Special Issue "Micro- and Nano-Structured Bio-Inspired Surfaces"

A special issue of Biomimetics (ISSN 2313-7673).

Deadline for manuscript submissions: closed (31 January 2017).

Special Issue Editor

Prof. Dr. Giuseppe Carbone
Website
Guest Editor
Dipartimento di Meccanica-Matematica-Management DMMM, Campus, Via Orabona 4, 70125 Bari, Italy
Interests: contact mechanics; tribology; wetting and interfaces; applied computational mathematics; automotive systems engineerin; rheology of materials
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Special Issue Information

Dear Colleagues,

Interaction on contact between two surfaces, either in dry or wet conditions, plays a major role in a large number of physical phenomena and engineering devices. Examples are reversible adhesives, protective coatings, low friction, and self-cleaning surfaces. In all these cases, the geometry, chemistry, and physics of the surface morphology play a fundamental role in determining the real behaviour of the interface. Notwithstanding the real complexity of contact phenomena, nature has learned how to tune surface morphology, chemistry, and physics to find optimal solutions. We have all been amazed at how certain lizards and many insects (ants, bees, cockroaches and grasshoppers) are able to walk on walls and ceilings. This ability is even more wondrous when we note that these surfaces can be as rough as a cinderblock wall or a smooth glass window. However, there are many other examples: the ultra-phobic surfaces of water striders (Gerris remigis) foot pads, the self-cleaning properties of Lotus leaves, or, rather, the super-low friction properties of shark skin.

However, just mimicking nature is not as simple as it seems, and understanding the key mechanisms behind the superb tribological properties of micro- and nano-structured surfaces is the real breakthrough for the successful engineering design of artificial surfaces with superlative tribological properties.

These emergent novel applications have drawn the attention of a larger and interdisciplinary scientific community, involving expertise from fields such as engineering, physics, chemistry, biology, and mathematics. The purpose of this special issue is to provide a forum and a survey for the most recent advances in the field of micro- nano-structured surfaces addressing the challenges in modern engineering applications.

We invite authors to submit original research and review articles, which stimulate the continuing efforts to understand and improve the knowledge in this field.

Dr. Giuseppe Carbone
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Biomimetics is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microstructures
  • nanostructures
  • biomimetics
  • adhesion
  • wetting
  • friction
  • tribology
  • roughness

Published Papers (7 papers)

