Surfaces with nanoscopic structures and high water repellence can exhibit self-cleaning properties. This “Lotus-Effect” was extensively investigated by Wilhelm Barthlott in the 1970s. The development of products with these properties started 15 years ago. Today, self-cleaning coatings, glasses, plastics and fabrics are available.
“Superhydrophobic” surfaces, i. e. extremely repellent surfaces, have besides their self-cleaning ability another interesting property: they are able to retain an air film under water. This film keeps plants like swimming ferns dry under water and offers an important technical application: a ship hull with a superhydrophobic coating would glide on air instead of being in contact with water. This reduces friction and saves fuel. This coating also helps against ship fouling.
Various biomimetic materials and their potential applications are presented in detail in the Thematic Series edited by Wilhelm Barthlott and Kerstin Koch.
A review article by Bharat Bhushan is the most accessed article in the Beilstein Journal of Nanotechnology and part of this series. Bhushan describes biomimetic surfaces which lead to reduced friction or behave extremely oil- or water-repellent, for example the shark skin: the tooth-like scales with ribbed grooves reduce the flow resistance in the water.
Snake Skin Leads to Improved Surfaces
The skin of the California King Snake served as a model for Martina Baum, Stanislav Gorb and other scientists in their research on increasing the durability of surfaces. They transferred the microstructure of the ventral scales of the snake to polymer surfaces. This enabled the scientists to reduce both friction and abrasion of the surfaces. This can be particularly advantageous for technical applications, since it can eliminate the need for lubricants.
The stick–slip phenomenon, which plays an important role in the movement of the snake, can also generate sound when it occurs with other materials: unintentionally with squeaky brakes, but welcome when guiding a bow across the strings of a violin.
Flying Fire Detectors
Fire loving insects need forest fires for their reproduction. After a fire, the females deposit their eggs under the bark of burnt trees, where the larvae are able to develop. To enable the species to survive, the beetles must be able to detect forest fires at large distances and are therefore equipped with smoke-sensitive antennae and special infrared sensors. These photomechanical sensors might serve well as models for the technical design of fire detectors, as Helmut Schmitz and other scientists presented in the Beilstein Journal of Nanotechnology.
Biological reactions can also serve as models for chemical synthesis. This was shown by scientists from the Comprehensive AIDS Research Center in Beijing. They synthesized katsumadain A, a compound isolated from herbs which are used in Chinese medicine. This compound represents an attractive lead structure for the anti-flu drug discovery.