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Li W, Zhou R, Ouyang Y, Guan Q, Shen Y, Saiz E, Li M, Hou X. Harnessing Biomimicry for Controlled Adhesion on Material Surfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401859. [PMID: 39031996 DOI: 10.1002/smll.202401859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/25/2024] [Indexed: 07/22/2024]
Abstract
Nature serves as an abundant wellspring of inspiration for crafting innovative adhesive materials. Extensive research is conducted on various complex forms of biological attachment, such as geckos, tree frogs, octopuses, and mussels. However, significant obstacles still exist in developing adhesive materials that truly replicate the behaviors and functionalities observed in living organisms. Here, an overview of biological organs, structures, and adhesive secretions endowed with adhesion capabilities, delving into the intricate relationship between their morphology and function, and potential for biomimicry are provided. First, the design principles and mechanisms of adhesion behavior and individual organ morphology in nature are summarized from the perspective of structural and size constraints. Subsequently, the value of engineered and bioinspired adhesive materials through selective application cases in practical fields is emphasized. Then, a forward-looking gaze on the conceivable challenges and associated opportunities in harnessing biomimetic strategies and biological materials for advancing adhesive material innovation is highlighted and cast.
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Affiliation(s)
- Weijun Li
- School of Materials Science and Engineering, Xiamen University of Technology, Xiamen, 361024, China
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Ruini Zhou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Yirui Ouyang
- College of Materials, Xiamen University, Xiamen, 361005, China
| | - Qingwen Guan
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Yigang Shen
- College of Engineering, Zhejiang Normal University, Jinhua, 321004, China
| | - Eduardo Saiz
- Centre of Advanced Structural Ceramics, Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - Ming Li
- Centre of Advanced Structural Ceramics, Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - Xu Hou
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
- Department of Physics, Research Institute for Biomimetics and Soft Matter, Fujian Provincial Key Laboratory for Soft Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen, 361102, China
- Engineering Research Center of Electrochemical Technologies of Ministry of Education, Xiamen University, Xiamen, 361005, China
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2
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Lai J, Wang X, Zhao Q, Zhang C, Gong T, He L, Wang Z, Xia H. 3D Printing Self-Healing and Self-Adhesive Elastomers for Wearable Electronics in Amphibious Environments. ACS APPLIED MATERIALS & INTERFACES 2024; 16:16880-16892. [PMID: 38506556 DOI: 10.1021/acsami.4c01568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
To meet the demands of challenging usage scenarios, there is an increasing need for flexible electronic skins that can operate properly not only in terrestrial environments but also extend to complex aquatic conditions. In this study, we develop an elastomer by incorporating dynamic urea bonds and hydrogen bonds into the polydimethylsiloxane backbone, which exhibits excellent autonomous self-healing and reversible adhesive performance in both dry and wet environments. A multifunctional flexible sensor with excellent sensing stability, amphibious self-healing capacity, and amphibious self-adhesive performance is fabricated through solvent-free 3D printing. The sensor has a high sensing sensitivity (GF = 45.1) and a low strain response threshold (0.25%) and can be used to detect small human movements and physiological activities, such as muscle movement, joint movement, respiration, and heartbeat. The wireless wearable sensing system assembled by coupling this device with a bluetooth transmission system is suitable for monitoring strenuous human movement in amphibious environments, such as playing basketball, cycling, running (terrestrial environments), and swimming (aquatic environments). The design strategy provides insights into enhancing the self-healing and self-adhesive properties of soft materials and promises a prospective avenue for fabricating flexible electronic skin that can work properly in amphibious environments.
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Affiliation(s)
- Jialiang Lai
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Xiaorong Wang
- School of Petrochemical Engineering, Liaoning Petrochemical University, Fushun, Liaoning 113001, China
| | - Qifan Zhao
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Chun Zhang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Tao Gong
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Lirong He
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Zhanhua Wang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
| | - Hesheng Xia
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, China
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Liu Y, Wang H, Li J, Li P, Li S. Gecko-Inspired Controllable Adhesive: Structure, Fabrication, and Application. Biomimetics (Basel) 2024; 9:149. [PMID: 38534834 DOI: 10.3390/biomimetics9030149] [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: 01/31/2024] [Revised: 02/18/2024] [Accepted: 02/24/2024] [Indexed: 03/28/2024] Open
Abstract
The gecko can achieve flexible climbing on various vertical walls and even ceilings, which is closely related to its unique foot adhesion system. In the past two decades, the mechanism of the gecko adhesion system has been studied in-depth, and a verity of gecko-inspired adhesives have been proposed. In addition to its strong adhesion, its easy detachment is also the key to achieving efficient climbing locomotion for geckos. A similar controllable adhesion characteristic is also key to the research into artificial gecko-inspired adhesives. In this paper, the structures, fabrication methods, and applications of gecko-inspired controllable adhesives are summarized for future reference in adhesive development. Firstly, the controllable adhesion mechanism of geckos is introduced. Then, the control mechanism, adhesion performance, and preparation methods of gecko-inspired controllable adhesives are described. Subsequently, various successful applications of gecko-inspired controllable adhesives are presented. Finally, future challenges and opportunities to develop gecko-inspired controllable adhesive are presented.
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Affiliation(s)
- Yanwei Liu
- Key Laboratory of NC Machine Tools and Integrated Manufacturing Equipment of the Ministry of Education, Xi'an University of Technology, Xi'an 710048, China
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
| | - Hao Wang
- Key Laboratory of NC Machine Tools and Integrated Manufacturing Equipment of the Ministry of Education, Xi'an University of Technology, Xi'an 710048, China
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
| | - Jiangchao Li
- Key Laboratory of NC Machine Tools and Integrated Manufacturing Equipment of the Ministry of Education, Xi'an University of Technology, Xi'an 710048, China
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
| | - Pengyang Li
- Key Laboratory of NC Machine Tools and Integrated Manufacturing Equipment of the Ministry of Education, Xi'an University of Technology, Xi'an 710048, China
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
| | - Shujuan Li
- Key Laboratory of NC Machine Tools and Integrated Manufacturing Equipment of the Ministry of Education, Xi'an University of Technology, Xi'an 710048, China
- School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China
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Li J, Yin F, Tian Y. Biomimetic Structure and Surface for Grasping Tasks. Biomimetics (Basel) 2024; 9:144. [PMID: 38534829 DOI: 10.3390/biomimetics9030144] [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: 01/20/2024] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 03/28/2024] Open
Abstract
Under water, on land, or in the air, creatures use a variety of grasping methods to hunt, avoid predators, or carry food. Numerous studies have been conducted to construct a bionic surface for grasping tasks. This paper reviews the typical biomimetic structures and surfaces (wedge-shaped surface, suction cup surface and thorn claw surface) for grasping scenarios. Initially, progress in gecko-inspired wedge-shaped adhesive surfaces is reviewed, encompassing the underlying mechanisms that involve tuning the contact area and peeling behavior. The applications of grippers utilizing this adhesive technology are also discussed. Subsequently, the suction force mechanisms and applications of surfaces inspired by octopus and remora suction cups are outlined. Moreover, this paper introduces the applications of robots incorporating the principles of beetle-inspired and bird-inspired thorn claw structures. Lastly, inspired by remoras' adhesive discs, a composite biomimetic adhesive surface is proposed. It integrates features from wedge-shaped, suction cup, and claw thorn surfaces, potentially surpassing the adaptability of basic bioinspired surfaces. This surface construction method offers a potential avenue to enhance adhesion capabilities with superior adaptability to surface roughness and curvature.
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Affiliation(s)
- Jingyang Li
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Fujie Yin
- Xingjian College, Tsinghua University, Beijing 100084, China
| | - Yu Tian
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
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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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Lyashenko IA, Pham TH, Popov VL. Effect of Indentation Depth on Friction Coefficient in Adhesive Contacts: Experiment and Simulation. Biomimetics (Basel) 2024; 9:52. [PMID: 38248626 PMCID: PMC10813419 DOI: 10.3390/biomimetics9010052] [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: 11/29/2023] [Revised: 12/31/2023] [Accepted: 01/10/2024] [Indexed: 01/23/2024] Open
Abstract
The quasi-static regime of friction between a rigid steel indenter and a soft elastomer with high adhesion is studied experimentally. An analysis of the formally calculated dependencies of a friction coefficient on an external load (normal force) shows that the friction coefficient monotonically decreases with an increase in the load, following a power law relationship. Over the entire range of contact loads, a friction mode is realized in which constant shear stresses are maintained in the tangential contact, which corresponds to the "adhesive" friction mode. In this mode, Amonton's law is inapplicable, and the friction coefficient loses its original meaning. Some classical works, which show the existence of a transition between "adhesive" and "normal" friction, were analyzed. It is shown that, in fact, there is no such transition. A computer simulation of the indentation process was carried out within the framework of the boundary element method, which confirmed the experimental results.
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Affiliation(s)
- Iakov A. Lyashenko
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany; (T.H.P.); (V.L.P.)
