in target locations of biological surfaces. They exhibit conformal and enhanced wet adhesion, addressing the bottleneck of weaker tissue interface adhesion in the presence of body fluids. Herein, it is focused on the research progress of different wet adhesion and bioinspired fabrications, including adhesive protein-based adhesion and inspired adhesives (e.g., mussel adhesion); capillarity and Stefan adhesion and inspired adhesive surfaces (e.g., tree frog adhesion); suction-based adhesion and inspired suckers (e.g., octopus' adhesion); interlocking and friction-based adhesion and potential inspirations (e.g., mayfly larva and teleost adhesion). Other secreted protein-induced wet adhesion is also reviewed and various suckers for other organisms and their inspirations. Notably, one representative application scenario of these bioinspired wet adhesives is highlighted, where they function as efficient drug delivery platforms on target tissues and/or organs with requirements of both controllable wet adhesion and optimized drug release. Finally, the challenges of these bioinspired wet drug delivery platforms in the future is presented.
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Affiliation(s)
- Yutian Ma
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jian Cao
- School of Software and Microelectronics, Peking University, Beijing, 100871, China
| | - Shiyao Li
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Lili Wang
- University of Science and Technology of China, Hefei, 230026, China
- Suzhou Institute for Advanced Research, University of Science and Technology of China, Jiangsu, 215123, China
| | - Yufei Meng
- Research Institute of Ornamental Plants and Landscapes, International Centre for Bamboo and Rattan, Beijing, 100102, China
| | - Yupeng Chen
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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5
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Soncini R, Klein W. Surface tension in biological systems - a common problem with a variety of solutions. Comp Biochem Physiol A Mol Integr Physiol 2023; 284:111475. [PMID: 37421990 DOI: 10.1016/j.cbpa.2023.111475] [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: 03/21/2023] [Revised: 07/02/2023] [Accepted: 07/03/2023] [Indexed: 07/10/2023]
Abstract
Water is of fundamental importance to living organisms, not only as a universal solvent to maintain metabolic activity but also due to the effects the physical properties of water have on different organismal structures. In this review, we explore some examples of how living organisms deal with surfaces covered with or in contact with water. While we do not intend to describe all possible forms of interactions in every minute detail, we would like to draw attention to this intriguing interdisciplinary subject and discuss the positive and negative effects of the interaction forces between water molecules and organisms. Topics explored include locomotion on water, wettability of surfaces, benefits of retaining a film of air while submerged (Salvinia effect), surface tension of water inhibiting air-breathing, accumulation of water in small tubes, surface tension in non-mammalian and mammalian respiratory systems. In each topic, we address the importance of interactions with water and the adaptations seen in an organism to solve the surface-related challenges, trying to explore the different selective pressures acting onto different organisms allowing exploring or compensating these surface-related interactions.
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Affiliation(s)
- Roseli Soncini
- Instituto de Ciências Biomédicas, Universidade Federal de Alfenas, Alfenas, MG, Brazil
| | - Wilfried Klein
- Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
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6
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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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7
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Nguyen VP, Dhyan SB, Mai V, Han BS, Chow WT. Bioinspiration and Biomimetic Art in Robotic Grippers. MICROMACHINES 2023; 14:1772. [PMID: 37763934 PMCID: PMC10535325 DOI: 10.3390/mi14091772] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/07/2023] [Accepted: 09/09/2023] [Indexed: 09/29/2023]
Abstract
The autonomous manipulation of objects by robotic grippers has made significant strides in enhancing both human daily life and various industries. Within a brief span, a multitude of research endeavours and gripper designs have emerged, drawing inspiration primarily from biological mechanisms. It is within this context that our study takes centre stage, with the aim of conducting a meticulous review of bioinspired grippers. This exploration involved a nuanced classification framework encompassing a range of parameters, including operating principles, material compositions, actuation methods, design intricacies, fabrication techniques, and the multifaceted applications into which these grippers seamlessly integrate. Our comprehensive investigation unveiled gripper designs that brim with a depth of intricacy, rendering them indispensable across a spectrum of real-world scenarios. These bioinspired grippers with a predominant emphasis on animal-inspired solutions have become pivotal tools that not only mirror nature's genius but also significantly enrich various domains through their versatility.
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Affiliation(s)
- Van Pho Nguyen
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore or (V.P.N.); (S.B.D.)
- Schaeffler Hub for Advanced Research at NTU, Singapore 637460, Singapore;
| | - Sunil Bohra Dhyan
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore or (V.P.N.); (S.B.D.)
- Schaeffler Hub for Advanced Research at NTU, Singapore 637460, Singapore;
| | - Vu Mai
- Faculty of Engineering, Dong Nai Technology University, Bien Hoa City 76000, Vietnam;
| | - Boon Siew Han
- Schaeffler Hub for Advanced Research at NTU, Singapore 637460, Singapore;
| | - Wai Tuck Chow
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore or (V.P.N.); (S.B.D.)
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8
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Su B, Ye J, Zou X, Huang L, Wang X. Effect of bionic hexagonal texture on squeezing films inside soft contacts with high adhesion and high friction. SOFT MATTER 2023. [PMID: 37314179 DOI: 10.1039/d3sm00154g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
To understand the mechanisms of high friction and high adhesion in bioinspired textured surfaces under wet conditions, the evolution behavior of squeezing films across lubricated interfaces is experimentally investigated using optical interferometry. The results show that the splitting of the continuous large-scaled liquid film into numerous isolated micro zones is an important function of the hexagonal texture. Both the orientation and the size of the hexagonal texture have noticeable effects on the drainage rate: either downscaling the hexagonal texture or orienting the texture with two sides of each micro-hexagon parallel to the inclining direction could accelerate the draining process. While the draining process is completed, residual micro-droplets turn out to be entrapped within the contact regions of single hexagonal micro-pillars. The entrapped micro-droplets gradually shrink as the hexagonal texture downsizes. Moreover, a novel geometrical shape for the micro-pillared texture is proposed to improve the drainage efficiency.
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Affiliation(s)
- Binbin Su
- Jiangxi province key laboratory of maglev technology, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
- School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
| | - Jianhe Ye
- Jiangxi province key laboratory of maglev technology, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
- School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
| | - Xianghe Zou
- School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
| | - Lirong Huang
- School of mechanical and electrical engineering, Jiangxi University of Science and Technology, Ganzhou 341000, People's Republic of China
| | - Xiaolei Wang
- College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People's Republic of China.
