Patrick Winter

5 – Self-Cleaning Surfaces Using the Lotus Effect

Nature tends to have the best solutions. By copying the strategy of the lotus plant, a new way of cleaning and caring of surfaces is possible. The application of an aerosol or trigger spray containing a nanoparticle silicone wax blend is introduced as a semipermanent coating that prevents the attack of dirt to surfaces, allowing removal of nonpolar dirt with plain water. Also, with many plastic surfaces, experimental results gained so far are demonstrating the proof-of-concept: hydrophobic inorganic particles of properly selected size and shape are able to generate effects hitherto limited to biological structures. The special properties of lotus leaves are based on the additional hydrophobic microrelief on the surface of the leaf. The surface has, in addition to the hydrophobicity, a high degree of roughness, which causes an extremely high water repellency effect, much higher than that of only hydrophobic surfaces such as Teflon. The high surface tension of pure water is crucial for the Lotus effect. A reduction of the surface tension of water using solvents or surfactants may, therefore, destroy the effect. There are two commercial products available in the construction market: wall paint and self-cleaning tiles, both making use of the Lotus effect structure.