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

• “Purity of the sacred lotus” [1] in which they described the superhydrophobic surfaces and the self-cleaning ability of some plants (the so-called “lotus effect”, see Figure 1). This paper led to a paradigm shift in surface sciences. It generated a lot of interest at the time and continues today to

• breadth of biological knowledge is still the foundation on which biomimetics is built. The paper by Mail et al. [17] “Dry under water: air retaining properties of large-scale elastomer foils covered with mushroom-shaped surface microstructures” focuses on superhydrophobic surfaces, not only on water

• prevent insects from climbing out. This surface structure is the opposite of adhesive surfaces. e) A dragonfly. Archetype for robotic applications but also known for their superhydrophobic and transparent wings. f) An example of the early evolution of superhydrophobic surfaces: the leaf of a ginkgo tree

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

• Holzgerlingen, Germany 10.3762/bjnano.13.113 Abstract Superhydrophobic surfaces are well known for most different functions in plants, animals, and thus for biomimetic technical applications. Beside the Lotus Effect, one of their features with great technical, economic and ecologic potential is the Salvinia

• superhydrophobic surfaces and self-cleaning properties are available on the market [1][6][7]. A most interesting feature of certain superhydrophobic surfaces is their ability to maintain a persistent air layer submerged under water. This ability is called Salvinia effect [5][8][9][10]. Due to the hydrophobic

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

• with hierarchically structured wax crystals, would represent “ready-made” models of superhydrophobic surfaces with versatile technical applications. The Lotus effect indeed proved to be attractive for applied sciences (as this special issue demonstrates), and its underlying physics was thoroughly

• persistent air layers for an extended time after immersion in water. Principally, superhydrophobic surfaces are commonly surrounded by air when immersed. However, the air body is not persistent enough for most applications and dissolves after some time, in contrast to surfaces that can be described as

• structure was sought, such as rigid pillars. In fact, various studies addressed the properties and application potential of this kind of technical surface structuring, for superhydrophobic surfaces as well as for surfaces with persistent air layers. Therefore, interfacial effects at surfaces covered with

Roll-to-roll fabrication of superhydrophobic pads covered with nanofur for the efficient clean-up of oil spills

• Patrick Weiser,
• Robin Kietz,
• Marc Schneider,
• Matthias Worgull and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2022, 13, 1228–1239, doi:10.3762/bjnano.13.102

• (KNMFi), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany 10.3762/bjnano.13.102 Abstract Superhydrophobic surfaces, which self-clean through rinsing with water, have gained significant importance during the last decades. A method to

• , too [7]. Multiple techniques exist to prepare self-cleaning surfaces. Direct laser writing and electron beam lithography have been employed successfully to create superhydrophobic surfaces. However, due to low writing speeds these approaches are not viable for surface areas larger than a few square

• millimeters [8][9]. Various (soft) lithography techniques have been employed to create superhydrophobic surfaces; however, these generally rely on copying surface information from a master (e.g., a lotus leaf) [9][10] and are therefore often limited in size. Superhydrophobic surfaces could also be prepared

Design of a biomimetic, small-scale artificial leaf surface for the study of environmental interactions

• Miriam Anna Huth,
• Axel Huth,
• Lukas Schreiber and
• Kerstin Koch

Beilstein J. Nanotechnol. 2022, 13, 944–957, doi:10.3762/bjnano.13.83

• inclined plane. The angle of inclination at which a droplet starts to roll off is called the TA α. Superhydrophobic surfaces with a low TA (α < 10°) and a small CAH have the ability to self-clean [9]. This property is also known as the Lotus effect, named after the best-known example of a self-cleaning

Bioselectivity of silk protein-based materials and their bio-inspired applications

• Hendrik Bargel,
• Vanessa T. Trossmann,
• Christoph Sommer and
• Thomas Scheibel

Beilstein J. Nanotechnol. 2022, 13, 902–921, doi:10.3762/bjnano.13.81

• cells but to even display antiviral attachment properties [58]. Superhydrophobic surfaces inspired by the Lotus-effect® (>150° contact angle) have been found to diminish bacterial adhesion due to reduced protein surface adsorption [59][60][61]. Superhydrophobicity relies on the combination of chemical

• obtained from fluorinated silica colloids, thin film deposition of silicone elastomers or nanoengineered superhydrophobic surfaces of Teflon®-coated aluminium [63][64][65]. Superhydrophobic surfaces have also been reported to be unfavorable for mammalian cell attachment and growth. This may be due to the

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

• ., Asclepiadaceae and Cactaceae) [15], plays a crucial role in the protection from water loss. Biomimetic potential Since the discovery of the lotus effect [43], different properties of superhydrophobic surfaces in plants, which are highly relevant for modern technologies, such as self-cleaning, fluid drag

• 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

A review on slip boundary conditions at the nanoscale: recent development and applications

• Ruifei Wang,
• Jin Chai,
• Bobo Luo,
• Xiong Liu,
• Jianting Zhang,
• Min Wu,
• Mingdan Wei and
• Zhuanyue Ma

