Characterisation of a micrometer-scale active plasmonic element by means of complementary computational and experimental methods

• Ciarán Barron,
• Giulia Di Fazio,
• Samuel Kenny,
• Silas O’Toole,
• Robin O’Reilly and
• Dominic Zerulla

Beilstein J. Nanotechnol. 2023, 14, 110–122, doi:10.3762/bjnano.14.12

• simulate an incoming TM wave, and Floquet periodic conditions were imposed on the side boundaries. A perfectly matched layer (PML) was added on top of the air layer in order to avoid back reflection. Total reflectivity data were collected at the output port. Integrating this simulation setup with the

Dry under water: air retaining properties of large-scale elastomer foils covered with mushroom-shaped surface microstructures

• Matthias Mail,
• Stefan Walheim,
• Thomas Schimmel,
• Wilhelm Barthlott,
• Stanislav N. Gorb and
• Lars Heepe

Beilstein J. Nanotechnol. 2022, 13, 1370–1379, doi:10.3762/bjnano.13.113

• Effect, the capability to keep a stable air layer when submerged under water. Such air layers are of great importance, e.g., for drag reduction (passive air lubrication), antifouling, sensor applications or oil–water separation. Some biological models, e.g., the floating fern Salvinia or the backswimmer

• air layer under water for more than two weeks. Further, the stability of the air layer under pressure was investigated and these results are compared with the predicted theoretical values for air retention of microstructured surfaces. Here, we could show that they fit to the theoretical predictions

• and that the biomimetic elastomer foil is a promising base for the development of an economically and efficient biomimetic air retaining surface for a broad range of technical applications. Keywords: adhesive tape; air layer; air retention; bionics; fouling; gecko tape; mushroom structures; passive

Straight roads into nowhere – obvious and not-so-obvious biological models for ferrophobic surfaces

• Wilfried Konrad,
• Christoph Neinhuis and
• Anita Roth-Nebelsick

Beilstein J. Nanotechnol. 2022, 13, 1345–1360, doi:10.3762/bjnano.13.111

• walls should be much less prone to melting. The central idea was, therefore, to create a surface on the tuyère able to maintain an air layer that isolates the tuyère from the hot iron. For the persistence of the air layer, the following necessary conditions were identified: The surface should create a

• creating the air layer should not exceed the capillary length, that is, surface forces should dominate forces trying to distort the gas/liquid interface (e.g., gravitational forces). The straight top-down pathway: Identifying and following obvious biological models As a first step, it appeared to be quite

• (Figure 2). These are able to hold the resulting air layer for extended periods of time upon immersion. The interface is also resilient against perturbations. The “Salvinia effect” has considerable biomimetic potential, for instance, with respect to fuel reduction in maritime shipping [24][25] because an

Hierachical epicuticular wax coverage on leaves of Deschampsia antarctica as a possible adaptation to severe environmental conditions

• Elena V. Gorb,
• Iryna A. Kozeretska and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2022, 13, 807–816, doi:10.3762/bjnano.13.71

• projections. This, in turn, helps to keep an air layer between the wax particles under conditions of reduced water vapor. Moreover, superhydrophobic surfaces in combination with strong air flow can lead to newly formed ice particles being blown off, since the real contact area and, consequently, the adhesion

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

• Sepand Tehrani Fateh,
• Lida Moradi,
• Elmira Kohan,
• Michael R. Hamblin and
• Amin Shiralizadeh Dezfuli

Beilstein J. Nanotechnol. 2021, 12, 808–862, doi:10.3762/bjnano.12.64

A new bioinspired method for pressure and flow sensing based on the underwater air-retaining surface of the backswimmer Notonecta

• Matthias Mail,
• Adrian Klein,
• Horst Bleckmann,
• Anke Schmitz,
• Torsten Scherer,
• Peter T. Rühr,
• Goran Lovric,
• Robin Fröhlingsdorf,
• Stanislav N. Gorb and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2018, 9, 3039–3047, doi:10.3762/bjnano.9.282

• backswimmers (Notonecta sp.) are well known for their ability to retain air layers on the surface of their forewings (hemelytra). While analyzing the hemelytra of Notonecta, we found that the air layer on the hemelytra, in combination with various types of mechanosensitive hairs (clubs and pins), most likely

• serve a sensory function. We suggest that this predatory aquatic insect can detect pressure changes and water movements by sensing volume changes of the air layer under water. In the present study, we used a variety of microscopy techniques to investigate the fine structure of the hemelytra. Furthermore

• ., for drag reducing ship coatings [5]. Submerged backswimmers are covered with a thin air layer, in particular on their hemelytra (forewings) [4][11][12]. This air layer remains stable over long periods of time under both static and dynamic conditions [4][13][14][15]. To understand the mechanism that

Surfactant-induced enhancement of droplet adhesion in superhydrophobic soybean (Glycine max L.) leaves