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9
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Clifton G, Stark AY, Li C, Gravish N. The bumpy road ahead: the role of substrate roughness on animal walking and a proposed comparative metric. J Exp Biol 2023; 226:307149. [PMID: 37083141 DOI: 10.1242/jeb.245261] [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] [Indexed: 04/22/2023]
Abstract
Outside laboratory conditions and human-made structures, animals rarely encounter flat surfaces. Instead, natural substrates are uneven surfaces with height variation that ranges from the microscopic scale to the macroscopic scale. For walking animals (which we define as encompassing any form of legged movement across the ground, such as walking, running, galloping, etc.), such substrate 'roughness' influences locomotion in a multitude of ways across scales, from roughness that influences how each toe or foot contacts the ground, to larger obstacles that animals must move over or navigate around. Historically, the unpredictability and variability of natural environments has limited the ability to collect data on animal walking biomechanics. However, recent technical advances, such as more sensitive and portable cameras, biologgers, laboratory tools to fabricate rough terrain, as well as the ability to efficiently store and analyze large variable datasets, have expanded the opportunity to study how animals move under naturalistic conditions. As more researchers endeavor to assess walking over rough terrain, we lack a consistent approach to quantifying roughness and contextualizing these findings. This Review summarizes existing literature that examines non-human animals walking on rough terrain and presents a metric for characterizing the relative substrate roughness compared with animal size. This framework can be applied across terrain and body scales, facilitating direct comparisons of walking over rough surfaces in animals ranging in size from ants to elephants.
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Affiliation(s)
| | | | - Chen Li
- Department of Mechanical Engineering, Johns Hopkins University, MD, USA
| | - Nicholas Gravish
- Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA, USA
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10
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Glaser NC, Langowski JKA. Stiff skin, soft core: soft backings enhance the conformability and friction of fibre-reinforced adhesives. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221263. [PMID: 36908990 PMCID: PMC9993060 DOI: 10.1098/rsos.221263] [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: 10/26/2022] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Biomimetic adhesives with a stiff fibre-reinforced base layer generate strong attachment, even without bioinspired micropatterning of the contact surface. However, current fibre-reinforced adhesive designs are still less versatile with respect to substrate variability than their biological counterparts. In this study, we enhance the comformability of a fibre-reinforced adhesive on curved substrates by adding bioinspired soft backings. We designed and fabricated soft backing variations (polyurethane foams and silicone hydroskeletons) with varying compressive stiffnesses that mimic the soft viscoelastic structures in the adhesive appendages of tree frogs, geckos and other animals. The backings were mounted on a smooth silicone layer enforced with a polyester mesh, and we experimentally investigated the contact area and friction performance of these adhesives on a curved substrate. The results show that the contact area and friction created by a fibre-reinforced adhesive with a soft backing in contact with a non-flat substrate scale inversely with backing stiffness. The integration of stiff fibre-reinforcement with a compressible backing represents an important step in bringing bioinspired adhesives out of the laboratory and into the real world, for example in soft robotic grippers. Moreover, our findings stimulate further research into the role of soft tissues in biological adhesive systems.
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Affiliation(s)
- Niels C. Glaser
- 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 and Research, De Elst 1, 6708 WD Wageningen, The Netherlands
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11
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Orndorf N, Garner AM, Dhinojwala A. Polar bear paw pad surface roughness and its relevance to contact mechanics on snow. J R Soc Interface 2022; 19:20220466. [PMID: 36321372 PMCID: PMC9627446 DOI: 10.1098/rsif.2022.0466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 10/11/2022] [Indexed: 11/04/2023] Open
Abstract
Microscopic papillae on polar bear paw pads are considered adaptations for increased friction on ice/snow, yet this assertion is based on a single study of one species. The lack of comparative data from species that exploit different habitats renders the ecomorphological associations of papillae unclear. Here, we quantify the surface roughness of the paw pads of four species of bear over five orders of magnitude by calculating their surface roughness power spectral density. We find that interspecific variation in papillae base diameter can be explained by paw pad width, but that polar bear paw pads have 1.5 times taller papillae and 1.3 times more true surface area than paw pads of the American black bear and brown bear. Based on friction experiments with three-dimensional printed model surfaces and snow, we conclude that these factors increase the frictional shear stress of the polar bear paw pad on snow by a factor of 1.3-1.5 compared with the other species. Absolute frictional forces, however, are estimated to be similar among species once paw pad area is accounted for, suggesting that taller papillae may compensate for frictional losses resulting from the relatively smaller paw pads of polar bears compared with their close relatives.
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Affiliation(s)
- Nathaniel Orndorf
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325, USA
| | - Austin M. Garner
- Integrated Bioscience Program, Department of Biology, The University of Akron, Akron, OH 44325, USA
| | - Ali Dhinojwala
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325, USA
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12
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Montazerian H, Davoodi E, Baidya A, Badv M, Haghniaz R, Dalili A, Milani AS, Hoorfar M, Annabi N, Khademhosseini A, Weiss PS. Bio-macromolecular design roadmap towards tough bioadhesives. Chem Soc Rev 2022; 51:9127-9173. [PMID: 36269075 PMCID: PMC9810209 DOI: 10.1039/d2cs00618a] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Emerging sutureless wound-closure techniques have led to paradigm shifts in wound management. State-of-the-art biomaterials offer biocompatible and biodegradable platforms enabling high cohesion (toughness) and adhesion for rapid bleeding control as well as robust attachment of implantable devices. Tough bioadhesion stems from the synergistic contributions of cohesive and adhesive interactions. This Review provides a biomacromolecular design roadmap for the development of tough adhesive surgical sealants. We discuss a library of materials and methods to introduce toughness and adhesion to biomaterials. Intrinsically tough and elastic polymers are leveraged primarily by introducing strong but dynamic inter- and intramolecular interactions either through polymer chain design or using crosslink regulating additives. In addition, many efforts have been made to promote underwater adhesion via covalent/noncovalent bonds, or through micro/macro-interlock mechanisms at the tissue interfaces. The materials settings and functional additives for this purpose and the related characterization methods are reviewed. Measurements and reporting needs for fair comparisons of different materials and their properties are discussed. Finally, future directions and further research opportunities for developing tough bioadhesive surgical sealants are highlighted.
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Affiliation(s)
- Hossein Montazerian
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
- Terasaki Institute for Biomedical Innovation, Los Angeles, Los Angeles, California 90024, USA.
| | - Elham Davoodi
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
- Terasaki Institute for Biomedical Innovation, Los Angeles, Los Angeles, California 90024, USA.
- Multi-Scale Additive Manufacturing Lab, Mechanical and Mechatronics Engineering Department, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Avijit Baidya
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
| | - Maryam Badv
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Biomedical Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Reihaneh Haghniaz
- Terasaki Institute for Biomedical Innovation, Los Angeles, Los Angeles, California 90024, USA.
| | - Arash Dalili
- School of Engineering, University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
| | - Abbas S Milani
- School of Engineering, University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
| | - Mina Hoorfar
- School of Engineering, University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
- School of Engineering and Computer Science, University of Victoria, Victoria, British Columbia V8P 3E6, Canada
| | - Nasim Annabi
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
| | - Ali Khademhosseini
- Terasaki Institute for Biomedical Innovation, Los Angeles, Los Angeles, California 90024, USA.
| | - Paul S Weiss
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA
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13
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Vallet Y, Laurent C, Bertholdt C, Rahouadj R, Morel O. Analysis of suction-based gripping strategies in wildlife towards future evolutions of the obstetrical suction cup. BIOINSPIRATION & BIOMIMETICS 2022; 17:061003. [PMID: 36206746 DOI: 10.1088/1748-3190/ac9878] [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: 02/10/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
The design of obstetrical suction cups used for vacuum assisted delivery has not substantially evolved through history despite of its inherent limitations. The associated challenges concern both the decrease of risk of soft tissue damage and failure of instrumental delivery due to detachment of the cup. The present study firstly details some of the suction-based strategies that have been developed in wildlife in order to create and maintain an adhesive contact with potentially rough and uneven substratum in dry or wet environments. Such strategies have permitted the emergence of bioinspired suction-based devices in the fields of robotics or biomedical patches that are briefly reviewed. The objective is then to extend the observations of such suction-based strategies toward the development of innovative medical suction cups. We firstly conclude that the overall design, shape and materials of the suction cups could be largely improved. We also highlight that the addition of a patterned surface combined with a viscous fluid at the interface between the suction cup and scalp could significantly limit the detachment rate and the differential pressure required to exert a traction force. In the future, the development of a computational model including a detailed description of scalp properties should allow to experiment various designs of bioinspired suction cups.