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Research

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Open AccessArticle
Fabrication of Mechanically Stable Superhydrophobic Aluminium Surface with Excellent Self-Cleaning and Anti-Fogging Properties
Biomimetics 2017, 2(1), 2; https://doi.org/10.3390/biomimetics2010002 - 23 Feb 2017
Cited by 19
Abstract
The development of a self-cleaning and anti-fogging superhydrophobic coating for aluminium surfaces that is durable in aggressive conditions has raised tremendous interest in materials science. In this work, a superhydrophobic Al surface was synthesized by employing chemical etching technique with a mixture of [...] Read more.
The development of a self-cleaning and anti-fogging superhydrophobic coating for aluminium surfaces that is durable in aggressive conditions has raised tremendous interest in materials science. In this work, a superhydrophobic Al surface was synthesized by employing chemical etching technique with a mixture of hydrochloric and nitric acids, followed by passivation with lauric acid. The surface morphology analysis revealed the presence of rough microstructures on the coated Al surface. Superhydrophobicity with water contact angle of 170 ± 3.9° and sliding angle of 4 ± 0.5° was achieved. The surface bounced off the high-speed water jet, indicating the excellent water-repellent nature of the coating. It also continuously floated on a water surface for four weeks, showing its excellent buoyancy. Additionally, the coating maintained its superhydrophobicity after undergoing 100 cycles of adhesive tape peeling test. Its superhydrophobic nature withstood 90° and 180° bending and repeated folding and de-folding. The coating exhibits an excellent self-cleaning property. In a low temperature condensation test, almost no accumulation of water drops on the surface showed the excellent anti-fogging property of the coating. This approach can be applied to any size and shape of Al surface, and hence has great industrial applications. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Open AccessArticle
Plasma-Textured Teflon: Repulsion in Air of Water Droplets and Drag Reduction Underwater
Biomimetics 2017, 2(1), 1; https://doi.org/10.3390/biomimetics2010001 - 23 Jan 2017
Cited by 4
Abstract
A superhydrophobic behavior can be obtained by properly modifying the surface topography of Teflon or other fluorinated polymers having an inherent hydrophobic character. According to this strategy, we have micro/nanotextured Teflon both as plane material (sheets) and as three-dimensional (3D) object (spheres) with [...] Read more.
A superhydrophobic behavior can be obtained by properly modifying the surface topography of Teflon or other fluorinated polymers having an inherent hydrophobic character. According to this strategy, we have micro/nanotextured Teflon both as plane material (sheets) and as three-dimensional (3D) object (spheres) with a single step plasma process. The obtained textured Teflon samples were compared with those made of pristine Teflon in air, in terms of repulsion of impacting water droplets, and underwater, in terms of air layer behavior under static and dynamic conditions. The latter case was investigated by subjecting the spheres to a vertical fall in water. Modified surfaces present nanofilaments on the top of micrometric vertical structures, which can increase the air retaining capacity, resulting in a biomimicry effect due to a similarity with the Salvinia molesta leaf. On this surface, repulsion of impacting water droplets can be as fast as previously reached only on heated solids. Also, the air layer over the modified spheres underwater is shown to play a role in the observed reduction of hydrodynamic drag onto the moving object. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Open AccessArticle
A Green’s Function Molecular Dynamics Approach to the Mechanical Contact between Thin Elastic Sheets and Randomly Rough Surfaces
Biomimetics 2016, 1(1), 7; https://doi.org/10.3390/biomimetics1010007 - 27 Oct 2016
Cited by 2
Abstract
Adhesion of biological systems is often made possible through thin elastic layers, such as human skin. To address the question of when a layer is sufficiently thin to become adhesive, we extended Green’s function molecular dynamics (GFMD) to account for the finite thickness [...] Read more.
Adhesion of biological systems is often made possible through thin elastic layers, such as human skin. To address the question of when a layer is sufficiently thin to become adhesive, we extended Green’s function molecular dynamics (GFMD) to account for the finite thickness of an elastic body that is supported by a fluid foundation. We observed that thin layers can much better accommodate rough counterfaces than thick structures. As a result, the contact area is enlarged, in particular, when the width of the layer w approaches or even falls below the short-wavelength cutoff λ s of the surface spectra. In the latter case, the proportionality coefficient between area and load scales is ( w / λ s ) 3 , which is consistent with Persson’s contact mechanics theory. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Open AccessArticle
A Theoretical Characterization of Curvature Controlled Adhesive Properties of Bio-Inspired Membranes
Biomimetics 2016, 1(1), 3; https://doi.org/10.3390/biomimetics1010003 - 19 Apr 2016
Cited by 3
Abstract
Some biological systems, such as the tree frog, Litoria caerulea, and the bush-cricket, Tettigonia viridissima, have developed the ability to control adhesion by changing the curvature of their pads. Active control systems of adhesion inspired by these biological models can be [...] Read more.
Some biological systems, such as the tree frog, Litoria caerulea, and the bush-cricket, Tettigonia viridissima, have developed the ability to control adhesion by changing the curvature of their pads. Active control systems of adhesion inspired by these biological models can be very attractive for the development of devices with controllable adhesive properties. In this paper, we present a theory describing the adhesive behavior of an artificial system consisting of an inflatable membrane clamped to a metallic cylinder and filled with air. In such a system, by controlling the internal pressure acting on the membrane, it is possible to modulate the adhesive strength. In particular, an increase of the internal pressure and, hence, the curvature of the membrane, results in a decrease of the pull-off force. Results predicted by the theoretical model are in good agreement with experimental data. The model explains the apparent contradictory results observed for the thick membrane with zero curvature. In fact, in this case, large pull-off forces should be expected, but zero values are measured due to an initial small misalignment between indenter and membrane, which is not possible to control with precision during the experiments. The present model might help to achieve a better understanding of the adhesion behavior of biological systems and of the fingertips that, in a broad sense, may be regarded as shell-like structures. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Open AccessArticle
Switchable Adhesion Surfaces with Enhanced Performance Against Rough Counterfaces
Biomimetics 2016, 1(1), 2; https://doi.org/10.3390/biomimetics1010002 - 25 Feb 2016
Cited by 4
Abstract
In a recent study, we demonstrated that the pressurization of micro-fluidic features introduced in the subsurface of a soft polymer can be used to actively modify the magnitude of the adhesion to a harder counterface by changing its waviness or long wavelength undulations. [...] Read more.
In a recent study, we demonstrated that the pressurization of micro-fluidic features introduced in the subsurface of a soft polymer can be used to actively modify the magnitude of the adhesion to a harder counterface by changing its waviness or long wavelength undulations. In that case, both contacting surfaces had very smooth finishes with root-mean-square roughnesses of less than 20 nm. These values are far from those of many engineering surfaces, which usually have a naturally occurring roughness of between ten and a hundred times this value. In this work, we demonstrate that appropriate surface features, specifically relatively slender “fibrils”, can enhance the ability of a such a soft surface to adhere to a hard, but macroscopically rough, counterface, while still maintaining the possibility of switching the adhesion force from one level to another. Conversely, stiffer more conical surface features can suppress adhesion even against a smooth counterface. Examples of each form of topography can be found in the natural world. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Review

