Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Repelling the drop on top

01.06.2012
It would make life a lot easier if the surfaces of window panes, corrosion coatings or microfluidic systems in medical labs could keep themselves free of water and other liquids. A new simulation program can now work out just how such surfaces have to look for a variety of applications.

It’s raining cats and dogs and even the short run out to the car leaves your vision obscured by rain on your spectacles. There might soon be no need to reach for a cloth to wipe them off. If the surface of the lens resembled that of a lotus leaf, the drops would all fall off by themselves. The practicality of such self-cleaning surfaces is not limited to eyewear. Corrosion coatings would put up a better fight against rust without the tiny puddles of water that tend to collect on top of them.


Left: Micrometer-scale structured polystyrene surfaces for use with micro-fluids. Right: Static wetting of this type of surface with water – simulation and experiment. © Fraunhofer IWM

But exactly what characterizes surfaces that do the best job of cleaning themselves? Researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg have now developed simulation software that provides the answers. “Our simulation shows how various liquids behave on different surfaces, no matter if these are flat, curved or structured,” explains Dr. Adham Hashibon, project manager at the IWM. The program simulates the form the liquid droplets take on the surface, indicating whether the liquid distributes itself over the surface, or contracts to form droplets in order to minimize contact with the surface. The program is also able to calculate the flow behavior in terms of how liquids move across different surfaces, whereby the determinant factors at different scales of measurement are integrated, from atomic interactions to the impact of microscopic surface structure.

The software analyzes what goes on within a given droplet – how the individual water molecules interact with each other, how a droplet is attracted by the surface and how it resists the air. Researchers refer to a three-phase contact link between liquid, surface and air. “How liquid behaves on a surface is influenced by a great deal of parameters, including the surface characteristics of the material as well as its structure, but also by substances dissolved in the liquid. We have taken all this into account to different degrees of detail within the simulation so that we are able to clearly reproduce our experimental findings,” says Hashibon.

Improving microfluidic systems

The simulation is also useful in medical examinations. When doctors have to analyze tissue cells or parts of DNA, they often use microfluidic systems such as constant-flow cuvettes. Liquid containing dissolved substances is analyzed as it flows through tiny channels and minute chambers, and it is essential that no liquid whatsoever remains after the procedure has been completed. Any residual drops would then mix with a new sample and distort findings. The simulation will now be used to help optimize such microfluidic systems and to design surfaces so that as little liquid as possible gets left behind. “Our goal was to better understand and control the wetting behavior of liquids on structured surfaces,” says Hashibon. But that’s not all. This tool can also be used to implement a kind of traffic management system within the microfluidic system. When a channel splits into two, giving each fork a different surface structure makes it possible to separate the various components of the liquid, sending DNA molecules one way while other components are led along the alternative route. This technique can be used to heighten the concentration of certain molecules and is especially important, for instance, in raising the detection sensitivity of analysis techniques.

Dr. Adham Hashibon | Fraunhofer Research News
Further information:
http://www.fraunhofer.de/en/press/research-news/2012/june/repelling-the-drop-on-top.html

More articles from Materials Sciences:

nachricht Melting solid below the freezing point
23.01.2017 | Carnegie Institution for Science

nachricht An innovative high-performance material: biofibers made from green lacewing silk
20.01.2017 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists spin artificial silk from whey protein

X-ray study throws light on key process for production

A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...

Im Focus: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

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...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

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...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Breaking the optical bandwidth record of stable pulsed lasers

24.01.2017 | Physics and Astronomy

Choreographing the microRNA-target dance

24.01.2017 | Life Sciences

Spanish scientists create a 3-D bioprinter to print human skin

24.01.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>