These ideal natural properties can be imitated remarkably well now. Structuring a plastic or other surface is now possible by using an ultra fast femtosecond laser. PhD student Max Groenendijk of the Applied Laser Technology Group of the University of Twente presents remarkable results with this new technique.
The secret of the Lotus leaf can be found in numerous tiny pillars with a wax layer on top. Water drops are lifted by these pillars, get into a spherical shape and can simply not cover the surface. Dirt gets no chance to stick to the surface via water. The spherical drops roll off and take dirt particles with the, Again, nature proves to be a source of inspiration for the laser scientists of the University of Twente: they aimed at creating similar surfaces, but without having to use wax. They succeeded in that using an ultra fast femtosecond laser. The light pulses are so short that they can be seen as light ‘bullets’ with which the surface is bombed.
Max Groenendijk applies the laser in two separate steps. During the first step, the surface gets a fine ripple structure. This is caused by a special self organizing effect that works for almost all kinds of surfaces. Whenever the laser removes some material, a pattern of ripples is formed at the bottom. It is possible to influence this pattern with parameters like speed, intensity and polarization.
The second step is writing a pattern of perpendicular lines. What remains is an array of pillars. These pillars then already have the fine pattern caused by the first step. This double structure replaces the need to have wax on the pillars, and makes the surface highly hydrophobic. Treating surfaces directly would be to expensive, but by using a mold, series can be produced in an economic and easy way.
Silky feelingEven for materials that are quite hydrophobic by themselves, the structure can improve the properties drastically, Groenendijk concludes. Unlike in the unstructured, smooth situation, where droplets can still smear a little, the structured surface gives the spherical drops known from the Lotus plant.
The ‘look and feel’ of the material also changes, especially the ‘feel’: a surface that has been treated, feels like silk. This could be an added unique selling point, especially for trendy products.
To mimic the Lotus effect, several alternatives are available as well. It is possible to use a coating to make materials self cleaning, but an unstructured coating will never be as good as the new laser technique. Structured coatings could be an alternative, but applying a coating to a structured surface is another one Groenendijk is currently investigating, together with scientists of the Membrane Technology group. Both groups are part of the Institute for Mechanics, Processes and Control Twente (IMPACT) of the University of Twente: www.impact.utwente.nl
Wiebe van der Veen | alfa
Melting solid below the freezing point
23.01.2017 | Carnegie Institution for Science
An innovative high-performance material: biofibers made from green lacewing silk
20.01.2017 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
24.01.2017 | Earth Sciences
24.01.2017 | Life Sciences
24.01.2017 | Physics and Astronomy