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Sivasundarampillai J, Youssef L, Priemel T, Mikulin S, Eren ED, Zaslansky P, Jehle F, Harrington MJ. A strong quick-release biointerface in mussels mediated by serotonergic cilia-based adhesion. Science 2023; 382:829-834. [PMID: 37972188 DOI: 10.1126/science.adi7401] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
The mussel byssus stem provides a strong and compact mechanically mismatched biointerface between living tissue and a nonliving biopolymer. Yet, in a poorly understood process, mussels can simply jettison their entire byssus, rebuilding a new one in just hours. We characterized the structure and composition of the byssus biointerface using histology, confocal Raman mapping, phase contrast-enhanced microcomputed tomography, and advanced electron microscopy, revealing a sophisticated junction consisting of abiotic biopolymer sheets interdigitated between living extracellular matrix. The sheet surfaces are in intimate adhesive contact with billions of motile epithelial cilia that control biointerface strength and stem release through their collective movement, which is regulated neurochemically. We posit that this may involve a complex sensory pathway by which sessile mussels respond to environmental stresses to release and relocate.
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Affiliation(s)
- Jenaes Sivasundarampillai
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Lucia Youssef
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Tobias Priemel
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Sydney Mikulin
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - E Deniz Eren
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Paul Zaslansky
- Department for Operative, Preventive and Pediatric Dentistry, Charité-Universitätsmedizin Berlin, Berlin 14197, Germany
| | - Franziska Jehle
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Matthew J Harrington
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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Lyashenko IA, Popov VL, Borysiuk V. Indentation and Detachment in Adhesive Contacts between Soft Elastomer and Rigid Indenter at Simultaneous Motion in Normal and Tangential Direction: Experiments and Simulations. Biomimetics (Basel) 2023; 8:477. [PMID: 37887608 PMCID: PMC10603904 DOI: 10.3390/biomimetics8060477] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/28/2023] Open
Abstract
In reported experiments, a steel indenter was pressed into a soft elastomer layer under varying inclination angles and subsequently was detached under various inclination angles too. The processes of indentation and detachment were recorded with a video camera, and the time dependences of the normal and tangential components of the contact force and the contact area, as well as the average contact pressure and average tangential stresses, were measured as functions of the inclination angle. Based on experimental results, a simple theoretical model of the indentation process is proposed, in which tangential and normal contacts are considered independently. Both experimental and theoretical results show that at small indentation angles (when the direction of motion is close to tangential), a mode with elastomer slippage relative to the indenter is observed, which leads to complex dynamic processes-the rearrangement of the contact boundary and the propagation of elastic waves (similar to Schallamach waves). If the angle is close to the normal angle, there is no slipping in the contact plane during the entire indentation (detachment) phase.
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Affiliation(s)
- Iakov A. Lyashenko
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany; (V.L.P.); (V.B.)
- Department of Applied Mathematics and Complex Systems Modeling, Faculty of Electronics and Information Technology, Sumy State University, 40007 Sumy, Ukraine
| | - Valentin L. Popov
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany; (V.L.P.); (V.B.)
| | - Vadym Borysiuk
- Department of System Dynamics and Friction Physics, Institute of Mechanics, Technische Universität Berlin, 10623 Berlin, Germany; (V.L.P.); (V.B.)
- Department of Nanoelectronics and Surface Modification, Faculty of Electronics and Information Technology, Sumy State University, 40007 Sumy, Ukraine
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Tan L, Chen Y, Fu W, Tian J, Wang Y, Li X, Zhou Y, Xia S, Liang M, Zou H. Bioinspired Microadhesives with Greatly Enhanced Reversible Adhesion Fabricated by Synthesized Silicone Elastomer with Increasing Phenyl Contents. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13068-13075. [PMID: 37678181 DOI: 10.1021/acs.langmuir.3c01382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
We present a facile chemical method for fabricating bioinspired microadhesives with significant improved reversible adhesion strength. Four kinds of polysiloxane with gradient varying phenyl contents were synthesized and used to fabricate microadhesives. The chemical structures and mechanical properties, as well as surface properties of the four microadhesives, were confirmed and characterized by ATR-FTIR, DSC, XPS, low-field NMR, tensile tests, and SEM, respectively. The macroadhesion test results revealed that phenyl contents showed remarkable and positive impacts on the macroadhesion performance of microadhesives. The pull-off adhesion strength of microadhesives with 90% phenyl content (0.851 N/cm2) was nearly 300% higher than that of pure PDMS (0.309 N/cm2). The macroadhesion mechanism analysis demonstrates that a larger bulk energy dissipation caused by massive π-π interaction, as well as the hydrophobic interaction and van der Waals forces at the interface synergistically resulted in a significant enhancement of the adhesion performance. Our results demonstrate the remarkable impact of chemical structures on the adhesion of microadhesives, and it is conducive to the further improvement of adhesion properties of bioinspired microadhesives.
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Affiliation(s)
- Lei Tan
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yukun Chen
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Wenxin Fu
- Key Laboratory of Science and Technology on High-tech Polymer Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinfeng Tian
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yuan Wang
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Xiaohui Li
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Yilin Zhou
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Shuang Xia
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Mei Liang
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
| | - Huawei Zou
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
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Materzok T, Eslami H, Gorb SN, Müller-Plathe F. Understanding Humidity-Enhanced Adhesion of Geckos: Deep Neural Network-Assisted Multi-Scale Molecular Modeling. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206085. [PMID: 36707414 DOI: 10.1002/smll.202206085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/06/2022] [Indexed: 06/02/2023]
Abstract
A higher relative humidity leads to an increased sticking power of gecko feet to surfaces. The molecular mechanism responsible for this increase, however, is not clear. Capillary forces, water mediating keratin-surface contacts and water-induced softening of the keratin are proposed as candidates. In previous work, strong evidence for water mediation is found but indirect effects via increased flexibility are not completely ruled out. This article studies the latter hypothesis by a bottom-up coarse-grained mesoscale model of an entire gecko spatula designed without explicit water particles, so that capillary action and water-mediation are excluded. The elasticity of this model is adjusted with a deep neural network to atomistic elastic constants, including water at different concentrations. Our results show clearly that on nanoscopic flat surfaces, the softening of keratin by water uptake cannot nearly account for the experimentally observed increase in gecko sticking power. Here, the dominant mechanism is the mediation of keratin-surface contacts by intervening water molecules. This mechanism remains important on nanostructured surfaces. Here, however, a water-induced increase of the keratin flexibility may enable the spatula to follow surface features smaller than itself and thereby increase the number of contacts with the surface. This leads to an appreciable but not dominant contribution to the humidity-increased adhesion. Recently, by atomistic grand-canonical molecular dynamics simulation, the room-temperature isotherm is obtained for the sorption of water into gecko keratin, to the authors' knowledge, the first such relation for any beta-keratin. In this work, it relates the equilibrium water content of the keratin to the ambient relative humidity.
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Affiliation(s)
- Tobias Materzok
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Hossein Eslami
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
- Department of Chemistry, Colleges of Sciences, Persian Gulf University, Boushehr, 75168, Iran
| | - Stanislav N Gorb
- Zoological Institute Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118, Kiel, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
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Wang D, Hu H, Li S, Tian H, Fan W, Li X, Chen X, Taylor AC, Shao J. Sensing-triggered stiffness-tunable smart adhesives. SCIENCE ADVANCES 2023; 9:eadf4051. [PMID: 36921055 PMCID: PMC10017039 DOI: 10.1126/sciadv.adf4051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Artificial dry adhesives have exhibited great potential in the field of robotics. However, there is still a wide gap between bioinspired adhesives and living tissues, especially regarding the surface adaptability and switching ability of attachment/detachment. Here, we propose a sensing-triggered stiffness-tunable smart adhesive material, combining the functions of muscle tissues and sensing nerves rather than traditional biomimetic adhesive strategy that only focuses on structural geometry. Authorized by real-time perception of the interface contact state, conformal contact, shape locking, and active releasing are achieved by adjusting the stiffness based on the magnetorheological effect. Because of the fast switching of the magnetic field, a millisecond-level attachment/detachment response is successfully achieved, breaking the bottleneck of adhesive materials for high-speed manipulation. The innovative design can be applied to any toe's surface structure, opening up a previously unknown avenue for the development of adhesive materials.
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Affiliation(s)
- Duorui Wang
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Hong Hu
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Shuai Li
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Hongmiao Tian
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Wei Fan
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Xiangming Li
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Xiaoliang Chen
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Ambrose C. Taylor
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Jinyou Shao
- Micro-and Nano-Technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
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Zhang D, Xu J, Liu X, Zhang Q, Cong Q, Chen T, Liu C. Advanced Bionic Attachment Equipment Inspired by the Attachment Performance of Aquatic Organisms: A Review. Biomimetics (Basel) 2023; 8:biomimetics8010085. [PMID: 36810416 PMCID: PMC9944885 DOI: 10.3390/biomimetics8010085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/11/2023] [Accepted: 02/13/2023] [Indexed: 02/19/2023] Open
Abstract
In nature, aquatic organisms have evolved various attachment systems, and their attachment ability has become a specific and mysterious survival skill for them. Therefore, it is significant to study and use their unique attachment surfaces and outstanding attachment characteristics for reference and develop new attachment equipment with excellent performance. Based on this, in this review, the unique non-smooth surface morphologies of their suction cups are classified and the key roles of these special surface morphologies in the attachment process are introduced in detail. The recent research on the attachment capacity of aquatic suction cups and other related attachment studies are described. Emphatically, the research progress of advanced bionic attachment equipment and technology in recent years, including attachment robots, flexible grasping manipulators, suction cup accessories, micro-suction cup patches, etc., is summarized. Finally, the existing problems and challenges in the field of biomimetic attachment are analyzed, and the focus and direction of biomimetic attachment research in the future are pointed out.
