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

• Zoology, Christian-Albrechts-University of Kiel, Am Botanischen Garten 1–9, D-24118 Kiel, Germany 10.3762/bjnano.14.69 Keywords: biomimetic surfaces; hydrophobicity; lotus effect; Salvinia effect; superhydrophobicity; wettability; In 1997, Wilhelm Barthlott and Christoph Neinhuis published the paper

• “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

• actual applications. This was also the case with the lotus effect. Biomimetics was finally given a name in the second half of the last century, interestingly just as humankind was finally achieving Icarus’s dream of flying closer to the sun. The big push in the field came with the rapid development of

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

• ] and is known for more than thousand years [3], but after the Lotus effect publication [4], this research led to a paradigm shift in surface science [5] and was the starting point for novel technologies in surface science [5]. Today many products in forms of coatings, sprays and paints providing

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

• which a suitable biological model is sought. The “Lotus effect” belongs to the first class. It was identified by Wilhelm Barthlott and suggested (later accompanied by one of the co-authors, C. Neinhuis) as relevant for surface technology. The highly water-repellent plant cuticles, which are equipped

• 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

• “staying dry under water” for a much longer time [4][5]. Such surfaces usually feature functional structures that are larger than the wax crystals on the Lotus leaf (or other superhydrophobic leaf surfaces showing specially structured wax covers). Many of these surfaces possess hairs, such as those of the

Growing up in a rough world: scaling of frictional adhesion and morphology of the Tokay gecko (Gekko gecko)

• Anthony J. Cobos and
• Timothy E. Higham

Beilstein J. Nanotechnol. 2022, 13, 1292–1302, doi:10.3762/bjnano.13.107

• the Lotus Effect [11], the Gecko Effect has seen a surge in attention over the past couple of decades [12]. There are over 1000 species of geckos with adhesive capabilities, with multiple origins of the system [13][14]. However, much of what is known about gecko adhesion and its associated structures

Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders

• Sebastian Lifka,
• Kristóf Harsányi,
• Erich Baumgartner,
• Lukas Pichler,
• Dariya Baiko,
• Karsten Wasmuth,
• Johannes Heitz,
• Marco Meyer,
• Anna-Christin Joel,
• Jörn Bonse and
• Werner Baumgartner

Beilstein J. Nanotechnol. 2022, 13, 1268–1283, doi:10.3762/bjnano.13.105

• interaction and, thus, the design of a suitable surface structure to prevent sticking of an artificially nonwoven of nanofibers. Similar to the description of the Lotus effect [20][21][22][23], where the wettability of the hierarchical surface structure of the lotus leaf can be described with an energy

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

• fabricate such a surface featuring the lotus effect, solely through structuring, is hot pulling of a polymer surface. This technique provides the so-called nanofur, which consists of a polymer surface densely covered with a polymeric fur of extremely thin hair-like structures. Here, we present a continuous

• . These are well-suited for the cleanup of small oil spills. Keywords: hot embossing; lotus effect; nanofur; nanopads; oil spill cleanup; oil water separation; roll-to-roll; R2R; superhydrophobicity; Introduction Self-cleaning surfaces utilizing the famous lotus effect have gained significant importance

• unwanted dirt [5][6]. The lotus effect is commonly achieved by hierarchical nano- and micro-structuring of surfaces made from materials with low surface energy leading to very high contact angles (above 150°). This strategy is inspired by the lotus leaf [1] but can be found on many other surfaces in nature

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

• surface, the leaf of the lotus plant (Nelumbo nucifera Gaertn., Nelumbonaceae). Biomimetic surfaces The wettability properties of plant surfaces have often been a source of inspiration for the development of biomimetic materials. For example, biomimetic surfaces offer the possibility to study interfacial

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

• nanostructured ultrahydrophobic surfaces with self-cleaning ability, such as Lotus leaves and insect wing analogues [53][54][55], and the superhydrophobic air-retaining surfaces of Salvinia floating fern leaves and of the water bug Notonecta glauca [53][56]. Based on such blueprints, bioinspired anti-adhesion

• 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

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

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

• multifunctional wax coating on their surfaces made of branched ß-diketone tubules. ß-diketone tubules have a different size, shape, and chemical composition than the well-described nonacosanol tubules of the superhydrophobic leaves of lotus (Nelumbo nucifera). Until now the formation process of ß-diketone tubules