• Oliver Hagedorn,
• Ingo Fleute-Schlachter,
• Hans Georg Mainx,
• Viktoria Zeisler-Diehl and
• Kerstin Koch

Beilstein J. Nanotechnol. 2017, 8, 2345–2356, doi:10.3762/bjnano.8.234

• micromanipulator. Prior to cryo-fixation, the liquid nitrogen was cooled down in a separate freezing chamber at 10−2 mbar to −210 °C in order to reduce the air layer between liquid nitrogen and the sample. After cryo-fixation, the samples were permanently stored in a precooled (−140 °C) and evacuated (5 × 10−4

Air–water interface of submerged superhydrophobic surfaces imaged by atomic force microscopy

• Markus Moosmann,
• Thomas Schimmel,
• Wilhelm Barthlott and
• Matthias Mail

Beilstein J. Nanotechnol. 2017, 8, 1671–1679, doi:10.3762/bjnano.8.167

• years, the Salvinia effect – the long term stabilization of an air layer on a submerged surface – has gained increasing interest. There is great potential for various technical applications utilizing this effect, for example, drag reduction, antifouling or anticorrosion applications, and underwater

• most complex plant surfaces is exhibited by the giant floating fern Salvinia molesta (Figure 1a,b). With its elastic egg-beater-like shaped trichomes and chemical heterogeneities [5], the fern is capable of maintaining a stable air layer underwater for several weeks. Another example is the backswimmer

• biological role models range from the millimeter (e.g., Salvinia) to the micrometer (e.g., Notonecta) scale. The shape of the air–water interface is of crucial importance for the diffusion and stability of the air layer under dynamic conditions. Konrad et al. set up a method allowing for the prediction of

Biological and biomimetic materials and surfaces

• Stanislav Gorb and
• Thomas Speck

Beilstein J. Nanotechnol. 2017, 8, 403–407, doi:10.3762/bjnano.8.42

• -structured, flexible, hairy structures on their outer surfaces which can trap an air layer under water for time spans of several minutes, days and even months. The biological importance of these air layers may be buoyancy, insulation, oxygen supply during diving and/or friction reduction during swimming and

The capillary adhesion technique: a versatile method for determining the liquid adhesion force and sample stiffness

• Daniel Gandyra,
• Stefan Walheim,
• Stanislav Gorb,
• Wilhelm Barthlott and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2015, 6, 11–18, doi:10.3762/bjnano.6.2

• cantilevers, reproducing the spring constants calibrated using other methods. Keywords: adhesion; AFM cantilever; air layer; capillary forces; hairs; measurement; micromechanical systems; microstructures; Salvinia effect; Salvinia molesta; sensors; stiffness; superhydrophobic surfaces; Introduction Surface

• approach. Prominent examples are the trichomes of the floating fern Salvinia molesta, which are responsible for the high air layer persistence of its leaves under water [1][2][3]. Artificial surfaces capable of retaining air under water have great potential in fluid transportation or as ship hull coatings

• [4][5] because of the significant drag reduction [6][7][8][9][10][11][12]. However, an essential requirement for the functionality of these surfaces is the persistence of the air layer [13][14][15]. As all of the highly engineered surfaces developed to date have failed in this respect [9][10][11][12

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

• Lars Heepe,
• Alexander E. Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

• negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L

Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces

• Matthias J. Mayser,
• Holger F. Bohn,
• Meike Reker and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2014, 5, 812–821, doi:10.3762/bjnano.5.93

• biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly

• sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m2 depending on differences in surface

• also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes. Keywords: air layer; biomimetic; drag reduction; functional surfaces; plastron; Salvinia effect; volume measurement; Introduction Since the description of hierarchically

Superhydrophobicity in perfection: the outstanding properties of the lotus leaf

• Hans J. Ensikat,
• Petra Ditsche-Kuru,
• Christoph Neinhuis and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 152–161, doi:10.3762/bjnano.2.19

• retention of the Cassie state with only partial contact between surface and water – an intrusion of water between the surface structures must be avoided. When the air layer is displaced by water, the water repellency is lost and the surface becomes wet (Wenzel state). The pressure which is necessary to

• material, which is too fragile for most technical applications. A different architecture is found on some species with hairy leaf surfaces. The water fern (some species of the genus Salvinia) and Pistia stratioides leaves retain a relatively thick air layer between hydrophobic hairs when submersed in water

• [24]. This provides sufficient buoyancy to avoid long-term submerging. Although superhydrophobic leaves retain an air layer when they are submersed, they are not designed for continuously living under water. All permanently submersed plant surfaces are hydrophilic without hydrophobic waxes [25

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• all cases a Cassie–Baxter regime [29] can be assumed so that the applied drop rests on an air layer in between the cover of surface protuberances. These hydrophobic structures enable the animal to trap an air film between the bottom surface and the tips of the surface protuberances. Air film