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Affiliation(s)
- Dexue Zhang
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China
- Shandong Academy of Agricultural Machinery Sciences, Jinan 250100, China
| | - Jin Xu
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China
| | - Xuefeng Liu
- Shandong Academy of Agricultural Machinery Sciences, Jinan 250100, China
- Institute of Modern Agriculture on Yellow River Delta, Shandong Academy of Agricultural Sciences, Dongying 257300, China
| | - Qifeng Zhang
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China
- Shandong Academy of Agricultural Machinery Sciences, Jinan 250100, China
| | - Qian Cong
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China
- State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022, China
- Correspondence: (Q.C.); (T.C.)
| | - Tingkun Chen
- Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China
- Correspondence: (Q.C.); (T.C.)
| | - Chaozong Liu
- Institute of Orthopaedic & Musculoskeletal Science, University College London, London HA7 4LP, UK
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13
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Alibardi L. Ultrastructural observations suggest that lipid material of lizard digital pads derives from degenerating cells in the inter‐scale region. ACTA ZOOL-STOCKHOLM 2023. [DOI: 10.1111/azo.12458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Lorenzo Alibardi
- Department of Biology University of Bologna Bologna Italy
- Comparative Histolab Padova Bologna Italy
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14
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Gecko-Inspired Adhesive Mechanisms and Adhesives for Robots—A Review. ROBOTICS 2022. [DOI: 10.3390/robotics11060143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Small living organisms such as lizards possess naturally built functional surface textures that enable them to walk or climb on versatile surface topographies. Bio-mimicking the surface characteristics of these geckos has enormous potential to improve the accessibility of modern robotics. Therefore, gecko-inspired adhesives have significant industrial applications, including robotic endoscopy, bio-medical cleaning, medical bandage tapes, rock climbing adhesives, tissue adhesives, etc. As a result, synthetic adhesives have been developed by researchers, in addition to dry fibrillary adhesives, elastomeric adhesives, electrostatic adhesives, and thermoplastic adhesives. All these adhesives represent significant contributions towards robotic grippers and gloves, depending on the nature of the application. However, these adhesives often exhibit limitations in the form of fouling, wear, and tear, which restrict their functionalities and load-carrying capabilities in the natural environment. Therefore, it is essential to summarize the state of the art attributes of contemporary studies to extend the ongoing work in this field. This review summarizes different adhesion mechanisms involving gecko-inspired adhesives and attempts to explain the parameters and limitations which have impacts on adhesion. Additionally, different novel adhesive fabrication techniques such as replica molding, 3D direct laser writing, dip transfer processing, fused deposition modeling, and digital light processing are encapsulated.
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15
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Materzok T, Canestraight A, Gorb SN, Müller-Plathe F. How Does Gecko Keratin Stick to Hydrophilic and Hydrophobic Surfaces in the Presence and Absence of Water? An Atomistic Molecular Dynamics Investigation. ACS NANO 2022; 16:19261-19270. [PMID: 36256850 DOI: 10.1021/acsnano.2c08627] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We developed a united-atom model of gecko keratin to investigate the influence of electrostatic and van der Waals contributions to gecko adhesion in scenarios representing gecko's natural habitats. The keratin model assumes that only intrinsically disordered regions directly contact the surface. Contact angles of two generic substrate surfaces that we created match those previously used in AFM experiments on gecko adhesion. Force probe molecular dynamics simulations pulling the keratin from the surface show that the pull-off force increases with increased water content and is inversely related to the water contact angle of the surface. This matches experimental trends. We investigated the number and charge density of keratin and water at the surface, confirming a water-mediating effect and are able to show that keratin folds polar groups to the hydrophilic surface. We decomposed energetic contributions during pull-off, and our computational model shows that in contrast to popular hypotheses, long-range electrostatic interactions determine much of the pull-off process. The contribution of electrostatics to adhesion may be in the order of the van der Waals contributions.
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Affiliation(s)
- Tobias Materzok
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany
| | - Annabelle Canestraight
- Department of Chemical Engineering, University of California Santa Barbara, 3357 Engrg II UCSB, Santa Barbara, California 93106, United States
| | - Stanislav N Gorb
- Zoological Institute Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118 Kiel, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, D-64287 Darmstadt, Germany
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16
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Xia S, Chen Y, Fu W, Tian J, Zhou Y, Sun Y, Cao R, Zou H, Liang M. A humidity-resistant bio-inspired microfibrillar adhesive fabricated using a phenyl-rich polysiloxane elastomer for reliable skin patches. J Mater Chem B 2022; 10:9179-9187. [PMID: 36341761 DOI: 10.1039/d2tb01955h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Steady adhesion under varying humidity conditions is fundamentally challenging due to the barrier of interfacial water molecules. Here, we demonstrate a humidity-resistant gecko-inspired microfibrillar adhesive fabricated by using a specific phenyl-rich polysiloxane. In contrast with the great decline of macroadhesion with increasing humidity for the typical polydimethylsiloxane (PDMS) microfibrillar adhesives, strong macroadhesion of a microfibrillar adhesive fabricated using synthetic phenyl-rich polysiloxane maintains adhesion well across a wide relative humidity range (1% to 95%). Moreover, the pull-off strength is increased by 500% compared to that of phenyl-absent PDMS microfibrillar adhesives at extremely high humidity. Mechanism analysis demonstrates that the synergistic interplay of strong interfacial hydrophobicity leading to dry contact and bulk energy dissipation through massive aromatic π-π interactions contributes greatly to the reliable and strong humidity macroadhesion. The present results provide a better understanding of humidity macroadhesion as well as application potential for microfibrillar adhesives, which are proven to be reliable skin adhesive patches for long-term health-care that have to be exposed to varying humidity conditions of the skin surface.
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Affiliation(s)
- Shuang Xia
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Yukun Chen
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Wenxin Fu
- Key Laboratory of Science and Technology on High-tech Polymer Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jinfeng Tian
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Yilin Zhou
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Yini Sun
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Ruoxuan Cao
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Huawei Zou
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
| | - Mei Liang
- The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China.
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17
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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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18
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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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19
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Shin J, Lee JG, Lee G, Pikhitsa PV, Kim SM, Choi M, Choi YW. Reversible Wrinkling Surfaces for Enhanced Grip on Wet/Dry Conditions. ACS APPLIED MATERIALS & INTERFACES 2022; 14:48311-48320. [PMID: 36253341 DOI: 10.1021/acsami.2c15653] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Friction is important in material design for robotic systems that need to perform tasks regardless of environmental changes. Generally, robotic systems lose their friction in wet environments and fail to accomplish their tasks. Despite the significance of maintaining friction in dry and wet environments, it is still challenging. Here, we report a smart switching surface, which helps to complete missions in both wet and dry environments. Inspired by the reversible wrinkling mechanism of a human finger, the surface reversibly generates and removes wrinkles to adapt to both environments using volume-changing characteristics of the Nafion film. The switchable surfaces with manipulated wrinkle morphologies via patterns of diverse densities, sizes, and shapes induce a relationship between the wrinkle morphologies and friction: wrinkles on denser and smaller hexagonal patterns generate six times more friction than non-switching flat surfaces in wet environments and a similar amount of friction to the flat surfaces in dry environments. In addition, the wrinkle morphologies according to the patterns are predicted through numerical simulation, which is in good agreement with experimental results. This work presents potential applications in robotic systems that are required to perform in and out of water and paves the way for further understanding of wrinkling dynamics, manipulation, and evolutionary function in skin.
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Affiliation(s)
- Jooyeon Shin
- Global Frontier Center for Multiscale Energy Systems, Seoul National University, Seoul08826, Korea
- Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul08826, Korea
| | - Jong-Gu Lee
- Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul08826, Korea
| | - Gunhee Lee
- Department of Environment Machinery, Korea Institute of Machinery & Materials, Daejeon34103, Korea
| | - Peter V Pikhitsa
- Global Frontier Center for Multiscale Energy Systems, Seoul National University, Seoul08826, Korea
| | - Sang Moon Kim
- Department of Mechanical Engineering, Incheon National University, Incheon22012, Korea
| | - Mansoo Choi
- Global Frontier Center for Multiscale Energy Systems, Seoul National University, Seoul08826, Korea
- Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul08826, Korea
| | - Yong Whan Choi
- Division of Mechanical Convergence Engineering, College of MICT Convergence Engineering, Silla University, Busan46958, Korea
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20
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Elder T, Croll AB. Roughness tolerant pressure sensitive adhesives made of sticky crumpled sheets. SOFT MATTER 2022; 18:7866-7876. [PMID: 36205147 DOI: 10.1039/d2sm00858k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
If an adhesive is meant to be temporary, roughness often poses a challenge for design. An adhesive could be made soft so that it can deform and increase surface contact but a softer material will in general hold a smaller load. Bioinspired adhesives, made with numerous microscale posts, show promise as roughness tolerant adhesives but are complicated to fabricate. In this work, we show how thin polymer sheets, when crumpled into a roughly spherical shape, form a very simple and roughness tolerant adhesive system. We use micro and macro-scale experiments to measure adhesion forces between various substrates and crumpled polydimethylsiloxane sheets. We find the force-displacement curves resemble probe-tack experiments of traditional pressure sensitive adhesives and that moderate tensile forces are required to initiate interfacial failure. Notably, we see that sticky crumples often perform better on long wavelength roughness than they do on smooth substrates. In order to improve the peak pull-off forces, we create a sticky crumple from a thin sheet of a glassy polymer, polycarbonate, coated with an adhesive layer. This elasto-plastic sticky crumple achieves high pull-off forces even on the rough surface of a landscaping brick.