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Affiliation(s)
- Y Vallet
- CNRS UMR 7239 LEM3-Université de Lorraine, Nancy, France
| | - C Laurent
- CNRS UMR 7239 LEM3-Université de Lorraine, Nancy, France
| | - C Bertholdt
- Université de Lorraine, CHRU-NANCY, Pôle de la Femme, F-54000 Nancy, France
- IADI, INSERM U1254, Rue du Morvan, 54500 Vandoeuvre-lès-Nancy, France
| | - R Rahouadj
- CNRS UMR 7239 LEM3-Université de Lorraine, Nancy, France
| | - O Morel
- Université de Lorraine, CHRU-NANCY, Pôle de la Femme, F-54000 Nancy, France
- IADI, INSERM U1254, Rue du Morvan, 54500 Vandoeuvre-lès-Nancy, France
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14
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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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15
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Frey ST, Haque ABMT, Tutika R, Krotz EV, Lee C, Haverkamp CB, Markvicka EJ, Bartlett MD. Octopus-inspired adhesive skins for intelligent and rapidly switchable underwater adhesion. SCIENCE ADVANCES 2022; 8:eabq1905. [PMID: 35857521 PMCID: PMC9278861 DOI: 10.1126/sciadv.abq1905] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 06/01/2022] [Indexed: 05/21/2023]
Abstract
The octopus couples controllable adhesives with intricately embedded sensing, processing, and control to manipulate underwater objects. Current synthetic adhesive-based manipulators are typically manually operated without sensing or control and can be slow to activate and release adhesion, which limits system-level manipulation. Here, we couple switchable, octopus-inspired adhesives with embedded sensing, processing, and control for robust underwater manipulation. Adhesion strength is switched over 450× from the ON to OFF state in <50 ms over many cycles with an actively controlled membrane. Systematic design of adhesive geometry enables adherence to nonideal surfaces with low preload and independent control of adhesive strength and adhesive toughness for strong and reliable attachment and easy release. Our bio-inspired nervous system detects objects and autonomously triggers the switchable adhesives. This is implemented into a wearable glove where an array of adhesives and sensors creates a biomimetic adhesive skin to manipulate diverse underwater objects.
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Affiliation(s)
- Sean T. Frey
- Materials Science and Engineering, Iowa State University, Ames, IA 50010, USA
| | - A. B. M. Tahidul Haque
- Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg, VA 24061, USA
| | - Ravi Tutika
- Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg, VA 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Elizabeth V. Krotz
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Chanhong Lee
- Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg, VA 24061, USA
| | - Cole B. Haverkamp
- Materials Science and Engineering, Iowa State University, Ames, IA 50010, USA
| | - Eric J. Markvicka
- Department of Mechanical and Materials Engineering, Smart Materials and Robotics Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Michael D. Bartlett
- Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg, VA 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
- Corresponding author.
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16
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Why link diverse citizen science surveys? Widespread arboreal habits of a terrestrial amphibian revealed by mammalian tree surveys in Britain. PLoS One 2022; 17:e0265156. [PMID: 35793361 PMCID: PMC9258833 DOI: 10.1371/journal.pone.0265156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/17/2022] [Indexed: 11/19/2022] Open
Abstract
Terrestrial anurans, with their typically short limbs, heavy-set bodies and absent claws or toe pads are incongruous tree climbers, but even occasional arboreal locomotion could offer substantial advantages for evading predators or accessing new shelter or food resources. Despite recent interest, arboreal behaviour remains rarely and unsystematically described for terrestrial amphibians in Europe, likely due to fundamental differences in survey methods and therefore a lack of field data. However, other taxa surveys specifically target trees and tree cavities. We undertook collaborations and large-scale data searches with two major citizen science projects surveying for arboreal mammals in Britain to investigate potential tree climbing by amphibians at a national scale. Remarkably, we found widespread arboreal usage by amphibians in England and Wales, with occupancy of hazel dormouse (Muscardinus avellenarius) nest boxes, tree cavities investigated as potential bat roosts and even a bird nest, by common toads (Bufo bufo), but few additional records of frogs or newts. Of the 277–400 sites surveyed annually for dormice since 2009 at least 18 sites had amphibians recorded in nest boxes while of the 1388 trees surveyed for bats a total 1.4% (19 trees) had toads present. Common toads were found using cavities in seven tree species and especially goat willow (Salix caprea). Toads are potentially attracted to tree cavities and arboreal nests because they provide safe and damp microenvironments which can support an abundance of invertebrate prey but the importance of such tree microhabitats for toad conservation remains unknown and our results should be interpreted cautiously. We encourage expanding and linking of unrelated biodiversity monitoring surveys and citizen science initiatives as valuable tools for investigating ecological traits and interactions.
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17
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18
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Graphene-Based Flexible Electrode for Electrocardiogram Signal Monitoring. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094526] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
With the rapidly aging society and increased concern for personal cardiovascular health, novel, flexible electrodes suitable for electrocardiogram (ECG) signal monitoring are in demand. Based on the excellent electrical and mechanical properties of graphene and the rapid development of graphene device fabrication technologies, graphene-based ECG electrodes have recently attracted much attention, and many flexible graphene electrodes with excellent performance have been developed. To understand the current research progress of graphene-based ECG electrodes and help researchers clarify current development conditions and directions, we systematically review the recent advances in graphene-based flexible ECG electrodes. Graphene electrodes are classified as bionic, fabric-based, biodegradable, laser-induced/scribed, modified-graphene, sponge-like, invasive, etc., based on their design concept, structural characteristics, preparation methods, and material properties. Moreover, some categories are further divided into dry or wet electrodes. Then, their performance, including electrode–skin impedance, signal-to-noise ratio, skin compatibility, and stability, is analyzed. Finally, we discuss possible development directions of graphene ECG electrodes and share our views.
