It would make life a lot easier if the surfaces of window panes, corrosion coatings, or microfluidic systems could keep themselves free of water and other liquids. A new simulation software has been developed by researchers at the Fraunhofer Institute for Mechanics of Materials in Germany that shows how various liquids behave on different surfaces, whether they are flat, curved, or structured.
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 among liquid, surface, and air.
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. 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.