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Affiliation(s)
- Theresa Elder
- Materials and Nanotechnology, North Dakota State University, Fargo, USA
| | - Andrew B Croll
- Materials and Nanotechnology, North Dakota State University, Fargo, USA
- Department of Physics, North Dakota State University, Fargo, USA.
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21
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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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22
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Materzok T, De Boer D, Gorb S, Müller-Plathe F. Gecko Adhesion on Flat and Rough Surfaces: Simulations with a Multi-Scale Molecular Model. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2201674. [PMID: 35927024 DOI: 10.1002/smll.202201674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 07/07/2022] [Indexed: 06/15/2023]
Abstract
A multiscale modeling approach is used to develop a particle-based mesoscale gecko spatula model that is able to link atomistic simulations and mesoscale (0.44 µm) simulations. It is used to study the detachment of spatulae from flat as well as nanostructured surfaces. The spatula model is based on microscopical information about spatulae structure and on atomistic molecular simulation results. Target properties for the coarse-graining result from a united-atom model of gecko keratin in periodic boundary conditions (PBC), previously developed by the authors. Pull-off forces necessary to detach gecko keratin under 2D PBC parallel to the surface are previously overestimated when only a small region of a spatula is examined. It is shown here that this is due to the restricted geometry (i.e., missing peel-off mode) and not model parameters. The spatula model peels off when pulled away from a surface, both in the molecular picture of the pull-off process and in the force-extension curve of non-equilibrium simulations mimicking single-spatula detachment studied with atomic force microscopy equipment. The force field and spatula model can reproduce experimental pull-off forces. Inspired by experimental results, the underlying mechanism that causes pull-off forces to be at a minimum on surfaces of varying roughnesses is also investigated. A clear sigmoidal increase in the pull-off force of spatulae with surface roughness shows that adhesion is determined by the ratio between spatula pad area and the area between surface peaks. Experiments showed a correlation with root-mean-square roughness of the surface, but the results of this work indicate that this is not a causality but depends on the area accessible.
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Affiliation(s)
- Tobias Materzok
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Danna De Boer
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
| | - Stanislav Gorb
- Zoological Institute Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118, Kiel, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287, Darmstadt, Germany
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23
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Khani M, Materzok T, Eslami H, Gorb S, Müller-Plathe F. Water uptake by gecko β-keratin and the influence of relative humidity on its mechanical and volumetric properties. J R Soc Interface 2022; 19:20220372. [PMID: 36128704 PMCID: PMC9490342 DOI: 10.1098/rsif.2022.0372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 08/31/2022] [Indexed: 11/12/2022] Open
Abstract
Grand canonical ensemble molecular dynamics simulations are done to calculate the water content of gecko β-keratin as a function of relative humidity (RH). For comparison, we experimentally measured the water uptake of scales of the skin of cobra Naja nigricollis. The calculated sigmoidal sorption isotherm is in good agreement with experiment. To examine the softening effect of water on gecko keratin, we have calculated the mechanical properties of dry and wet keratin samples, and we have established relations between the mechanical properties and the RH. We found that a higher RH causes a decrease in the Young's modulus, the yield stress, the yield strain, the stress at failure and an increase in the strain at failure of the gecko keratin. At low RHs (less than 80%), the change in the mechanical properties is small, with most of the changes occurring at higher RHs. The changes in the macroscopic properties of the keratin are explained by the action of sorbed water on the molecular scale. It causes keratin to swell, thereby increasing the distances between amino acids. This has a weakening effect on amino acid interactions and softens the keratin material. The effect is more pronounced at higher RHs.
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Affiliation(s)
- Marzieh Khani
- Department of Chemistry, College of Sciences, Persian Gulf University, Boushehr 75168, Iran
| | - Tobias Materzok
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, 64287 Darmstadt, Germany
| | - Hossein Eslami
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, 64287 Darmstadt, Germany
- Department of Chemistry, College of Sciences, Persian Gulf University, Boushehr 75168, Iran
| | - Stanislav Gorb
- Zoological Institute, Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, 64287 Darmstadt, Germany
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24
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Shi W, Cheng X, Cheng K. Gecko-Inspired Adhesives with Asymmetrically Tilting-Oriented Micropillars. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8890-8898. [PMID: 35830463 DOI: 10.1021/acs.langmuir.2c01002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The anisotropic adhesion behavior of the gecko is closely related to their feet and is comprised of keratinous hairs, setae, where van der Waals forces permit attachment and detachment during locomotion. Previous research either achieved only isotropic adhesion behaviors or involved the complicated photolithography method. Here, we reported a simple way to achieve the anisotropic adhesion behaviors of gecko-inspired adhesives, consisting of micropillars with asymmetrically tilted orientation via the 3D printing technique. The adhesive forces of structured polymer pillars achieved 4-fold stronger, compared to controls with the plain surface. The anisotropic adhesion behavior is presented on the patterned surface and is two times stronger along the gripping direction compared to the releasing direction on the adhesives, which is attributed to the asymmetric stress distributions at the edges, as well as the stresses resulting from the moment with the sheared top. The finite element analysis is applied to demonstrate the stress distributions and displacement variations. This work provides the insight into the design and fabrication of gecko-inspired adhesives with anisotropic adhesion behaviors in practical applications.
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Affiliation(s)
- Weiwei Shi
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu 215316, China
- Environmental Research Center, Duke Kunshan University, Kunshan, Jiangsu 215316, China
- Department of Molecular Biomedical Sciences and Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina 27606, United States
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, North Carolina 27514, United States
| | - Xiao Cheng
- Department of Molecular Biomedical Sciences and Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina 27606, United States
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, North Carolina 27514, United States
| | - Ke Cheng
- Department of Molecular Biomedical Sciences and Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina 27606, United States
- Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, North Carolina 27514, United States
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Palecek AM, Garner AM, Klittich MR, Stark AY, Scherger JD, Bernard C, Niewiarowski PH, Dhinojwala A. An investigation of gecko attachment on wet and rough substrates leads to the application of surface roughness power spectral density analysis. Sci Rep 2022; 12:11556. [PMID: 35798824 PMCID: PMC9262901 DOI: 10.1038/s41598-022-15698-2] [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: 11/15/2021] [Accepted: 06/28/2022] [Indexed: 11/18/2022] Open
Abstract
The roughness and wettability of surfaces exploited by free-ranging geckos can be highly variable and attachment to these substrates is context dependent (e.g., presence or absence of surface water). Although previous studies focus on the effect of these variables on attachment independently, geckos encounter a variety of conditions in their natural environment simultaneously. Here, we measured maximum shear load of geckos in air and when their toes were submerged underwater on substrates that varied in both surface roughness and wettability. Gecko attachment was greater in water than in air on smooth and rough hydrophobic substrates, and attachment to rough hydrophilic substrates did not differ when tested in air or water. Attachment varied considerably with surface roughness and characterization revealed that routine measurements of root mean square height can misrepresent the complexity of roughness, especially when measured with single instruments. We used surface roughness power spectra to characterize substrate surface roughness and examined the relationship between gecko attachment performance across the power spectra. This comparison suggests that roughness wavelengths less than 70 nm predominantly dictate gecko attachment. This study highlights the complexity of attachment in natural conditions and the need for comprehensive surface characterization when studying biological adhesive system performance.
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Affiliation(s)
- Amanda M Palecek
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA. .,Department of Biology, The University of Akron, Akron, OH, USA. .,Department of Biological Sciences, Clemson University, Clemson, SC, USA.
| | - Austin M Garner
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA.,Department of Biology, Villanova University, Villanova, PA, USA
| | - Mena R Klittich
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Department of Polymer Science, The University of Akron, Akron, OH, USA.,Avery Dennison, Oegstgeest, The Netherlands
| | - Alyssa Y Stark
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA.,Department of Biology, Villanova University, Villanova, PA, USA
| | - Jacob D Scherger
- Department of Polymer Science, The University of Akron, Akron, OH, USA
| | - Craig Bernard
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA
| | - Peter H Niewiarowski
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA
| | - Ali Dhinojwala
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Polymer Science, The University of Akron, Akron, OH, USA
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26
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Rasmussen MH, Holler KR, Baio JE, Jaye C, Fischer DA, Gorb SN, Weidner T. Evidence that gecko setae are coated with an ordered nanometre-thin lipid film. Biol Lett 2022; 18:20220093. [PMID: 35857888 PMCID: PMC9256082 DOI: 10.1098/rsbl.2022.0093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 06/09/2022] [Indexed: 11/12/2022] Open
Abstract
The fascinating adhesion of gecko to virtually any material has been related to surface interactions of myriads of spatula at the tips of gecko feet. Surprisingly, the molecular details of the surface chemistry of gecko adhesion are still largely unknown. Lipids have been identified within gecko adhesive pads. However, the location of the lipids, the extent to which spatula are coated with lipids, and how the lipids are structured are still open questions. Lipids can modulate adhesion properties and surface hydrophobicity and may play an important role in adhesion. We have therefore studied the molecular structure of lipids at spatula surfaces using near-edge X-ray absorption fine structure imaging. We provide evidence that a nanometre-thin layer of lipids is present at the spatula surfaces of the tokay gecko (Gekko gecko) and that the lipids form ordered, densely packed layers. Such dense, thin lipid layers can effectively protect the spatula proteins from dehydration by forming a barrier against water evaporation. Lipids can also render surfaces hydrophobic and thereby support the gecko adhesive system by enhancement of hydrophobic-hydrophobic interactions with surfaces.