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19
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Wang Y, Hensel R, Arzt E. Attachment of bioinspired microfibrils in fluids: transition from a hydrodynamic to hydrostatic mechanism. J R Soc Interface 2022; 19:20220050. [PMID: 35382580 PMCID: PMC8984370 DOI: 10.1098/rsif.2022.0050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reversible and switchable adhesion of elastomeric microstructures has attracted significant interest in the development of grippers for object manipulation. Their applications, however, have often been limited to dry conditions and adhesion of such deformable microfibrils in the fluid environment is less understood. In the present study, we performed adhesion tests in silicone oil using single cylindrical microfibrils of a flat-punch shape with a radius of 80 µm. Stiff fibrils were created using three-dimensional printing of an elastomeric resin with an elastic modulus of 500 MPa, and soft fibrils, with a modulus of 3.3 MPa, were moulded in polyurethane. Our results suggest that adhesion is dominated by hydrodynamic forces, which can be maximized by stiff materials and high retraction velocities, in line with theoretical predictions. The maximum pull-off stress of stiff cylindrical fibrils is 0.6 MPa, limited by cavitation and viscous fingering, occurring at retraction velocities greater than 2 µm s-1. Next, we add a mushroom cap to the microfibrils, which, in the case of the softer material, deforms upon retraction and leads to a transition to a hydrostatic suction regime with higher pull-off stresses ranging from 0.7 to 0.9 MPa. The effects of elastic modulus, fibril size and viscosity for underwater applications are illustrated in a mechanism map to provide guidance for design optimization.
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Affiliation(s)
- Yue Wang
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - René Hensel
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Eduard Arzt
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.,Department of Materials Science and Engineering, Saarland University, Campus D2 2, 66123 Saarbrücken, Germany
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20
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Sandoval JA, Xu T, Adibnazari I, Deheyn DD, Tolley MT. Combining Suction and Friction to Stabilize a Soft Gripper to Shear and Normal Forces, for Manipulation of Soft Objects in Wet Environments. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3149306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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21
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Khan MN, Huo T, Zhang Q, Hu Z, Zhao J, Chen J, Wang Z, Ji K. Synergetic adhesion in highly adaptable bio-inspired adhesive. Colloids Surf B Biointerfaces 2022; 212:112335. [PMID: 35078054 DOI: 10.1016/j.colsurfb.2022.112335] [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: 11/15/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 10/19/2022]
Abstract
Biologically inspired adhesives microstructure requires enough flexibility to make a conformal attachment to the surface as well as high rigidity to maintain the mechanical stability of structure against buckling. To tackle these conflicting factors for the synthetic adhesives is a challenge towards large-scale production and utilizing in practical applications. Addressing this problem, we have fabricated a honeycomb structure with a soft elastic film, partially covering the cavity of the honeycomb pattern. Honeycomb structure provides enough support to maintain the structural stability of the microstructure and soft PDMS film over the pattern provides sufficient flexibility to form a strong attachment with the target surface. Meanwhile, the resemblance of the designed structure to the octopi's sucker generates a negative pressure resulting in suction forces. To justify this suction effect, we compared our results with other controlled honeycomb microstructures (1) without any elastic film (2) with elastic film covering the whole cavity of the honeycomb pattern. Experimental results and theoretical prediction demonstrate the synergistic role of van der Waals and suction forces in the proposed partial-film honeycomb microstructure. The synergistic role of adhesive forces makes this structure a stronger, durable, and surface adaptable adhesive. We also investigated the critical role of the viscous forces for our proposed microstructure in water and silicon oil wetting conditions which signify the contribution of capillary forces.
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Affiliation(s)
- Muhammad Niaz Khan
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Tingwei Huo
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Qian Zhang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Zhuoyang Hu
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Jiahui Zhao
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Jian Chen
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Zhouyi Wang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Keju Ji
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
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22
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Darby DR, Cai Z, Mason CR, Pham JT. Modulus and adhesion of Sylgard 184, Solaris, and Ecoflex 00‐30 silicone elastomers with varied mixing ratios. J Appl Polym Sci 2022. [DOI: 10.1002/app.52412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Daniel R. Darby
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Zhuoyun Cai
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Christopher R. Mason
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
| | - Jonathan T. Pham
- Department of Chemical and Materials Engineering University of Kentucky Lexington Kentucky USA
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23
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Jumping with adhesion: landing surface incline alters impact force and body kinematics in crested geckos. Sci Rep 2021; 11:23043. [PMID: 34845262 PMCID: PMC8630229 DOI: 10.1038/s41598-021-02033-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/29/2021] [Indexed: 11/20/2022] Open
Abstract
Arboreal habitats are characterized by a complex three-dimensional array of branches that vary in numerous characteristics, including incline, compliance, roughness, and diameter. Gaps must often be crossed, and this is frequently accomplished by leaping. Geckos bearing an adhesive system often jump in arboreal habitats, although few studies have examined their jumping biomechanics. We investigated the biomechanics of landing on smooth surfaces in crested geckos, Correlophus ciliatus, asking whether the incline of the landing platform alters impact forces and mid-air body movements. Using high-speed videography, we examined jumps from a horizontal take-off platform to horizontal, 45° and 90° landing platforms. Take-off velocity was greatest when geckos were jumping to a horizontal platform. Geckos did not modulate their body orientation in the air. Body curvature during landing, and landing duration, were greatest on the vertical platform. Together, these significantly reduced the impact force on the vertical platform. When landing on a smooth vertical surface, the geckos must engage the adhesive system to prevent slipping and falling. In contrast, landing on a horizontal surface requires no adhesion, but incurs high impact forces. Despite a lack of mid-air modulation, geckos appear robust to changing landing conditions.
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24
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Cai C, Chen Z, Chen Y, Li H, Yang Z, Liu H. Mechanisms and applications of bioinspired underwater/wet adhesives. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210521] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Chao Cai
- State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China
| | - Zhen Chen
- State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China
| | - Yujie Chen
- State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China
| | - Hua Li
- State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China
| | - Zhi Yang
- Department of Oral and Cranio‐maxillofacial Surgery Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology National Clinical Research Center of Stomatology Shanghai China
| | - Hezhou Liu
- State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai China
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25
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Zhang B, Jia L, Jiang J, Wu S, Xiang T, Zhou S. Biomimetic Microstructured Hydrogels with Thermal-Triggered Switchable Underwater Adhesion and Stable Antiswelling Property. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36574-36586. [PMID: 34304555 DOI: 10.1021/acsami.1c10051] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The design of hydrogels with switchable adhesion and stable antiswelling property in a wet environment has remained a challenge. Here, we report a biomimetic hydrogel that can adhere and detach on-demand on various material surfaces, which is realized by thermal-triggered switchable shape transformation on hexagonal micropillar patterned hydrogels. The hydrogels are cross-linked by two cross-linkers of poly(ethylene glycol) dimethacrylate and 2-ureidoethyl methacrylate, which guarantee the strong mechanical property and stable antiswelling property in a wet environment. The hydrogels can maintain stable water content in solutions with variable pH, temperature, and salt concentration, and the change in volume does not exceed 2%. In addition, due to the dynamical hydrogen bonds and dipole-dipole interaction in the hydrogels, the hydrogels exhibit a thermal-triggered shape-memory effect. The hydrogel can recover shape more than 80% in 15 s. Furthermore, inspired by the surface structure of tree-frog footpads, the hexagonal micropillar patterned hydrogels exhibit improved underwater adhesion strength. The underwater adhesion strength of hexagonal micropillar patterned hydrogels is seven times more than that of flat hydrogels. Based on the shape-memory effect of hydrogels, the adhesion strength can be altered by a thermal stimulus. The adhesion strength of the microstructures recovered from the hydrogel surface decreased to 15.4% of the initial adhesion strength. The switchable underwater adhesion of hydrogels can be applied in the fields of transfer printing, medical adhesives, mobile robots, etc.