• 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

Nanostructured and oriented metal–organic framework films enabling extreme surface wetting properties

• Andre Mähringer,
• Julian M. Rotter and
• Dana D. Medina

Beilstein J. Nanotechnol. 2019, 10, 1994–2003, doi:10.3762/bjnano.10.196

• for their survival in extreme conditions [1][2][3][4]. In plants, the unique surface architecture of the lotus leaf enables superhydrophobic and self-cleaning properties for sustaining efficient photosynthesis, even in polluted environments [5][6][7]. In the realm of animals, mosquitos utilize an

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

• are devoted to surface-related effects in animal and plant surfaces, such as sandfish scales, wings of a ladybird beetle, tarsi of burying beetles, attachment devices of a sea star and a sea urchin, elytra of a backswimmer, leaves of an ice plant, and the wax layer of sacred lotus leaves. Seven of the

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

• surface structures; laser rescanning; steel; wettability; Introduction Complex structures found in nature often present properties that are attractive for applications in science and technology. The hydrophobicity found at the lotus leaf surface [1], the exceptional adhesion capability of gecko feet [2

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

• most famous nanostructure property in plants is the superhydrophobicity in lotus leaves that helps in self-cleaning and super-wettability of the leaves [193]. Many studies in the literature have suggested that stacks of nanostructures are responsible for the circular layer in plants and insects which

Bioinspired self-healing materials: lessons from nature

• Joseph C. Cremaldi and
• Bharat Bhushan

Beilstein J. Nanotechnol. 2018, 9, 907–935, doi:10.3762/bjnano.9.85

• . These types of surfaces, dependent on morphology and chemistry, are known as functional layers [28]. One prominent example of such behavior is the ability to self-clean, as can be seen in the lotus leaf in Figure 7D. The surface of the leaf causes water to roll off rather than slide due to the

• functionality to their surfaces to accomplish complex tasks without the need for movement. These replenishable surface layers consist of combinations of hierarchical morphology and/or chemistry to create different wetting behaviors and are referred to as functional coatings. In the well-known case of the lotus

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

• Biodiversity of Plants, University of Bonn, Venusbergweg 22, 53115 Bonn, Germany Institute of Experimental Physics, University of Wroclaw, pl. M. Borna 9, 50-204 Wrocław, Poland 10.3762/bjnano.9.45 Abstract The time dependence of the formation of lotus wax tubules after recrystallization from various

• ; crystallization; epicuticular wax; Lotus; Nelumbo nucifera; nonacosanol tubules; self-assembly; superhydrophobic; Introduction The plant cuticle, a cutin matrix embedded and covered by waxes provides a multitasking interface between plant and environment [1]. These waxes are either reside within the cutin layer

• superhydrophobicity of the wax coated surface. The time and temperature related formation of wax tubules has also been used to develop first artificial Lotus leaves for various wetting studies [24]. However, there are still a number of other factors that can affect tubule growth on HOPG. For example, the

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

• formation of a secondary structure on top of the convex epidermal cells, the interfacial contact area between the water droplet and the leaf surface is notably reduced, thus usually leading to extreme water repellency [39][40]. In contrast to other superhydrophobic plant surfaces like the lotus leaf

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

• ]. Generally, for the characterization of highly compressible surfaces by AFM, dynamic modes are difficult to apply [15][16][17]. The air–water interface of submerged lotus leaves was analyzed by magnetic alternating current mode [18], where the interface is “little disturbed” according to the authors. But

Biological and biomimetic materials and surfaces

• Stanislav Gorb and
• Thomas Speck

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

• , Germany, Freiburg Institute for Interactive Materials & Bioinspired Technologies (FIT), 79104 Freiburg, Germany 10.3762/bjnano.8.42 Keywords: adhesion; bio-inspired materials; biomimetics; interfaces; lotus effect; surfaces; This Thematic Series is a tribute to Wilhem Barthlott, a famous German botanist

• surfaces. From everyday life experience, we all know that during watering or rainfall, water rolls off the leaves of many plants in the form of spherical droplets leaving the leaves themselves entirely dry. This effect can be seen in an especially impressive manner on the leaves of the sacred lotus

• some biomimetic products, for example, the facade paint Lotusan® produced by Sto SEA Pte. [7] or the product Tegotop® 210 from Evonik Industries AG. The products are sold under the brand name Lotus-Effect® which has become a near synonym for functional, water-repellent surfaces in general. Without