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Affiliation(s)
| | | | - Joe E. Baio
- The School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, USA
| | - Cherno Jaye
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Daniel A. Fischer
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Stanislav N. Gorb
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Kiel, Germany
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
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Song Y, Weng Z, Yuan J, Zhang L, Wang Z, Dai Z, Full RJ. Incline-dependent adjustments of toes in geckos inspire functional strategies for biomimetic manipulators. BIOINSPIRATION & BIOMIMETICS 2022; 17:046010. [PMID: 35390775 DOI: 10.1088/1748-3190/ac6557] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Geckos show versatility by rapidly maneuvering on diverse complex terrain because they benefit from their distributed, setae-covered toes and thus have the ability to generate reliable and adaptive attachment. Significant attention has been paid to their adhesive microstructures (setae), but the effectiveness of the gecko's adaptive attachment at the level of toes and feet remains unclear. In order to better understand the geckos' attachment, we first focused on the deployment of toes while challenging geckos to locomote on varying inclines. When the slope angle was less than 30°, their feet mainly interacted with the substrate using the bases of the toes and generated anisotropic frictional forces. As the slope angle increased to 90°, the participation of the toe bases was reduced. Instead, the setae contribution increased for the middle three toes of the front feet and for the first three toes of the hind feet. As the incline changed from vertical to inverted, the adhesive contribution of the toes of the front feet became more equal, whereas the effective adhesion contact of the hind feet gradually shifted to the toes oriented rearwards. Second, a mathematical model was established and then suggested the potential advantages of distributed control among the toes to regulate foot force. Finally, a physical foot model containing five compliant, adjustable toes was constructed and validated the discoveries with regard to the animals. Using the gecko toes' control strategies, the artificial foot demonstrated diverse behavior regulating attachment forces. The success of the foot prototype not only tested our understanding of the mechanism of biological attachment, but also provided a demonstration for the design and control of gecko-inspired attachment devices, grippers and other manipulators.
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Affiliation(s)
- Yi Song
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Zhiyuan Weng
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Jiwei Yuan
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Linghao Zhang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Zhouyi Wang
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Zhendong Dai
- College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, People's Republic of China
| | - Robert J Full
- Department of Integrative Biology, University of California, Berkeley, Valley Life Science Building, Berkeley, CA 94702, United States of America
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28
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Ding Q, Wu Z, Tao K, Wei Y, Wang W, Yang BR, Xie X, Wu J. Environment tolerant, adaptable and stretchable organohydrogels: preparation, optimization, and applications. MATERIALS HORIZONS 2022; 9:1356-1386. [PMID: 35156986 DOI: 10.1039/d1mh01871j] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Multiple stretchable materials have been successively developed and applied to wearable devices, soft robotics, and tissue engineering. Organohydrogels are currently being widely studied and formed by dispersing immiscible hydrophilic/hydrophobic polymer networks or only hydrophilic polymer networks in an organic/water solvent system. In particular, they can not only inherit and carry forward the merits of hydrogels, but also have some unique advantageous features, such as anti-freezing and water retention abilities, solvent resistance, adjustable surface wettability, and shape memory effect, which are conducive to the wide environmental adaptability and intelligent applications. This review first summarizes the structure, preparation strategy, and unique advantages of the reported organohydrogels. Furthermore, organohydrogels can be optimized for electro-mechanical properties or endowed with various functionalities by adding or modifying various functional components owing to their modifiability. Correspondingly, different optimization strategies, mechanisms, and advanced developments are described in detail, mainly involving the mechanical properties, conductivity, adhesion, self-healing properties, and antibacterial properties of organohydrogels. Moreover, the applications of organohydrogels in flexible sensors, energy storage devices, nanogenerators, and biomedicine have been summarized, confirming their unlimited potential in future development. Finally, the existing challenges and future prospects of organohydrogels are provided.
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Affiliation(s)
- Qiongling Ding
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Zixuan Wu
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Kai Tao
- The Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Yaoming Wei
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Weiyan Wang
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Bo-Ru Yang
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Xi Xie
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
| | - Jin Wu
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China.
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30
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Holler KR, Rasmussen MA, Baio JE, Jaye C, Fischer DA, Gorb SN, Weidner T. Structure of Keratins in Adhesive Gecko Setae Determined by Near-Edge X-ray Absorption Fine Structure Spectromicroscopy. J Phys Chem Lett 2022; 13:2193-2196. [PMID: 35230827 DOI: 10.1021/acs.jpclett.2c00004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Geckos have the astonishing ability to climb on vertical surfaces due to the adhesive properties of fibrous setae at the tips of their toe pads. While the adhesion mechanism principle, based on van der Waals interactions of myriads of spatula located at the outermost end of the setal arrays, has been studied extensively, there are still open questions about the chemistry of gecko setae. The gecko adhesive system is based on keratin fibrils assembled to support the entire setal structure. At the same time, the structure and alignment of keratin molecules within the ultrafine spatula tissue, which can support the enormous mechanical strain, still remain unknown. We have studied the molecular structure of gecko spatula using near-edge X-ray absorption fine structure (NEXAFS) imaging. We indeed found that the setae consist of a β-sheet structure aligned with the adhesion direction of the setae. Such alignment may provide mechanical stability to the setae and resistance to wear across different length scales.
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Affiliation(s)
| | | | - Joe E Baio
- The School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States
| | - Cherno Jaye
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Daniel A Fischer
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, 24118 Kiel, Germany
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
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31
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Chan ST, Varchanis S, Haward SJ, Shen AQ. Torsional instability of constant viscosity elastic liquid bridges. SOFT MATTER 2022; 18:1965-1977. [PMID: 35129559 DOI: 10.1039/d1sm01804c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
By experiment and simulation, we report that viscoelastic liquid bridges made of constant viscosity elastic liquids, a.k.a. Boger fluids, can be effectively destabilized by torsion. Under torsion, the deformation of the liquid bridge depends on the competition between elastocapillarity and torsion-induced normal stress effects. When the elastocapillary effect dominates, the liquid bridge undergoes elastocapillary instability and thins into a cylindrical thread, whose length increases and whose radius decays exponentially over time. When the torsion-induced normal stress effect dominates, the liquid bridge deforms in a way similar to edge fracture, a flow instability characterized by the sudden indentation of the fluid's free surface when a viscoelastic fluid is sheared at above a critical deformation rate. The vertical component of the normal stress causes the upper and lower portions of the liquid bridge to approach each other, and the radial component of the normal stress results in the liquid bridge thinning more quickly than under elastocapillarity. Whether such quick thinning continues until the bridge breaks depends on both the liquid bridge configuration and the level of torsion applied.
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Affiliation(s)
- San To Chan
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.
| | - Stylianos Varchanis
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.
| | - Simon J Haward
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.
| | - Amy Q Shen
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.
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32
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Grohmann C, Cohrs AL, Gorb SN. Underwater Attachment of the Water-Lily Leaf Beetle Galerucella nymphaeae (Coleoptera, Chrysomelidae). Biomimetics (Basel) 2022; 7:biomimetics7010026. [PMID: 35225918 PMCID: PMC8883964 DOI: 10.3390/biomimetics7010026] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/07/2022] [Accepted: 02/11/2022] [Indexed: 11/16/2022] Open
Abstract
While the reversible attachment of artificial structures underwater has moved into the focus of many recent publications, the ability of organisms to walk on and attach to surfaces underwater remains almost unstudied. Here, we describe the behaviour of the water-lily leaf beetle Galerucella nymphaeae when it adheres to surfaces underwater and compare its attachment properties on hydrophilic and hydrophobic surfaces underwater and in the air. The beetles remained attached to horizontal leaves underwater for a few minutes and then detached. When the leaf was inclined, the beetles started to move upward immediately. There was no difference in the size of the tarsal air bubble visible beneath the beetles’ tarsi underwater, between a hydrophilic (54° contact angle of water) and a hydrophobic (99°) surface. The beetles gained the highest traction forces on a hydrophilic surface in the air, the lowest on a hydrophobic surface in air, and intermediate traction on both surfaces underwater. The forces measured on both surfaces underwater did not differ significantly. We discuss factors responsible for the observed effects and conclude that capillary forces on the tarsal air bubble might play a major role in the adhesion to the studied surfaces.