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Affiliation(s)
- Bo Zhang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Lianghao Jia
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Jinrui Jiang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Shanshan Wu
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Tao Xiang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Shaobing Zhou
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
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26
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27
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28
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Tree frog-inspired nanopillar arrays for enhancement of adhesion and friction. Biointerphases 2021; 16:021001. [PMID: 33706530 DOI: 10.1116/6.0000747] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Bioinspired structure adhesives have received increasing interest for many applications, such as climbing robots and medical devices. Inspired by the closely packed keratin nanopillars on the toe pads of tree frogs, tightly arranged polycaprolactone nanorod arrays are prepared by mold process and chemical modification. Nanorod arrays show enhanced adhesion and friction on both smooth and rough surfaces compared to the arrays with hexagonal micropillars. The bonding of nanorods results in a larger stiffness of the nanorod surface, contributing mainly to friction rather than adhesion. The results suggest the function of closely packed keratin nanopillars on the toe pad of tree frogs and offer a guiding principle for the designing of new structured adhesives with strong attaching abilities.
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29
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Li M, Shi L, Wang X. Physical mechanisms behind the wet adhesion: From amphibian toe-pad to biomimetics. Colloids Surf B Biointerfaces 2021; 199:111531. [PMID: 33383551 DOI: 10.1016/j.colsurfb.2020.111531] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/01/2020] [Accepted: 12/06/2020] [Indexed: 10/22/2022]
Abstract
Some amphibians, such as tree frogs, torrent frogs, newts, are able to climb or attach to wet slippery smooth surfaces, even in a vertical or overhanging state, by their reliable reversible adhesions developed on the epidermal of toe pads. It is widely believed that such outstanding function originates from the possible factors of the specialized evolutions of surficial micro/nanostructures, the chemical components of secreted mucus, the solid-liquid behavior of epidermal and the bulk softness of toe pads. In this review, we summarize the main physical mechanisms of these factors behaving underlying the wet adhesion of toe pads from the researches on biological models to artificial counterparts. The discussion of the organism attachments, the interfacial physical forces and the switchable strategies for artificial wet adhesion are also included. The paper gives a deeply, comprehensively understanding of the characters of wet adhesives on amphibians, which performs necessarily for the new strategies of exploring artificial adhesive surfaces.
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Affiliation(s)
- Meng Li
- School of Mechanical Engineering, Anhui University of Technology, Ma'anshan, 243032, China; International Science and Technology Cooperation Base for Intelligent Equipment Manufacturing in Special Service Environment, Ma'anshan, 243032, China; Anhui Province Key Laboratory of Special and Heavy Load Robot, Ma'anshan, 243032, China
| | - Liping Shi
- School of Mechanical Engineering, Anhui University of Technology, Ma'anshan, 243032, China; International Science and Technology Cooperation Base for Intelligent Equipment Manufacturing in Special Service Environment, Ma'anshan, 243032, China; Anhui Province Key Laboratory of Special and Heavy Load Robot, Ma'anshan, 243032, China.
| | - Xiaolei Wang
- College of Mechanical & Electrical Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, China.
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30
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Chudak M, Chopra V, Hensel R, Darhuber AA. Elastohydrodynamic Dewetting of Thin Liquid Films: Elucidating Underwater Adhesion of Topographically Patterned Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11929-11937. [PMID: 32903008 PMCID: PMC7558345 DOI: 10.1021/acs.langmuir.0c02005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/14/2020] [Indexed: 06/11/2023]
Abstract
In underwater adhesion of a topographically patterned surface with a very soft material such as human skin, the elastic deformation can be large enough to achieve solid-on-solid contact not only on top of the hills but also in the valleys of the substrate topography. In this context, we have studied the dynamics of dewetting of a thin liquid film confined between a rigid, periodic micropillar array and a soft, elastic sphere. In our experiments, we observed two very distinct dewetting morphologies. For large ratios of array period to micropillar height and width, the dewetted areas tend to have a diamond-like shape and expand with a rate similar to a flat, unpatterned substrate. When the array period is reduced, the morphology of the dry spot becomes irregular and its expansion rate is significantly reduced. We developed a fully coupled numerical model of the dewetting process that reproduces the key features observed in experiments. Moreover, we performed contact mechanics simulations to characterize the deformation of the elastomer and the shape of the dewetted area in a unit cell of the micropillar array.
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Affiliation(s)
- Maciej Chudak
- Department
of Applied Physics, Eindhoven University
of Technology, 5600MB Eindhoven, The Netherlands
| | - Vaishali Chopra
- INM
- Leibniz Institute for New Materials, Saarbrücken 66123, Germany
| | - René Hensel
- INM
- Leibniz Institute for New Materials, Saarbrücken 66123, Germany
| | - Anton A. Darhuber
- Department
of Applied Physics, Eindhoven University
of Technology, 5600MB Eindhoven, The Netherlands
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31
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Sandoval JA, Sommers J, Peddireddy KR, Robertson-Anderson RM, Tolley MT, Deheyn DD. Toward Bioinspired Wet Adhesives: Lessons from Assessing Surface Structures of the Suction Disc of Intertidal Clingfish. ACS APPLIED MATERIALS & INTERFACES 2020; 12:45460-45475. [PMID: 32910638 DOI: 10.1021/acsami.0c10749] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The clingfish attaches to rough surfaces with considerable strength using an intricate suction disc, which displays complex surface geometries from structures called papillae. However, the exact role of these structures in adhesion is poorly understood. To investigate the relationship between papillae geometry and adhesive performance, we developed an image processing tool that analyzed the surface and structural complexity of papillae, which we then used to model hydrodynamic adhesion. Our tool allowed for the automated analysis of thousands of papillae in specimens across a range of body sizes. The results led us to identify spatial trends in papillae across the complex geometry of the suction disc and to establish fundamental structure-function relationships used in hydrodynamic adhesion. We found that the surface area of papillae changed within a suction disc and with fish size, but that the aspect ratios and channel width between papillae did not. Using a mathematical model, we found that the surface structures can adhere considerably when subjected to disturbances of moderate to high velocities. We concluded that a predominant role of the papillae is to leverage hydrodynamic adhesion and wet friction to reinforce the seal of the suction disc. Overall, the trends in papillae characteristics provided insights into bioinspired designs of surface microstructures for future applications in which adhesion is necessary to attach to diverse surfaces (in terrestrial or aquatic environments), even when subjected to disturbance forces of randomized directionality.
