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

• superhydrophobic, low adhesive surface design, which combines the hierarchical structuring of petals with a wetting behavior similar to that of the lotus leaf. Keywords: anti-adhesive; petal effect; petal structures; polymer replication; superhydrophobic; Introduction Plant surfaces provide a large diversity of

• “petal effect” and are anti-adhesive for water droplets. It is well known that hierarchical surface architecture represents optimized structures for superhydrophobic surfaces [11][33][34][35][36]. Based on the data presented here, we can describe two main superhydrophobic surface architectures for plant

Functional morphology, biomechanics and biomimetic potential of stem–branch connections in Dracaena reflexa and Freycinetia insignis

• Tom Masselter,
• Sandra Eckert and
• Thomas Speck

Beilstein J. Nanotechnol. 2011, 2, 173–185, doi:10.3762/bjnano.2.21

• occupied and trap solar energy in an efficient way (e.g., [5]). However, these benefits are coupled with disadvantages such as increased magnitude and complexity of mechanical loads. Therefore, structural and mechanical adaptation on different hierarchical levels can be observed both in main stems as well

• for Textile Technology and Process Engineering Denkendorf, the Institute of Lightweight Structures and Polymer Technology of the TU Dresden as well as the Botanical Garden of the TU Dresden [27][28][29][30][31]. In this project the hierarchical organisation of branch–stem-junctions of arborescent

• monocotyledons and columnar cacti is analysed and different biomechanical tests are performed on these plants in order to determine the mechanical parameters of stems, branches, branch–stem-junctions and the different constituent tissues in different directions. This allows for simulation of hierarchical

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

• the aquatic environment – some of the leaves float occasionally on the water surface – the stomata are located in the upper epidermis. The lower epidermis consists of convex cells covered with wax tubules and contains only few stomata. The upper epidermis features the distinctive hierarchical

• structure consisting of papillae with a dense coating of agglomerated wax tubules, which is the basis for the famous superhydrophobicity (Figure 1). However, a hierarchical surface structure which induces strong water repellency and contact angles above 150° is not a special feature of lotus leaves. It has

• regenerate damaged or lost waxes. Conclusion It is true that lotus exhibits outstanding water repellency on the upper side of its leaves. The basis of this behaviour is the hierarchical surface structure. In comparison to other species with a hierarchical surface structure composed of papillae and wax

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

• through water, but most of the time it supports itself from underneath against the water surface with both pairs of fore legs and the tip of the abdomen [26]. The surface of the elytra is covered by a hierarchical structure of larger setae and very small microtrichia. Balmert et al. hypothesized that the

• , a pure microtrichia structure and a hierarchical structure with setae and microtrichia (Figure 2). On the abdominal sternites a pure setae structure can be observed. About 2,300 setae per mm2 cover the surface up to a height of approximately 30 µm. The basis of these setae points in the caudal

• in the living animal, the upper side stays in direct contact with the water. It therefore may have developed further adaptations to stabilize the air film. Obviously, the hierarchical double structure of the upper side of the elytra with a dense microtrichia cover and two different kinds of setae is

Biomimetics inspired surfaces for drag reduction and oleophobicity/philicity

• Bharat Bhushan

Beilstein J. Nanotechnol. 2011, 2, 66–84, doi:10.3762/bjnano.2.9

• , nanodevices, and processes which provide desirable properties. Hierarchical structures with dimensions of features ranging from the macroscale to the nanoscale are extremely common in nature and possess properties of interest. There are a large number of objects including bacteria, plants, land and aquatic

• animals, and seashells with properties of commercial interest. Certain plant leaves, such as lotus (Nelumbo nucifera) leaves, are known to be superhydrophobic and self-cleaning due to the hierarchical surface roughness and presence of a wax layer. In addition to a self-cleaning effect, these surfaces with

• waxes on lotus leaves exist as tubules [10][11]. Water droplets on these hierarchical structured surfaces readily sit on the apex of the nanostructures because air bubbles fill the valleys of the structure under the droplet (Figure 1a). Therefore, these leaves exhibit considerable superhydrophobicity