Innovations from the “ivory tower”: Wilhelm Barthlott and the paradigm shift in surface science

• Christoph Neinhuis

Beilstein J. Nanotechnol. 2017, 8, 394–402, doi:10.3762/bjnano.8.41

• in materials science. Keywords: Wilhelm Barthlott; 70th birthday; self-cleaning surfaces; lotus-effect; Separation Most obviously, borders are meant to separate two or more entities from another (Figure 1). It might be our atmosphere separating us from space, an ocean separating two continents, a

• , self-cleaning surfaces nowadays are well known. The transfer and technical application have received several awards and the trademark “Lotus-Effect” has become a kind of synonym for functional water-repellent or even only hydrophobic surfaces. Follow-up investigations have been published in all major

• an environment with a much more biased research focus. In this particular example, one result of the research was the answer to the question of the systematic affinities of sacred lotus (Nelumbo nucifera). For the longest time scientist considered water lilies (Nymphaea) to be the closest relatives

When the going gets rough – studying the effect of surface roughness on the adhesive abilities of tree frogs

• Niall Crawford,
• Thomas Endlein,
• Jonathan T. Pham,
• Mathis Riehle and
• W. Jon P. Barnes

Beilstein J. Nanotechnol. 2016, 7, 2116–2131, doi:10.3762/bjnano.7.201

• specialised morphology allow the tree frogs to climb smooth vertical and overhanging surfaces. The attachment ability of tree frogs is affected by both surface chemistry and surface roughness. Hydrophobic leaves (such as those on lotus leaves [4]), could affect the capillary forces produced by the pad (which

• twigs [50]. We are thus building up a good understanding of both the underlying mechanisms and the ecology of tree frog adhesive mechanisms. But this study goes further: comparable to the drag reduction mechanisms of snake skin [51], the superhydrophobicity and self-cleaning mechanisms of lotus leaves

The cleaner, the greener? Product sustainability assessment of the biomimetic façade paint Lotusan^® in comparison to the conventional façade paint Jumbosil^®

• Florian Antony,
• Rainer Grießhammer,
• Thomas Speck and
• Olga Speck

Beilstein J. Nanotechnol. 2016, 7, 2100–2115, doi:10.3762/bjnano.7.200

• -cycle assessment (LCA); Lotus-Effect® technology; Lotusan®; product sustainability assessment (PROSA); Introduction In-depth analyses of functions found in biology and the systematic transfer of the respective operating principles into technical applications is the essential aim of biomimetics [1][2

• paint with self-cleaning properties. Results and Discussion Test of the criterion: Biomimetic product yes or no As suggested by Antony et al. [16], clarifying whether the superhydrophobic properties of double-structured rough plant surfaces like the one of the sacred lotus (Nelumbo nucifera) have been

• ]. Understanding of the functional principle and abstraction Within an abstraction phase the underlying functional principles of the biological model have to be translated into technology-compatible language [13][27]. In the present case the functional principle of the self-cleaning property of the lotus leaf can

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

• the past decade [5][6][7][8][9][10][11][12][13][14][15]. There are countless examples of functional surfaces inspired by plants, such as lotus leaves [5][13] and the pitchers of carnivorous plants [9][14] that can be used to tune the wetting/de-wetting properties of surfaces on various substrates

Three-gradient regular solution model for simple liquids wetting complex surface topologies

• Sabine Akerboom,
• Marleen Kamperman and
• Frans A. M. Leermakers

Beilstein J. Nanotechnol. 2016, 7, 1377–1396, doi:10.3762/bjnano.7.129

• surfaces is a key feature for many applications. The wetting properties of a surface depend on both the material and the surface topography. A famous example is the surface of a lotus leaf: Although the material of the leaf is hydrophilic (contact angle on a smooth substrate θY < 90°), the structured

Nanostructured superhydrophobic films synthesized by electrodeposition of fluorinated polyindoles

• Gabriela Ramos Chagas,
• Thierry Darmanin and
• Frédéric Guittard

Beilstein J. Nanotechnol. 2015, 6, 2078–2087, doi:10.3762/bjnano.6.212

• properties, characterized by extremely high water contact angles (θw) and low water adhesion or hysteresis (also known as “Lotus effect”), grows exponentially because of the importance for both the scientific and industrial community [1][2][3][4][5][6]. Superhydrophobic properties are quite common in nature