Beilstein J. Nanotechnol. 2021, 12, 1237–1251, doi:10.3762/bjnano.12.91

• . Investigating the effect of gas bubbles on the effective slip length is also of great value especially in the design and optimization of superhydrophobic surfaces, which have lots of applications due to their superlubricating potential [112][113][114]. The liquid flow behavior on such surfaces can be described

• superhydrophobic surfaces. For periodic deep grooves on superhydrophobic Cassie textures or even for more complex 2D textures, the classical “gas cushion” model does not apply. Instead, a general gas cushion model proposed by Nizkaya et al. can better evaluate the local slip length at the liquid–gas interface [115

• changed to induce a large slip length. Superhydrophobic surfaces are just such examples and liquids can experience extremely low drag resistance when flowing on those surfaces. Daniello et al. found that apart from the laminar flow regime, drag can still be reduced on superhydrophobic surfaces even in the

Self-assembly of Eucalyptus gunnii wax tubules and pure ß-diketone on HOPG and glass

• Miriam Anna Huth,
• Axel Huth and
• Kerstin Koch

Beilstein J. Nanotechnol. 2021, 12, 939–949, doi:10.3762/bjnano.12.70

• structure [13][18]. Secondary alcohol tubules evolved in all major groups of land plants and design durable superhydrophobic surfaces (e.g., the Lotus Effect). In vitro recrystallization experiments with single wax components of these tubules showed that tubules were formed by secondary alcohols plus at

An investigation on the drag reduction performance of bioinspired pipeline surfaces with transverse microgrooves

• Weili Liu,
• Hongjian Ni,
• Peng Wang and
• Yi Zhou

Beilstein J. Nanotechnol. 2020, 11, 24–40, doi:10.3762/bjnano.11.3

• [7][8][9], the injection of gas to modify the turbulent boundary characteristics [10], and the fabrication of superhydrophobic surfaces to reduce the adhesion [11]. However, the application of polymer additives is not economic and the antidrag performance of additives is also instable under some

Rapid, ultraviolet-induced, reversibly switchable wettability of superhydrophobic/superhydrophilic surfaces

• Yunlu Pan,
• Wenting Kong,
• Bharat Bhushan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2019, 10, 866–873, doi:10.3762/bjnano.10.87

• understanding, the effect of the trimethoxy(alkyl)silane concentration on the number of recycle cycles was investigated. Keywords: superhydrophilic surfaces; superhydrophobic surfaces; switchable wettability; TiO2; trimethoxy(alkyl)silane; UV illumination; Introduction Wettability is an important property of

Novel reversibly switchable wettability of superhydrophobic–superhydrophilic surfaces induced by charge injection and heating

• Xiangdong Ye,
• Junwen Hou and
• Dongbao Cai

Beilstein J. Nanotechnol. 2019, 10, 840–847, doi:10.3762/bjnano.10.84

• for converting superhydrophobic surfaces into superhydrophilic surfaces after only 10 min of ultraviolet irradiation. Gao et al. [6] prepared 18 alkyltrichlorosilane-modified TiO2 films for the reversible switching between superhydrophilicity and superhydrophobicity of a wood surface. Feng et al. [7

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

• . Keywords: mechanoreceptor; Notonecta sensor; pressure sensor; Salvinia effect; superhydrophobic surfaces; Introduction The surfaces of animals and plants are interfaces between the organisms and the environment. Since animals and plants inhabit many different environments, it is not surprising that over

• adhesive pads [6] or the structural colors of Morpho menelaus [7]. Superhydrophobic surfaces are also important in the above context. Several plants and animals, which can maintain stable air layers while submerged (Salvinia effect [8]), have been analyzed. Especially the floating ferns of the genus

Biomimetic surface structures in steel fabricated with femtosecond laser pulses: influence of laser rescanning on morphology and wettability

• Camilo Florian Baron,
• Alexandros Mimidis,
• Daniel Puerto,
• Evangelos Skoulas,
• Emmanuel Stratakis,
• Javier Solis and
• Jan Siegel

Beilstein J. Nanotechnol. 2018, 9, 2802–2812, doi:10.3762/bjnano.9.262

• (black square). Points plotted with CA values above 150° correspond to superhydrophobic surfaces that did not allow the positioning of the droplet (no CA could be measured in those cases). The top row of micrograph illustrates a time sequence of such a case, summarized in four stages: approaching

• distinguish between surfaces with different wetting behaviors. Superhydrophobic surfaces in yellow (CA > 150°), hydrophobic surfaces in blue (150° > CA > 90°) and hydrophilic surfaces in grey (90° > CA > 10°). The CA of untreated steel is 103° indicated by a solid line. A) Experimental setup, employing a high

Review on nanoparticles and nanostructured materials: history, sources, toxicity and regulations

• Jaison Jeevanandam,
• Ahmed Barhoum,
• Yen S. Chan,
• Alain Dufresne and
• Michael K. Danquah

Beilstein J. Nanotechnol. 2018, 9, 1050–1074, doi:10.3762/bjnano.9.98

Kinetics of solvent supported tubule formation of Lotus (Nelumbo nucifera) wax on highly oriented pyrolytic graphite (HOPG) investigated by atomic force microscopy

