28 May 2020
"Periodic surface structure" is water and ice repellent, also repels up to 99% of dirt with rolling water droplets.
A project team from Technische Universität Dresden and the Fraunhofer Institute for Material and Beam Technology (IWS) structured an aluminum plate with a laser process such that water droplets no longer adhere and dirt particles can be removed from the surface — entirely without chemical cleaning agents or additional effort.
The scientific evidence of the self-cleaning effect has been published in Applied Surface Science.
For several years, scientists at TU Dresden and Fraunhofer IWS have been developing functionalized surfaces by means of laser-based manufacturing processes. Now, they have created a periodic surface structure that is not only water and ice repellent, but also removes dirt particles solely by rolling water drops.
"This material is used in many industrial branches—either in the automotive sector, aircraft construction or the food industry. The use of aggressive cleaning chemicals is particularly critical in food industry, as we naturally do not want to bring these chemicals in contact with our food," commented Stephan Milles, Ph.D. student at TU Dresden. In particular, the Dresden scientists studied the function of self-cleaning laser-structured aluminum.
A special camera was used to analyze the self-cleaning effect of the aluminum surfaces and filmed the process at 12,500 frames per second. Thomas Kuntze, scientist in the Microtechnology Technology Field at Fraunhofer IWS, explained, "In this way, we can perfectly see how a water drop can remove the dirt from the aluminum surface. This method is also suitable for understanding other processes, such as laser cutting and welding or additive manufacturing."
Video explains direct laser interference patterning (DLIP)
Watch the following TU Dresden / IWS video to see the development of an optical method to quantify the self-cleaning functionality of superhydrophobic aluminum surfaces. DLIP structures of 7.0 µm spatial period demonstrate a cleaning efficiency of up to 99% removal of the contaminating particles. High-speed recordings show the interaction between contamination and single water droplets.