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Open AccessReview
Effective Elastic Modulus of Structured Adhesives: From Biology to Biomimetics
Biomimetics 2017, 2(3), 10; https://doi.org/10.3390/biomimetics2030010 - 29 Jun 2017
Cited by 20
Abstract
Micro- and nano-hierarchical structures (lamellae, setae, branches, and spatulae) on the toe pads of many animals play key roles for generating strong but reversible adhesion for locomotion. The hierarchical structure possesses significantly reduced, effective elastic modulus (Eeff), as compared to [...] Read more.
Micro- and nano-hierarchical structures (lamellae, setae, branches, and spatulae) on the toe pads of many animals play key roles for generating strong but reversible adhesion for locomotion. The hierarchical structure possesses significantly reduced, effective elastic modulus (Eeff), as compared to the inherent elastic modulus (Einh) of the corresponding biological material (and therefore contributes to a better compliance with the counterpart surface). Learning from nature, three types of hierarchical structures (namely self-similar pillar structure, lamella–pillar hybrid structure, and porous structure) have been developed and investigated. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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Open AccessReview
Vibrations and Spatial Patterns Change Effective Wetting Properties of Superhydrophobic and Regular Membranes
Biomimetics 2016, 1(1), 4; https://doi.org/10.3390/biomimetics1010004 - 04 Aug 2016
Cited by 2
Abstract
Small-amplitude fast vibrations and small surface micropatterns affect properties of various systems involving wetting, such as superhydrophobic surfaces and membranes. We review a mathematical method of averaging the effect of small spatial and temporal patterns. For small fast vibrations, this method is known [...] Read more.
Small-amplitude fast vibrations and small surface micropatterns affect properties of various systems involving wetting, such as superhydrophobic surfaces and membranes. We review a mathematical method of averaging the effect of small spatial and temporal patterns. For small fast vibrations, this method is known as the method of separation of motions. The vibrations are substituted by effective force or energy terms, leading to vibration-induced phase control. A similar averaging method can be applied to surface micropatterns leading surface texture-induced phase control. We argue that the method provides a framework that allows studying such effects typical to biomimetic surfaces, such as superhydrophobicity, membrane penetration and others. Patterns and vibration can effectively jam holes and pores in vessels with liquid, separate multi-phase flow, change membrane properties, result in propulsion, and lead to many other multiscale, non-linear effects. Here, we discuss the potential application of these effects to novel superhydrophobic membranes. Full article
(This article belongs to the Special Issue Micro- and Nano-Structured Bio-Inspired Surfaces)
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