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33
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Materzok T, Gorb S, Müller-Plathe F. Gecko adhesion: a molecular-simulation perspective on the effect of humidity. SOFT MATTER 2022; 18:1247-1263. [PMID: 35043818 DOI: 10.1039/d1sm01232k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gecko adhesion is investigated by molecular dynamics simulations. It is known, that the gecko adhesion system shows increased pull-off forces in humid environments. A coarse-grained model of gecko beta keratin, previously developed in our group, is extended and used to elucidate the molecular mechanisms involved in this humidity effect on adhesion. We show that neither the change of the elastic properties of gecko keratin, nor capillary forces, can solely explain the increased pull-off forces of wet gecko keratin. Instead, we establish a molecular picture of gecko adhesion where the interplay between capillary bridges and a mediator effect of water, enhances pull-off forces, consistent with observations in AFM experiments at high humidities. We find that water density is raised locally, in molecular scale asperities of the gecko keratin and that this increase in local water density smoothes the surface-spatula interface. Water, which is absorbed into the keratin, acts as a mediator, and leads during pull-off to the dominant contribution in the van der Waals energy, because the dispersion interactions between water and surface are primarily opposing the pull-off.
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Affiliation(s)
- Tobias Materzok
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287 Darmstadt, Germany.
| | - Stanislav Gorb
- Zoological Institute Functional Morphology and Biomechanics, Kiel University, Am Botanischen Garten 1-9, D-24118 Kiel, Germany.
| | - Florian Müller-Plathe
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Profile Area Thermofluids and Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, D-64287 Darmstadt, Germany.
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34
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Blelloch ND, Yarbrough HJ, Mirica KA. Stimuli-responsive temporary adhesives: enabling debonding on demand through strategic molecular design. Chem Sci 2021; 12:15183-15205. [PMID: 34976340 PMCID: PMC8635214 DOI: 10.1039/d1sc03426j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/07/2021] [Indexed: 11/24/2022] Open
Abstract
Stimuli-responsive temporary adhesives constitute a rapidly developing class of materials defined by the modulation of adhesion upon exposure to an external stimulus or stimuli. Engineering these materials to shift between two characteristic properties, strong adhesion and facile debonding, can be achieved through design strategies that target molecular functionalities. This perspective reviews the recent design and development of these materials, with a focus on the different stimuli that may initiate debonding. These stimuli include UV light, thermal energy, chemical triggers, and other potential triggers, such as mechanical force, sublimation, electromagnetism. The conclusion discusses the fundamental value of systematic investigations of the structure-property relationships within these materials and opportunities for unlocking novel functionalities in future versions of adhesives.
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Affiliation(s)
- Nicholas D Blelloch
- Burke Laboratory, Department of Chemistry, Dartmouth College Hanover New Hampshire 03755 USA http://www.miricagroup.com
| | - Hana J Yarbrough
- Burke Laboratory, Department of Chemistry, Dartmouth College Hanover New Hampshire 03755 USA http://www.miricagroup.com
| | - Katherine A Mirica
- Burke Laboratory, Department of Chemistry, Dartmouth College Hanover New Hampshire 03755 USA http://www.miricagroup.com
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Sudersan P, Kappl M, Pinchasik BE, Butt HJ, Endlein T. Wetting of the tarsal adhesive fluid determines underwater adhesion in ladybird beetles. J Exp Biol 2021; 224:jeb242852. [PMID: 34581416 PMCID: PMC8545753 DOI: 10.1242/jeb.242852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 09/21/2021] [Indexed: 11/23/2022]
Abstract
Many insects can climb smooth surfaces using hairy adhesive pads on their legs, mediated by tarsal fluid secretions. It was previously shown that a terrestrial beetle can even adhere and walk underwater. The naturally hydrophobic hairs trap an air bubble around the pads, allowing the hairs to make contact with the substrate as in air. However, it remained unclear to what extent such an air bubble is necessary for underwater adhesion. To investigate the role of the bubble, we measured the adhesive forces in individual legs of live but constrained ladybird beetles underwater in the presence and absence of a trapped bubble and compared these with its adhesion in air. Our experiments revealed that on a hydrophobic substrate, even without a bubble, the pads show adhesion comparable to that in air. On a hydrophilic substrate, underwater adhesion is significantly reduced, with or without a trapped bubble. We modelled the adhesion of a hairy pad using capillary forces. Coherent with our experiments, the model demonstrates that the wetting properties of the tarsal fluid alone can determine the ladybird beetles' adhesion to smooth surfaces in both air and underwater conditions and that an air bubble is not a prerequisite for their underwater adhesion. This study highlights how such a mediating fluid can serve as a potential strategy to achieve underwater adhesion via capillary forces, which could inspire artificial adhesives for underwater applications.
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Affiliation(s)
- Pranav Sudersan
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Michael Kappl
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Bat-El Pinchasik
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv-Yafo 69978, Israel
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Thomas Endlein
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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36
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England SJ, Robert D. The ecology of electricity and electroreception. Biol Rev Camb Philos Soc 2021; 97:383-413. [PMID: 34643022 DOI: 10.1111/brv.12804] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 11/29/2022]
Abstract
Electricity, the interaction between electrically charged objects, is widely known to be fundamental to the functioning of living systems. However, this appreciation has largely been restricted to the scale of atoms, molecules, and cells. By contrast, the role of electricity at the ecological scale has historically been largely neglected, characterised by punctuated islands of research infrequently connected to one another. Recently, however, an understanding of the ubiquity of electrical forces within the natural environment has begun to grow, along with a realisation of the multitude of ecological interactions that these forces may influence. Herein, we provide the first comprehensive collation and synthesis of research in this emerging field of electric ecology. This includes assessments of the role electricity plays in the natural ecology of predator-prey interactions, pollination, and animal dispersal, among many others, as well as the impact of anthropogenic activity on these systems. A detailed introduction to the ecology and physiology of electroreception - the biological detection of ecologically relevant electric fields - is also provided. Further to this, we suggest avenues for future research that show particular promise, most notably those investigating the recently discovered sense of aerial electroreception.
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Affiliation(s)
- Sam J England
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, U.K
| | - Daniel Robert
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, U.K
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37
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Song Q, Liu K, Sun W, Chen R, Ji J, Jiao Y, Gao T, Ye J. Lateral and Normal Capillary Force Evolution of a Reciprocating Liquid Bridge. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11737-11749. [PMID: 34597055 DOI: 10.1021/acs.langmuir.1c01635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Capillary forces of a shearing liquid bridge can significantly affect the friction and adhesion of interacting surfaces, but the underlying mechanisms remain unclear. We custom built a surface force apparatus (SFA, ±2 μN) equipped with in situ optical microscopy and performed normal and lateral force measurements on a reciprocating water bridge formed between two flat plates. A modified wedge method was developed to correct the unique force measurement errors caused by the changing bridge geometry and position. The results found (1) strong linear relations among the bridge shear displacement, the cosine difference between the left and right contact angles, and the lateral adhesion force and (2) the normal adhesion force increased monotonically up to 13% as the bridge geometry approached its axisymmetric state. Quasi-static force analyses based on a newly developed decahedral model showed good agreement with the experiments and improved accuracy compared with that of cylindrical or rectangular column models previously proposed in the literature. Although limited in certain aspects, this study may (1) prove helpful to the design and analysis of liquid bridge force experiments on platforms similar to the SFA used in this study and (2) help to bridge the gap between friction and liquid bridge physics in the literature.
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Affiliation(s)
- Qingrui Song
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Kun Liu
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Wei Sun
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Rongxin Chen
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Jiawei Ji
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Yunlong Jiao
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Tianyan Gao
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
| | - Jiaxin Ye
- Institute of Tribology School of Mechanical Engineering, Hefei University of Technology, Hefei, Anhui 230009, China
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Lee HJ, Baik S, Hwang GW, Song JH, Kim DW, Park BY, Min H, Kim JK, Koh JS, Yang TH, Pang C. An Electronically Perceptive Bioinspired Soft Wet-Adhesion Actuator with Carbon Nanotube-Based Strain Sensors. ACS NANO 2021; 15:14137-14148. [PMID: 34425674 DOI: 10.1021/acsnano.1c05130] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The development of bioinspired switchable adhesive systems has promising solutions in various industrial/medical applications. Switchable and perceptive adhesion regardless of the shape or surface shape of the object is still challenging in dry and aquatic surroundings. We developed an electronic sensory soft adhesive device that recapitulates the attaching, mechanosensory, and decision-making capabilities of a soft adhesion actuator. The soft adhesion actuator of an artificial octopus sucker may precisely control its robust attachment against surfaces with various topologies in wet environments as well as a rapid detachment upon deflation. Carbon nanotube-based strain sensors are three-dimensionally coated onto the irregular surface of the artificial octopus sucker to mimic nerve-like functions of an octopus and identify objects via patterns of strain distribution. An integration with machine learning complements decision-making capabilities to predict the weight and center of gravity for samples with diverse shapes, sizes, and mechanical properties, and this function may be useful in turbid water or fragile environments, where it is difficult to utilize vision.