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Affiliation(s)
- Jessica A Sandoval
- Materials Science and Engineering Program, Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Jade Sommers
- Department of Mechanical Engineering, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, United States
| | - Karthik R Peddireddy
- Department of Physics and Biophysics, University of San Diego, 5998 Alcala Park, San Diego, California 92110, United States
| | - Rae M Robertson-Anderson
- Department of Physics and Biophysics, University of San Diego, 5998 Alcala Park, San Diego, California 92110, United States
| | - Michael T Tolley
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
- Materials Science and Engineering Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Dimitri D Deheyn
- Marine Biology Research Division, Scripps Institution of Oceanography, UC San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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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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Langowski JKA, Dodou D, van Assenbergh P, van Leeuwen JL. Design of Tree-Frog-Inspired Adhesives. Integr Comp Biol 2020; 60:906-918. [PMID: 32413122 PMCID: PMC7751017 DOI: 10.1093/icb/icaa037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The adhesive toe pads of tree frogs have inspired the design of various so-called ‘smooth’ synthetic adhesives for wet environments. However, these adhesives do not reach the attachment performance of their biological models in terms of contact formation, maintenance of attachment, and detachment. In tree frogs, attachment is facilitated by an interconnected ensemble of superficial and internal morphological components, which together form a functional unit. To help bridging the gap between biological and bioinspired adhesives, in this review, we (1) provide an overview of the functional components of tree frog toe pads, (2) investigate which of these components (and attachment mechanisms implemented therein) have already been transferred into synthetic adhesives, and (3) highlight functional analogies between existing synthetic adhesives and tree frogs regarding the fundamental mechanisms of attachment. We found that most existing tree-frog-inspired adhesives mimic the micropatterned surface of the ventral epidermis of frog pads. Geometrical and material properties differ between these synthetic adhesives and their biological model, which indicates similarity in appearance rather than function. Important internal functional components such as fiber-reinforcement and muscle fibers for attachment control have not been considered in the design of tree-frog-inspired adhesives. Experimental work on tree-frog-inspired adhesives suggests that the micropatterning of adhesives with low-aspect-ratio pillars enables crack arresting and the drainage of interstitial liquids, which both facilitate the generation of van der Waals forces. Our analysis of experimental work on tree-frog-inspired adhesives indicates that interstitial liquids such as the mucus secreted by tree frogs play a role in detachment. Based on these findings, we provide suggestions for the future design of biomimetic adhesives. Specifically, we propose to implement internal fiber-reinforcements inspired by the fibrous structures in frog pads to create mechanically reinforced soft adhesives for high-load applications. Contractile components may stimulate the design of actuated synthetic adhesives with fine-tunable control of attachment strength. An integrative approach is needed for the design of tree-frog-inspired adhesives that are functionally analogous with their biological paradigm.
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Affiliation(s)
- Julian K A Langowski
- Experimental Zoology Group, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD, The Netherlands
| | - Dimitra Dodou
- Department of BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands
| | - Peter van Assenbergh
- Department of BioMechanical Engineering, Delft University of Technology, Mekelweg 2, Delft, 2628 CD, The Netherlands
| | - Johan L van Leeuwen
- Experimental Zoology Group, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD, The Netherlands
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Zhang L, Chen H, Guo Y, Wang Y, Jiang Y, Zhang D, Ma L, Luo J, Jiang L. Micro-Nano Hierarchical Structure Enhanced Strong Wet Friction Surface Inspired by Tree Frogs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2001125. [PMID: 33101853 PMCID: PMC7578903 DOI: 10.1002/advs.202001125] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/12/2020] [Indexed: 05/07/2023]
Abstract
Superior wet attachment and friction performance without the need of special external or preloaded normal force, similar to the tree frog's toe pad, is highly essential for biomedical engineering, wearable flexible electronics, etc. Although various pillar surfaces are proposed to enhance wet adhesion or friction, their mechanisms remain on micropillar arrays to extrude interfacial liquid via an external force. Here, two-level micropillar arrays with nanocavities on top are discovered on the toe pads of a tree frog, and they exhibit strong boundary friction ≈20 times higher than dry and wet friction without the need of a special external or preloaded normal force. Microscale in situ observations show that the specific micro-nano hierarchical pillars in turn trigger three-level liquid adjusting phenomena, including two-level liquid self-splitting and liquid self-sucking effects. Under these effects, uniform nanometer-thick liquid bridges form spontaneously on all pillars to generate strong boundary friction, which can be ≈2 times higher than for single-level pillar surfaces and ≈3.5 times higher than for smooth surfaces. Finally, theoretical models of boundary friction in terms of self-splitting and self-sucking are built to reveal the importance of liquid behavior induced by micro-nano hierarchical structure.
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Affiliation(s)
- Liwen Zhang
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
| | - Huawei Chen
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
- Beijing Advanced Innovation Center for Biomedical EngineeringBeihang UniversityBeijing100191China
| | - Yurun Guo
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
| | - Yan Wang
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
| | - Yonggang Jiang
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
| | - Deyuan Zhang
- School of Mechanical Engineering and AutomationBeihang UniversityBeijing100191China
| | - Liran Ma
- State Key Laboratory of TribologyTsinghua UniversityBeijing100091China
| | - Jianbin Luo
- State Key Laboratory of TribologyTsinghua UniversityBeijing100091China
| | - Lei Jiang
- Laboratory of Bioinspired Smart Interface ScienceTechnical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China
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Kampowski T, Thiemann LL, Kürner L, Speck T, Poppinga S. Exploring the attachment of the Mediterranean medicinal leech ( Hirudo verbana) to porous substrates. J R Soc Interface 2020; 17:20200300. [PMID: 32673516 DOI: 10.1098/rsif.2020.0300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Haematophagous ectoparasites must ensure a reliable hold to their host during blood meals and, therefore, have evolved a broad spectrum of versatile and effective attachment mechanisms. The Mediterranean medicinal leech (Hirudo verbana), for example, uses suction on both smooth and textured air-tight substrates. However, preliminary studies showed that H. verbana is also capable of attaching itself to air-permeable substrates, where suction does not work. Using high-speed videography and mechanical tests, we comparatively investigated the attachment of H. verbana on both smooth and textured air-tight as well as on porous artificial substrates, also considering the influence of mucus on sucker surfaces. In general, the leech-specific locomotion cycle did not differ between the tested surfaces, and the leeches were able to reliably attach to both air-tight and porous substrates. From our results, we conclude that suction is presumably the primary attachment mechanism of H. verbana. However, secondary mechanisms such as mechanical interlocking with surface asperities and pores or capillary forces occurring at the interface between the mucus-covered suckers and the substratum are also employed. In any case, the rich repertoire of applicable attachment principles renders the organs of H. verbana functionally highly resilient.
