Earthworms are always clean, even if they come from moist, sticky soil. They owe this to a dirt-repellent, lubricating layer, which forms itself again and again on its skin. Researchers at INM have now artificially recreated this system of nature: They developed a material with a surface structure that provides itself with lubricant whenever pressure is applied. Because the lubricated material reduces friction and prevents the growth of microbes, scientists can envision numerous applications in industry and biomedicine.
The scientists recently published their results in the journal Advanced Materials.
The scientists developed a material made of soft plastic, with droplets of silicone oil as a lubricant at the inside of the material.
"When we put pressure on the material, the droplets change shape and migrate to the surface. The silicone oil then spreads evenly on the surface to a water and dirt-repellent sliding layer," explains Jiaxi Cui, head of the research group Switchable Microfluidics.
As the pressure decreases, the droplets will reform. In addition, the sliding layer can also be removed and formed again and again when pressure is applied to the material again. "So it reacts dynamically to pressure - like a" breathing "system," summarizes Cui.
The surface structure of the new material also plays an important role: "Again, we were inspired by the earthworm. Its skin surface is not smooth, but rough. That's what we took into account in our material and roughened the surface," explains Cui.
Precisely because of this roughness, a uniform lubricating film can form and adhere well. It depends on how friction-reducing the new material can behave.
"The surface structure is also important for the longevity of the lubricating effect: "We compared the sliding film on our "earthworm structures" with a sliding film on a smooth surface: our structures survive 10,000 cycles of friction, whereas sliding films on smooth structures have only 300 friction cycles," says the chemist Cui. It is precisely this combination of rough surface and the lubricant droplets inside that is special about the new material.
There are already some structures that reduce friction, including those that are modeled on the functioning of animal skins. Even systems that release lubricants themselves have been investigated by researchers. However, they all only work in a fluid environment so far.
"For the first time, we're introducing an application that reduces friction in a solid environment, and we've been inspired by the earthworm because it also glides through a solid environment, Earth," Cui says. Researchers can imagine many applications in industry or biomedicine, whenever a device has to glide smoothly through something solid.
INM – Leibniz Institute for New Materials, situated in Saarbrücken, is an internationally leading centre for materials research. INM conducts research and development to create new materials – for today, tomorrow and beyond. Research at INM is performed in three fields: Nanocomposite Technology, Interface Materials, and Bio Interfaces. INM is an institute of the Leibniz Association and has about 250 employees.
Your expert at INM:
Dr. Jiaxi Cui
Head Switchable Microfluidics
Zhao, Huaixia; Sun, Qiangqiang; Deng, Xu; Cui, Jiaxi. Earthworm-Inspired Rough Polymer Coatings with Self-Replenishing Lubrication for Adaptive Friction-Reduction and Antifouling Surfaces. Advanced Materials 2018, 30 (29), 1802141. https://doi.org/10.1002/adma.201802141
Dr. Carola Jung | idw - Informationsdienst Wissenschaft
New metamaterial morphs into new shapes, taking on new properties
12.09.2019 | California Institute of Technology
Reconfigurable electronics show promise for wearable, implantable devices
10.09.2019 | American Institute of Physics
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.
This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.
Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.
If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...
Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.
Beyond superconductors, there are few materials that can fulfill the requirements needed for making ultra-sensitive and fast terahertz (THz) detectors for...
A supersolid is a state of matter that can be described in simplified terms as being solid and liquid at the same time. In recent years, extensive efforts have been devoted to the detection of this exotic quantum matter. A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. The researchers report their results in Nature magazine.
In our everyday lives, we are familiar with matter existing in three different states: solid, liquid, or gas. However, if matter is cooled down to extremely...
A team headed by Prof. Steve Albrecht from the HZB will present a new world-record tandem solar cell at EU PVSEC, the world's largest international photovoltaic and solar energy conference and exhibition, in Marseille, France on September 11, 2019. This tandem solar cell combines the semiconducting materials perovskite and CIGS and achieves a certified efficiency of 23.26 per cent. One reason for this success lies in the cell’s intermediate layer of organic molecules: they self-organise to cover even rough semiconductor surfaces. Two patents have been filed for these layers.
Perovskite-based solar cells have experienced an incredibly rapid increase in efficiency over the last ten years. The combination of perovskites with classical...
10.09.2019 | Event News
04.09.2019 | Event News
29.08.2019 | Event News
13.09.2019 | Earth Sciences
13.09.2019 | Power and Electrical Engineering
13.09.2019 | Power and Electrical Engineering