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Affiliation(s)
- Heon Joon Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Sangyul Baik
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Gui Won Hwang
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Jin Ho Song
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
- Department SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Da Wan Kim
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Bo-Yong Park
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal H3A 2B4, Quebec, Canada
- Department of Data Science, Inha University, Incheon 22212, Republic of Korea
| | - Hyeongho Min
- Department SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Jung Kyu Kim
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
| | - Je-Sung Koh
- Department of Mechanical Engineering, Ajou University, Suwon 16499, Gyeonggi-do, Republic of Korea
| | - Tae-Heon Yang
- Department of Electronic Engineering, Korea National University of Transportation, Chungju-si 27469, Chungbuk, Republic of Korea
| | - Changhyun Pang
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 16419, Gyeonggi-do, Republic of Korea
- Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Suwon 16419, Gyunggi-do, Republic of Korea
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Büscher TH, Gorb SN. Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2021; 12:725-743. [PMID: 34354900 PMCID: PMC8290099 DOI: 10.3762/bjnano.12.57] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/30/2021] [Indexed: 05/25/2023]
Abstract
Adhesive pads are functional systems with specific micro- and nanostructures which evolved as a response to specific environmental conditions and therefore exhibit convergent traits. The functional constraints that shape systems for the attachment to a surface are general requirements. Different strategies to solve similar problems often follow similar physical principles, hence, the morphology of attachment devices is affected by physical constraints. This resulted in two main types of attachment devices in animals: hairy and smooth. They differ in morphology and ultrastructure but achieve mechanical adaptation to substrates with different roughness and maximise the actual contact area with them. Species-specific environmental surface conditions resulted in different solutions for the specific ecological surroundings of different animals. As the conditions are similar in discrete environments unrelated to the group of animals, the micro- and nanostructural adaptations of the attachment systems of different animal groups reveal similar mechanisms. Consequently, similar attachment organs evolved in a convergent manner and different attachment solutions can occur within closely related lineages. In this review, we present a summary of the literature on structural and functional principles of attachment pads with a special focus on insects, describe micro- and nanostructures, surface patterns, origin of different pads and their evolution, discuss the material properties (elasticity, viscoelasticity, adhesion, friction) and basic physical forces contributing to adhesion, show the influence of different factors, such as substrate roughness and pad stiffness, on contact forces, and review the chemical composition of pad fluids, which is an important component of an adhesive function. Attachment systems are omnipresent in animals. We show parallel evolution of attachment structures on micro- and nanoscales at different phylogenetic levels, focus on insects as the largest animal group on earth, and subsequently zoom into the attachment pads of the stick and leaf insects (Phasmatodea) to explore convergent evolution of attachment pads at even smaller scales. Since convergent events might be potentially interesting for engineers as a kind of optimal solution by nature, the biomimetic implications of the discussed results are briefly presented.
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Affiliation(s)
- Thies H Büscher
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany
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Li W, Liu J, Wei W, Qian K. Harnessing reversible dry adhesion using shape memory polymer microparticles. RSC Adv 2021; 11:19616-19622. [PMID: 35479233 PMCID: PMC9033592 DOI: 10.1039/d1ra01473k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/17/2021] [Indexed: 11/21/2022] Open
Abstract
Reversible adhesion switching on the micron scale greatly extends the functionality of shape memory polymers. Herein, we report the first usage of polystyrene microparticles for the reversible dry adhesive of the on/off switch between bonding and debonding. The reversible dry adhesive property is attributed to the stiffness change under the varying temperature of the polystyrene microparticle, as well as its ability to lock a temporary shape and recover to its original shape. The decrease in the modulus/viscosity of polystyrene microparticles at high temperature improves the surface wetting/contact and enhances the adhesive bond by contact pressure. Then, when heating above its glass transition temperature after bonding, the adhesive recovers to its initial shape, resulting in almost a zero adhesion strength. Besides, adhesion tests reveal that the magnitude of adhesion variations depends on substrates, contact pressures, and particle sizes. Therefore, as a thermotropic-induced shape memory material, the adhesive (polystyrene microparticles) can be used to create joints and can be heated to achieve its own restoration. Shape memory polymers can provide excellent bonding property because of their shape memory effects. This paper proposes an adhesive unit that is capable of repeatable smart adhesion and exhibits reversible adhesion under heating.![]()
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Affiliation(s)
- Wenbing Li
- Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University Wuxi 214122 PR China
| | - Junhao Liu
- Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University Wuxi 214122 PR China
| | - Wanting Wei
- Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University Wuxi 214122 PR China
| | - Kun Qian
- Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University Wuxi 214122 PR China
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Singla S, Jain D, Zoltowski CM, Voleti S, Stark AY, Niewiarowski PH, Dhinojwala A. Direct evidence of acid-base interactions in gecko adhesion. SCIENCE ADVANCES 2021; 7:7/21/eabd9410. [PMID: 34138740 PMCID: PMC8133704 DOI: 10.1126/sciadv.abd9410] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 03/29/2021] [Indexed: 05/06/2023]
Abstract
While it is generally accepted that van der Waals (vdW) forces govern gecko adhesion, several studies indicate contributions from non-vdW forces and highlight the importance of understanding the adhesive contact interface. Previous work hypothesized that the surface of gecko setae is hydrophobic, with nonpolar lipid tails exposed on the surface. However, direct experimental evidence supporting this hypothesis and its implications on the adhesion mechanism is lacking. Here, we investigate the sapphire-setae contact interface using interface-sensitive spectroscopy and provide direct evidence of the involvement of acid-base interactions between polar lipid headgroups exposed on the setal surface and sapphire. During detachment, a layer of unbound lipids is left as a footprint due to cohesive failure within the lipid layer, which, in turn, reduces wear to setae during high stress sliding. The absence of this lipid layer enhances adhesion, despite a small setal-substrate contact area. Our results show that gecko adhesion is not exclusively a vdW-based, residue-free system.
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Affiliation(s)
- Saranshu Singla
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Dharamdeep Jain
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Chelsea M Zoltowski
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Sriharsha Voleti
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA
| | - Alyssa Y Stark
- Integrated Bioscience Program, University of Akron, Akron, OH 44325-3908, USA
- Department of Biology, Villanova University, Villanova, PA 19085, USA
| | | | - Ali Dhinojwala
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH 44325-3909, USA.
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43
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Ringenwald BE, Bogacki EC, Narvaez CA, Stark AY. The effect of variable temperature, humidity, and substrate wettability on Gecko (Gekko gecko) locomotor performance and behavior. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 335:454-463. [PMID: 33830673 DOI: 10.1002/jez.2463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 11/07/2022]
Abstract
Adhesive and locomotor performances of geckos are inherently linked by specialized morphological and biomechanical features. As such, we predict that conditions that lead to poor adhesive performance (i.e., low resistance to applied force while clinging) also lead to poor locomotor performance and behavior (i.e., slowed running speed, increased frequency and duration of stops, more failed or incomplete runs). In this study, we test the prediction that running speed changes as a function of adhesive performance in variable temperature (12 and 32°C), humidity (30, 55, 70, 80% relative humidity), and substrate wettability (hydrophilic glass, intermediately wetting plexiglass). We also expect other locomotor performance traits and behaviors, such as stopping and avoiding treatment conditions, to change as a function of adhesive performance. The results of this study do not fully support our prediction: gecko locomotor performance does not change as a function of humidity or substrate wettability, unlike adhesive performance. As an anticipated result of ectothermy, geckos run significantly slower and stop more frequently and longer at 12°C than 32°C. At high temperature, geckos required significantly more running attempts on hydrophilic glass than plexiglass to complete the experimental procedure, suggesting that this treatment condition is unfavorable. The results of this study highlight the robust locomotive response of geckos to variation in adhesive performance and environmental conditions, and have significant implications for predictions about habitat use and behavior in their natural environment.
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Affiliation(s)
| | - Erin C Bogacki
- Department of Biology, Villanova University, Villanova, Pennsylvania, USA
| | - Carla A Narvaez
- Department of Biology, Villanova University, Villanova, Pennsylvania, USA
| | - Alyssa Y Stark
- Department of Biology, Villanova University, Villanova, Pennsylvania, USA
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44
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Bovone G, Dudaryeva OY, Marco-Dufort B, Tibbitt MW. Engineering Hydrogel Adhesion for Biomedical Applications via Chemical Design of the Junction. ACS Biomater Sci Eng 2021; 7:4048-4076. [PMID: 33792286 DOI: 10.1021/acsbiomaterials.0c01677] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hydrogel adhesion inherently relies on engineering the contact surface at soft and hydrated interfaces. Upon contact, adhesion normally occurs through the formation of chemical or physical interactions between the disparate surfaces. The ability to form these adhesion junctions is challenging for hydrogels as the interfaces are wet and deformable and often contain low densities of functional groups. In this Review, we link the design of the binding chemistries or adhesion junctions, whether covalent, dynamic covalent, supramolecular, or physical, to the emergent adhesive properties of soft and hydrated interfaces. Wet adhesion is useful for bonding to or between tissues and implants for a range of biomedical applications. We highlight several recent and emerging adhesive hydrogels for use in biomedicine in the context of efficient junction design. The main focus is on engineering hydrogel adhesion through molecular design of the junctions to tailor the adhesion strength, reversibility, stability, and response to environmental stimuli.