• Sujit Kumar Dora,
• Kerstin Koch,
• Wilhelm Barthlott and
• Klaus Wandelt

Beilstein J. Nanotechnol. 2018, 9, 468–481, doi:10.3762/bjnano.9.45

• . We demonstrate how these different factors affect the tubule growth, in order to gain greater insight into those factors that can affect the tubule growth and which can subsequently be used to manipulate these wax structures on HOPG, e.g., in order to model specific superhydrophobic surfaces

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

• a composite wetting state, where water wets only the tops of surface features, without wetting the substrate in between [15]. The composite wetting state assumed by Cassie and Baxter is well known in a range of other natural superhydrophobic surfaces [9]. The stability of the composite wetting state

• values of f, the resulting range is 118–157°. Direct measurement of the contact angles of Collembola cuticles are scarce, but their wetting behavior is variously described as “non-wetting” [30][33] “anti-wetting” [2][33] and “unwettable” [1]. The common classification of “superhydrophobic” surfaces

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

• 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

Surface roughness rather than surface chemistry essentially affects insect adhesion

• Matt W. England,
• Tomoya Sato,
• Makoto Yagihashi,
• Atsushi Hozumi,
• Stanislav N. Gorb and
• Elena V. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1471–1479, doi:10.3762/bjnano.7.139

• rough superhydrophobic surfaces. Base coats were first deposited onto UV-cleaned Si substrates (2 × 2 cm2 and 5 × 5 cm2), then dried in air at room temperature (25 ± 2 °C) for more than 30 min. Next, topcoats were deposited onto the surfaces and cured at 100 °C for 24 h, hereafter referred to as Never

• very easily and would roll off at very low tilt angles of the substrate because of their extremely large CAs and low CA hysteresis (Δθ = 2–5°). On the other hand, while the static/dynamic CAs of smooth C10-hybrid surfaces were considerably lower than those of the superhydrophobic surfaces, the CA

Automatic morphological characterization of nanobubbles with a novel image segmentation method and its application in the study of nanobubble coalescence

• Yuliang Wang,
• Huimin Wang,
• Shusheng Bi and
• Bin Guo

Beilstein J. Nanotechnol. 2015, 6, 952–963, doi:10.3762/bjnano.6.98

• hydrophobic/superhydrophobic surfaces [22][23][24][25][26][27]. The interaction between NBs and sample surfaces supporting them was also recently investigated. A phenomenon of NB-induced nanoindentions was reported by Wang et al. on an ultrathin polystyrene (PS) film in water [8], and was further confirmed by

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

Aquatic versus terrestrial attachment: Water makes a difference

• Petra Ditsche and
• Adam P. Summers

Beilstein J. Nanotechnol. 2014, 5, 2424–2439, doi:10.3762/bjnano.5.252

• where terrestrial mechanics might apply. For example, when spiders bring with them a ball of air as they dive beneath the surface, or when two superhydrophobic surfaces interact underwater. Therefore, the first task that we face is to make clear what we mean as we try to distinguish between these two

• surfaces [68][72]. Many superhydrophobic surfaces are known for their ability to hold an air film under water for a varying time span [73][74][75]. Therefore, these surfaces could hold micro bubbles that serve as cavitation nucleating sites as in seawater. Whether this effect would occur after a long-time

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

• Yunlu Pan,
• Bharat Bhushan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2014, 5, 1042–1065, doi:10.3762/bjnano.5.117

• length [17]. Very large slip lengths were found on superhydrophobic surfaces [6][27][28][29][30][31]. However, more convenient methods that can increase the boundary slip length without changing surface or solution are still needed. Nanobubbles, which are bubbles with dimensions of 5–100 nm in height and

• 50–800 nm in diameter at the interface of solid and liquid, were found on some hydrophobic and superhydrophobic surfaces [14][16][32][33][34][35][36][37][38]. The nanobubbles change the interface of solid and liquid and therefore are believed to affect the drag of liquid flow. Due to the high Laplace

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

• of Freiburg, Schänzlestrasse 1, 79104 Freiburg im Breisgau, Germany 10.3762/bjnano.5.93 Abstract Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect) are of high interest for

• structured, superhydrophobic, self-cleaning plant surfaces (Lotus-effect) [1][2] there has been an increasing interest in superhydrophobic surfaces [3][4][5]. Superhydrophobicity describes the extreme repellence of water by a surface. The level of water repellence is usually described by the contact angle

• present a new method to measure the volume of air retained by biological and artificial superhydrophobic surfaces quantitatively. Air layers of four Salvinia species and of well defined replicas were analysed. Results and Discussion Air volume on wafer replica For the validation of the method we use the

En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays

• Slawomir Boncel,
• Sebastian W. Pattinson,
• Valérie Geiser,
• Milo S. P. Shaffer and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2014, 5, 219–233, doi:10.3762/bjnano.5.24

• composites of enhanced thermal and electrical conductivity [18][19], superhydrophobic surfaces [20], separation membranes [21] and sensors [22]. As for aligned N-CNT arrays, to mention the most recent and prominent applications, they have shown to be suitable catalysts for the reduction of oxygen in alkaline