Biomimetics on the micro- and nanoscale – The 25th anniversary of the lotus effect

• Matthias Mail,
• Kerstin Koch,
• Thomas Speck,
• William M. Megill and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2023, 14, 850–856, doi:10.3762/bjnano.14.69

• properties: an adhesive elastomeric film with mushroom-shaped surface microstructures that mimic the adhesion system of animals. They show that this elastomer foil provides good air retention capabilities and is a promising material for the development of an economically and efficient biomimetic air

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

• Notonecta, show long term stable air retention even under hydrodynamic conditions. Therefore, they are ideal models for the development of technical biomimetic air retaining surfaces. Up to now, several prototypes of such surfaces have been developed, but none provides both, stable air retention and cost

• initially developed for a different purpose, due to their specific geometry at the microscale, are capable of stable air retention under water. We present first results concerning the capabilities of mushroom-shaped surface microstructures and show that this elastomer foil is able to stabilize a permanent

• 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

Biological and biomimetic surfaces: adhesion, friction and wetting phenomena

• Stanislav N. Gorb,
• Kerstin Koch and
• Lars Heepe

Beilstein J. Nanotechnol. 2019, 10, 481–482, doi:10.3762/bjnano.10.48

• Keywords: adhesion; air retention; contact mechanics; fluid transport; friction; functional gradients; wetting; This Thematic Series is the continuation of the previous series on the broad topic of biological and bioinspired materials and surfaces [1][2][3]. This collection of articles displays a current

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

• the air layer and assure stable air retention. Source: (b) modified after [11]. a) Left hemelytron of the backswimmer N. glauca. Four sections, defined by Wachmann [17], are shown. b) Scheme of the left hemelytron subdivided in 11 sections, according to Wachmann [17], and to variations in the hair

Collembola cuticles and the three-phase line tension

• Håkon Gundersen,
• Hans Petter Leinaas and
• Christian Thaulow

Beilstein J. Nanotechnol. 2017, 8, 1714–1722, doi:10.3762/bjnano.8.172

• in functional surfaces with effects like self-cleaning, drag reduction and air retention [10][11][12]. The field of superhydrophobic surfaces has made extensive use of biomimetic methods, where the imitation of natural surfaces provides the basis for artificial surfaces [9][13][14]. The exact nature

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

• , D-76344 Eggenstein-Leopoldshafen, Germany Institute of Crop Science and Resource Conservation (INRES) – Horticultural Science, University of Bonn, Auf dem Hügel 6, D-53121 Bonn, Germany 10.3762/bjnano.8.167 Abstract Underwater air retention of superhydrophobic hierarchically structured surfaces is

• open new possibilities for the investigation of air-retaining surfaces, specifically in terms of measuring contact area and in comparing different coatings, and thus will lead to the development of new applications. Keywords: AFM in liquid; air retention; atomic force microscopy; bionics; Salvinia

• effect; Introduction Air retention is one of the many fascinating aspects of superhydrophobic surfaces, offering promising new capabilities for technical applications [1]. Starting with the discovery of the lotus effect in 1997 [2], new fields in surface technology have been realized [3][4]. In recent

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

• upper leaf side of floating ferns of the genus Salvinia air layers are reported to persist from several days up to months [30][31][32]. Responsible for the long-term air retention in these organisms is a dense cover of elaborate, hydrophobic hairs on their surfaces (Figure 1). In Salvinia these hairs

• the creation of artificial surfaces with long-term air retention. Recent measurements by our project partners have revealed a drag reduction of 30% by such air retaining surfaces [27]. Applied on ships this would have a large impact on fuel consumption. Experimental Materials In order to test the

Hierarchically structured superhydrophobic flowers with low hysteresis of the wild pansy (Viola tricolor) – new design principles for biomimetic materials

• Anna J. Schulte,
• Damian M. Droste,
• Kerstin Koch and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 228–236, doi:10.3762/bjnano.2.27

• (“Lotus effect”) [4][5][6] or cause air retention under water (“Salvinia effect”) [7][8]. Superhydrophobic, self-cleaning surfaces possess a static contact angle (CA) equal to or above 150°, and a low hysteresis angle, where water droplets roll-off at surface inclinations equal to or below 10° [6][9]. One

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

• ]. Superhydrophobic surfaces which feature permanent air retention under water are found on animals (some birds, spiders and insects). An outstanding air-retention capability is found, for example, for the aquatic insect Notonecta glauca (‘backswimmer’) [26][27]. Here the water repellency is created by a two-level

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

• model organism for air retention, had about 60% of the initial area covered with air at a flow velocity of 2.25 m/s [35]. Obviously, the surface structure of the upper side of the elytra of the backswimmer is optimally adapted to hold an air film under hydrodynamic conditions. Beneath the dense

• : sternites; middle: underside of elytra; right side: upper side of elytra. Air retention [classes] of the submerged surfaces of Notonecta glauca vs time. All surfaces were treated with a hydrophobic coating. Air retention classes define the air retaining portion (X) of the surface, with 0: X = 0%; 1: 0% < X