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Affiliation(s)
- Giovanni Bovone
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Oksana Y Dudaryeva
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Bruno Marco-Dufort
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Mark W Tibbitt
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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45
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Chowdhry G, Chang YM, Frampton JP, Kreplak L. Polymer entanglement drives formation of fibers from stable liquid bridges of highly viscous dextran solutions. SOFT MATTER 2021; 17:1873-1880. [PMID: 33409512 DOI: 10.1039/d0sm01550d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Liquid bridges have been studied for over 200 years due to their occurrence in many natural and industrial phenomena. Most studies focus on millimeter scale liquid bridges of Newtonian liquids. Here, reptation theory was used to explain the formation of 10 cm long liquid bridges of entangled polymer solutions, which subsequently stabilize into polymer fibers with tunable diameters between 3 and 20 mm. To control the fiber formation process, a horizontal single-fiber contact drawing system was constructed consisting of a motorized stage, a micro-needle, and a liquid filled reservoir. Analyzing the liquid bridge rupture statistics as a function of elongation speed, solution concentration and dextran molecular weight revealed that the fiber formation process was governed by a single timescale attributed to the relaxation of entanglements within the polymer solution. Further characterization revealed that more viscous solutions produced fibers of larger diameters due to secondary flow dynamics. Verification that protein additives such as type I collagen had minimal effect on fiber formation demonstrates the potential application in biomaterial fabrication.
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Affiliation(s)
- Gurkaran Chowdhry
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
| | - Yi Ming Chang
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
| | - John P Frampton
- School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada. and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
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46
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Garner AM, Russell AP. Revisiting the classification of squamate adhesive setae: historical, morphological and functional perspectives. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202039. [PMID: 33972877 PMCID: PMC8074656 DOI: 10.1098/rsos.202039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Research on gecko-based adhesion has become a truly interdisciplinary endeavour, encompassing many disciplines within the natural and physical sciences. Gecko adhesion occurs by the induction of van der Waals intermolecular (and possibly other) forces between substrata and integumentary filaments (setae) terminating in at least one spatulate tip. Gecko setae have increasingly been idealized as structures with uniform dimensions and a particular branching pattern. Approaches to developing synthetic simulacra have largely adopted such an idealized form as a foundational template. Observations of entire setal fields of geckos and anoles have, however, revealed extensive, predictable variation in setal form. Some filaments of these fields do not fulfil the morphological criteria that characterize setae and, problematically, recent authors have applied the term 'seta' to structurally simpler and likely non-adhesively competent fibrils. Herein we briefly review the history of the definition of squamate setae and propose a standardized classificatory scheme for epidermal outgrowths based on a combination of whole animal performance and morphology. Our review is by no means comprehensive of the literature regarding the form, function, and development of the adhesive setae of squamates and we do not address significant advances that have been made in many areas (e.g. cell biology of setae) that are largely tangential to their classification and identification. We contend that those who aspire to simulate the form and function of squamate setae will benefit from a fuller appreciation of the diversity of these structures, thereby assisting in the identification of features most relevant to their objectives.
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Affiliation(s)
- Austin M. Garner
- Integrated Bioscience Program, Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
| | - Anthony P. Russell
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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47
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Baik S, Hwang GW, Jang S, Jeong S, Kim KH, Yang TH, Pang C. Bioinspired Microsphere-Embedded Adhesive Architectures for an Electrothermally Actuating Transport Device of Dry/Wet Pliable Surfaces. ACS APPLIED MATERIALS & INTERFACES 2021; 13:6930-6940. [PMID: 33523645 DOI: 10.1021/acsami.0c21847] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
For highly conformable and universal transport devices, bioinspired dry adhesion systems with reversible molecular attractions (e.g., van der Waals forces, capillarity, or suction stress) between the engaged surfaces have recently become favorable for various dry/wet processes in flexible devices and medical applications. In addition, many efforts have been made for switchable attachments of such adhesives by employing costly sophisticated systems such as mechanically deformable chucks, UV-radiating components, or fluidic channels. In this work, we propose a simple electrothermally actuating transport device based on an octopus-inspired microsphere-embedded sucker (OMS). The adhesive with microsphere-embedded suckers offers enhanced adhesion on dry/wet surfaces, in accordance with investigation of the geometric and materials parameters of the novel suction architecture for maximizing adhesion interactions. Inspired by muscle actuation of octopus tentacles, we laminate the electrothermally reactive poly(3,4-ethylenedioxy thiophene):poly(styrenesulfonic acid) (PEDOT:PSS) layer on the backside of the OMS adhesive patch. By controlling inputs of electrical energy, our assembled actuator may actively expand and contract reversibly to induce switchable attachments and detachments. Our bioinspired device can be integrated onto a robotic arm to attach and release against dry/wet flexible thin objects.
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Affiliation(s)
- Sangyul Baik
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Gui Won Hwang
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Siyeon Jang
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Suyeon Jeong
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Ki Hyun Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Tae-Heon Yang
- Department of Electronic Engineering, Korea National University of Transportation, Chungju 27469, Republic of Korea
| | - Changhyun Pang
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, Gyeonggi-do 16419, Republic of Korea
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48
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Kizilkan E, Strueben J, Staubitz A, Gorb SN. Bioinspired photocontrollable microstructured transport device. Sci Robot 2021; 2:2/2/eaak9454. [PMID: 33157866 DOI: 10.1126/scirobotics.aak9454] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 12/15/2016] [Indexed: 11/02/2022]
Abstract
Geckos, which can walk upside down on vertical and underneath horizontal surfaces, owe this ability to the hierarchical structures under their toes. These structures are responsible for substantial adhesion and, at the same time, for quick detachment by mechanical stimulus through leg movements. Inspired by such stimuli-responsive systems in nature, we developed an artificial, photocontrollable microstructured transport device. Through tunable ultraviolet light illumination, the adhesive ability of this bioinspired transport device is reduced up to a factor of 2.7 in terms of adhesive forces and is quickly recovered when the light stimulus ceases. This bioinspired photocontrollable device has been used in a pick-up and drop-down system for transporting planar and three-dimensional solid objects.
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Affiliation(s)
- Emre Kizilkan
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
| | - Jan Strueben
- Otto Diels Institute for Organic Chemistry, Kiel University, Otto-Hahn-Platz 4, 24118 Kiel, Germany.,Institute for Organic and Analytical Chemistry, University of Bremen, Leobener Straße NW 2 C, 28359 Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, Bibliothekstraße 1, 28359 Bremen, Germany
| | - Anne Staubitz
- Otto Diels Institute for Organic Chemistry, Kiel University, Otto-Hahn-Platz 4, 24118 Kiel, Germany. .,Institute for Organic and Analytical Chemistry, University of Bremen, Leobener Straße NW 2 C, 28359 Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, Bibliothekstraße 1, 28359 Bremen, Germany
| | - Stanislav N Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
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49
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Garner AM, Wilson MC, Wright C, Russell AP, Niewiarowski PH, Dhinojwala A. The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness. J Anat 2020; 238:1143-1155. [PMID: 33319377 PMCID: PMC8053591 DOI: 10.1111/joa.13377] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/11/2020] [Accepted: 11/16/2020] [Indexed: 01/24/2023] Open
Abstract
The functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated to be important in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here, we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings set the stage for future comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.
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Affiliation(s)
- Austin M Garner
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA
| | - Michael C Wilson
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Department of Polymer Science, The University of Akron, Akron, OH, USA
| | - Caitlin Wright
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA
| | - Anthony P Russell
- Department of Biological Sciences, The University of Calgary, Calgary, AB, Canada
| | - Peter H Niewiarowski
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Biology, The University of Akron, Akron, OH, USA
| | - Ali Dhinojwala
- Gecko Adhesion Research Group, The University of Akron, Akron, OH, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH, USA.,Department of Polymer Science, The University of Akron, Akron, OH, USA
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Mitchell CT, Dayan CB, Drotlef DM, Sitti M, Stark AY. The effect of substrate wettability and modulus on gecko and gecko-inspired synthetic adhesion in variable temperature and humidity. Sci Rep 2020; 10:19748. [PMID: 33184356 PMCID: PMC7665207 DOI: 10.1038/s41598-020-76484-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/28/2020] [Indexed: 01/23/2023] Open
Abstract
Gecko adhesive performance increases as relative humidity increases. Two primary mechanisms can explain this result: capillary adhesion and increased contact area via material softening. Both hypotheses consider variable relative humidity, but neither fully explains the interactive effects of temperature and relative humidity on live gecko adhesion. In this study, we used live tokay geckos (Gekko gecko) and a gecko-inspired synthetic adhesive to investigate the roles of capillary adhesion and material softening on gecko adhesive performance. The results of our study suggest that both capillary adhesion and material softening contribute to overall gecko adhesion, but the relative contribution of each depends on the environmental context. Specifically, capillary adhesion dominates on hydrophilic substrates, and material softening dominates on hydrophobic substrates. At low temperature (12 °C), both capillary adhesion and material softening likely produce high adhesion across a range of relative humidity values. At high temperature (32 °C), material softening plays a dominant role in adhesive performance at an intermediate relative humidity (i.e., 70% RH).
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Affiliation(s)
- Christopher T Mitchell
- Department of Biology, Villanova University, 800 E. Lancaster Ave., Villanova, PA, 19085, USA
| | - Cem Balda Dayan
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Dirk-M Drotlef
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - Alyssa Y Stark
- Department of Biology, Villanova University, 800 E. Lancaster Ave., Villanova, PA, 19085, USA.
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