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Affiliation(s)
- Tim Kampowski
- Plant Biomechanics Group (PBG), University of Freiburg, Botanic Garden, Schänzlestr. 1, 79104 Freiburg im Breisgau, Germany.,Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg im Breisgau, Germany
| | - Lara-Louise Thiemann
- Plant Biomechanics Group (PBG), University of Freiburg, Botanic Garden, Schänzlestr. 1, 79104 Freiburg im Breisgau, Germany
| | - Lukas Kürner
- Plant Biomechanics Group (PBG), University of Freiburg, Botanic Garden, Schänzlestr. 1, 79104 Freiburg im Breisgau, Germany
| | - Thomas Speck
- Plant Biomechanics Group (PBG), University of Freiburg, Botanic Garden, Schänzlestr. 1, 79104 Freiburg im Breisgau, Germany.,Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg im Breisgau, Germany.,Cluster of Excellence livMatS@ FIT - Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Simon Poppinga
- Plant Biomechanics Group (PBG), University of Freiburg, Botanic Garden, Schänzlestr. 1, 79104 Freiburg im Breisgau, Germany.,Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg im Breisgau, Germany
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Gong S, Yap LW, Zhu B, Cheng W. Multiscale Soft-Hard Interface Design for Flexible Hybrid Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1902278. [PMID: 31468635 DOI: 10.1002/adma.201902278] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/20/2019] [Indexed: 06/10/2023]
Abstract
Emerging next-generation soft electronics will require versatile properties functioning under mechanical compliance, which will involve the use of different types of materials. As a result, control over material interfaces (particularly soft/hard interfaces) has become crucial and is now attracting intensive worldwide research efforts. A series of material and structural interface designs has been devised to improve interfacial adhesion, preventing failure of electromechanical properties under mechanical deformation. Herein, different soft/hard interface design strategies at multiple length scales in the context of flexible hybrid electronics are reviewed. The crucial role of soft ligands and/or polymers in controlling the morphologies of active nanomaterials and stabilizing them is discussed, with a focus on understanding the soft/hard interface at the atomic/molecular scale. Larger nanoscopic and microscopic levels are also discussed, to scrutinize viable intrinsic and extrinsic interfacial designs with the purpose of promoting adhesion, stretchability, and durability. Furthermore, the macroscopic device/human interface as it relates to real-world applications is analyzed. Finally, a perspective on the current challenges and future opportunities in the development of truly seamlessly integrated soft wearable electronic systems is presented.
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Affiliation(s)
- Shu Gong
- Department of Chemical Engineering, Monash University, Clayton, Victoria, 3800, Australia
- The Melbourne Centre for Nanofabrication, Clayton, 151 Wellington Road, Victoria, 3800, Australia
| | - Lim Wei Yap
- Department of Chemical Engineering, Monash University, Clayton, Victoria, 3800, Australia
- The Melbourne Centre for Nanofabrication, Clayton, 151 Wellington Road, Victoria, 3800, Australia
| | - Bowen Zhu
- Department of Chemical Engineering, Monash University, Clayton, Victoria, 3800, Australia
- The Melbourne Centre for Nanofabrication, Clayton, 151 Wellington Road, Victoria, 3800, Australia
| | - Wenlong Cheng
- Department of Chemical Engineering, Monash University, Clayton, Victoria, 3800, Australia
- The Melbourne Centre for Nanofabrication, Clayton, 151 Wellington Road, Victoria, 3800, Australia
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Pillai R, Nordberg E, Riedel J, Schwarzkopf L. Nonlinear variation in clinging performance with surface roughness in geckos. Ecol Evol 2020; 10:2597-2607. [PMID: 32185005 PMCID: PMC7069281 DOI: 10.1002/ece3.6090] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/26/2022] Open
Abstract
Understanding the challenges faced by organisms moving within their environment is essential to comprehending the evolution of locomotor morphology and habitat use. Geckos have developed adhesive toe pads that enable exploitation of a wide range of microhabitats. These toe pads, and their adhesive mechanisms, have typically been studied using a range of artificial substrates, usually significantly smoother than those available in nature. Although these studies have been fundamental in understanding the mechanisms of attachment in geckos, it is unclear whether gecko attachment simply gradually declines with increased roughness as some researchers have suggested, or whether the interaction between the gekkotan adhesive system and surface roughness produces nonlinear relationships. To understand ecological challenges faced in their natural habitats, it is essential to use test surfaces that are more like surfaces used by geckos in nature. We tested gecko shear force (i.e., frictional force) generation as a measure of clinging performance on three artificial substrates. We selected substrates that exhibit microtopographies with peak-to-valley heights similar to those of substrates used in nature, to investigate performance on a range of smooth surfaces (glass), and fine-grained (fine sandpaper) to rough (coarse sandpaper). We found that shear force did not decline monotonically with roughness, but varied nonlinearly among substrates. Clinging performance was greater on glass and coarse sandpaper than on fine sandpaper, and clinging performance was not significantly different between glass and coarse sandpaper. Our results demonstrate that performance on different substrates varies, probably depending on the underlying mechanisms of the adhesive apparatus in geckos.
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Affiliation(s)
- Rishab Pillai
- College of Science and EngineeringJames Cook UniversityTownsvilleQLDAustralia
| | - Eric Nordberg
- College of Science and EngineeringJames Cook UniversityTownsvilleQLDAustralia
| | - Jendrian Riedel
- College of Science and EngineeringJames Cook UniversityTownsvilleQLDAustralia
| | - Lin Schwarzkopf
- College of Science and EngineeringJames Cook UniversityTownsvilleQLDAustralia
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Sandoval JA, Jadhav S, Quan H, Deheyn DD, Tolley MT. Reversible adhesion to rough surfaces both in and out of water, inspired by the clingfish suction disc. BIOINSPIRATION & BIOMIMETICS 2019; 14:066016. [PMID: 31553967 DOI: 10.1088/1748-3190/ab47d1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Adhesion is difficult to achieve on rough surfaces both in air and underwater. In nature, the northern clingfish (Gobiesox maeandricus) has evolved the impressive ability to adhere onto substrates of various shapes and roughnesses, while subject to strong intertidal surges. The suction disc of the clingfish relies on suction and friction to achieve and maintain adhesion. Inspired by this mechanism of attachment, we designed an artificial suction disc and evaluated its adhesive stress on rough surfaces and non-planar geometries. The artificial suction disc achieved adhesion strengths of 10.1 ± 0.3 kPa in air on surfaces of moderate roughness (grain size, 68 µm), and 14.3 ± 1.5 kPa underwater on coarse surfaces (grain size, 269 µm). By comparison, a commercially available suction cup failed to exhibit any significant adhesion in both scenarios. The roughly 2 g heavy clingfish-inspired suction discs gripped concave surfaces with small radii of curvature (12.5 mm) and supported payloads up to 0.7 kg. We correlated the effect of key bioinspired features (i.e. slits, a soft outer layer, and body geometry) to adhesion performance using contact visualization techniques and finite element analysis (FEA). The suction discs were then tested on a remotely operated vehicle (ROV) to demonstrate their utility in the soft manipulation of fragile objects.
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Affiliation(s)
- Jessica A Sandoval
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093, United States of America
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Chun S, Kim DW, Kim J, Pang C. A transparent, glue-free, skin-attachable graphene pressure sensor with micropillars for skin-elasticity measurement. NANOTECHNOLOGY 2019; 30:335501. [PMID: 31035268 DOI: 10.1088/1361-6528/ab1d99] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Strong peeling resistance and water-drainable properties on rough and wet skin surfaces are highly desirable for realizing wearable and skin-attachable electronic sensors. Here, we propose a transparent, sensitive, glue-free pressure sensor for skin electronics. To achieve a thin, light-weight, transparent, and stretchable sensor patch, we laminated a single-layer graphene film as a sensing element on a thin polymeric supporter of polydimethylsiloxane. By assembling the graphene layer with densely populated micropillars, the pressure sensor achieved 10 times the sensitivity of a similar sensor without micropillars in the low-pressure range (<6 kPa). We then employed hexagonal patterns inspired by the toe pads of a tree frog, giving the assembled patch sensor with strong peeling resistance under both dry and wet conditions on surfaces such as silicon (15.5 J cm-2 for dry and 11.6 J cm-2 for wet conditions) and pig skin (2.0 J cm-2 for dry and 1.4 J cm-2 for wet conditions) without contamination after detachment. Our layered sensor patch also demonstrated successful measurement of water-dependent skin elasticity with transparent, conformal, and residual-free attachment, suggesting a variety of cosmetic and medical applications.
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Affiliation(s)
- Sungwoo Chun
- Department SKKU Advanced Institute of Nanotechnology (SAINT) Sungkyunkwan University, Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea. School of Chemical Engineering, Sungkyunkwan University (SKKU), Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
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Meng F, Liu Q, Wang X, Tan D, Xue L, Barnes WJP. Tree frog adhesion biomimetics: opportunities for the development of new, smart adhesives that adhere under wet conditions. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20190131. [PMID: 31177956 PMCID: PMC6562351 DOI: 10.1098/rsta.2019.0131] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 05/31/2023]
Abstract
Enlarged adhesive toe pads on the tip of each digit allow tree frogs to climb smooth vertical and overhanging surfaces, and are effective in generating reversible adhesion under both dry and wet conditions. In this review, we discuss the complexities of the structure of tree frog toe pads in relation to their function and review their biomimetic potential. Of particular importance are the (largely) hexagonal epithelial cells surrounded by deep channels that cover the surface of each toe pad and the array of nanopillars on their surface. Fluid secreted by the pads covers the surface of each pad, so the pads adhere by wet adhesion, involving both capillarity and viscosity-dependent forces. The fabrication and testing of toe pad mimics are challenging, but valuable both for testing hypotheses concerning tree frog toe pad function and for developing toe pad mimics. Initial mimics involved the fabrication of hexagonal pillars mimicking the toe pad epithelial structure. More recent ones additionally replicate the nanostructures on their surface. Finally we describe some of the biomimetic applications that have been developed from toe pad mimics, which include both bioinspired adhesives and friction-generating devices. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology (part 2)'.
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Affiliation(s)
- Fandong Meng
- School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan, People's Republic of China
| | - Quan Liu
- School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan, People's Republic of China
| | - Xin Wang
- School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan, People's Republic of China
| | - Di Tan
- School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan, People's Republic of China
| | - Longjian Xue
- School of Power and Mechanical Engineering, Wuhan University, South Donghu Road 8, Wuhan, People's Republic of China
| | - W. Jon. P. Barnes
- Centre for Cell Engineering, University of Glasgow, Joseph Black Building, Glasgow G12 8QQ, UK
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Langowski JKA, Singla S, Nyarko A, Schipper H, van den Berg FT, Kaur S, Astley HC, Gussekloo SWS, Dhinojwala A, van Leeuwen JL. Comparative and functional analysis of the digital mucus glands and secretions of tree frogs. Front Zool 2019; 16:19. [PMID: 31210775 PMCID: PMC6563374 DOI: 10.1186/s12983-019-0315-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022] Open
Abstract
Background Mucus and mucus glands are important features of the amphibian cutis. In tree frogs, the mucus glands and their secretions are crucial components of the adhesive digital pads of these animals. Despite a variety of hypothesised functions of these components in tree frog attachment, the functional morphology of the digital mucus glands and the chemistry of the digital mucus are barely known. Here, we use an interdisciplinary comparative approach to analyse these components, and discuss their roles in tree frog attachment. Results Using synchrotron micro-computer-tomography, we discovered in the arboreal frog Hyla cinerea that the ventral digital mucus glands differ in their morphology from regular anuran mucus glands and form a subdermal gland cluster. We show the presence of this gland cluster also in several other—not exclusively arboreal—anuran families. Using cryo-histochemistry as well as infrared and sum frequency generation spectroscopy on the mucus of two arboreal (H. cinerea and Osteopilus septentrionalis) and of two terrestrial, non-climbing frog species (Pyxicephalus adspersus and Ceratophrys cranwelli), we find neutral and acidic polysaccharides, and indications for proteinaceous and lipid-like mucus components. The mucus chemistry varies only little between dorsal and ventral digital mucus in H. cinerea, ventral digital and abdominal mucus in H. cinerea and O. septentrionalis, and between the ventral abdominal mucus of all four studied species. Conclusions The presence of a digital mucus gland cluster in various anuran families, as well as the absence of differences in the mucus chemistry between arboreal and non-arboreal frog species indicate an adaptation towards generic functional requirements as well as to attachment-related requirements. Overall, this study contributes to the understanding of the role of glands and their secretions in tree frog attachment and in bioadhesion in general, as well as the evolution of anurans. Electronic supplementary material The online version of this article (10.1186/s12983-019-0315-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Julian K A Langowski
- 1Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Saranshu Singla
- 2Department of Polymer Science, The University of Akron, 170 University Ave, Akron, Ohio 44325-3909 USA
| | - Alex Nyarko
- 2Department of Polymer Science, The University of Akron, 170 University Ave, Akron, Ohio 44325-3909 USA
| | - Henk Schipper
- 1Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Frank T van den Berg
- 1Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Sukhmanjot Kaur
- 2Department of Polymer Science, The University of Akron, 170 University Ave, Akron, Ohio 44325-3909 USA
| | - Henry C Astley
- 3Biomimicry Research & Innovation Center, Departments of Biology and Polymer Science, The University of Akron, 235 Carroll St., Akron, Ohio 44325-3908 USA
| | - Sander W S Gussekloo
- 1Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
| | - Ali Dhinojwala
- 2Department of Polymer Science, The University of Akron, 170 University Ave, Akron, Ohio 44325-3909 USA
| | - Johan L van Leeuwen
- 1Experimental Zoology Group, Department of Animal Sciences, Wageningen University & Research, De Elst 1, Wageningen, 6708 WD The Netherlands
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Young JW, Hyde A, German R. Ontogeny of intrinsic digit proportions in laboratory rats (Rattus norvegicus): a test of the grasping theory of primate hand and foot growth. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Jesse W Young
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, OH, USA
- Musculoskeletal Biology Research Focus Area, NEOMED, Rootstown, OH, USA
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
| | - Alexander Hyde
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, OH, USA
| | - Rebecca German
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University (NEOMED), Rootstown, OH, USA
- Musculoskeletal Biology Research Focus Area, NEOMED, Rootstown, OH, USA
- School of Biomedical Sciences, Kent State University, Kent, OH, USA
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