1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 eras. The researchers’ new technique, called high-speed stress microscopy, provides a more quantitative way to study this phenomenon by directly measuring the force, stress, and pressure underneath liquid drops as they hit surfaces. The researchers found that the force exerted by a droplet actually spreads out with the impacting drop— instead of being concentrated in the center of the droplet—and the speed at which the droplet spreads out exceeds the speed of sound at short times, creating a shock wave across the surface. Each droplet behaves like a small bomb, releasing its impact energy explosively and giving it the force necessary to erode surfaces over time. The research could help engineers design more erosion-resistant surfaces for applications that must weather outdoor elements. Next, the team plans to study how different textures and materials change the amount of force created by liquid droplets. twin-cities. umn.edu. TESTING | CHARACTERIZATION SOLAR CELLS FOR SPACE A collaborative research team led by the University of Oklahoma, Norman, developed optimal conditions for testing perovskite solar cells for space applications. Perovskite solar cells are creating excitement in the photovoltaics community due to their rapidly increasing performance and their high tolerance to radiation. These properties suggest they could be used to provide power for space satellites and spacecrafts. The team measured the solar cells’ radiation hardness under different conditions. Using lower-energy particles, specifically protons, researchers confirmed that perovskites are radiation hard and that when damaged, they heal quickly. One area of application for the new protocol includes investigating perovskites’ use in permanent installations on the moon, specifically in whether lightweight flexible perovskites could be sent into space folded up and successfully deployed there, or even made on the moon. Future research could explore the utility of perovskite solar cells for space missions to planets like Jupiter that have an intense radiation environment or for satellite missions in polar orbits with high radiation levels. ou.edu. STUDYING DROPLET IMPACTS A new discovery about liquid droplets and their affect on hard surfaces could help engineers design better, more erosion-resistant materials. Using a newly developed technique, researchers from the University of Minnesota Twin Cities were able to measure hidden quantities such as the shear stress and pressure created by the impact of liquid droplets on surfaces, a phenomenon that has only ever been studied visually. Previously, droplet im- pact has only been analyzed visually using high-speed cam- Leica Microsystems will partner with Imperial College London to set up a dedicated imaging hub at the university, which will be equipped with advanced confocal and widefield microscopy systems. The hub will serve as a microscopy knowledge center in optical precision imaging for scientists and researchers, and will also create a space for joint research projects between the two organizations. leica-microsystems.com. Zeiss held a ribbon cutting on April 7 at its Zeiss Microscopy Customer Center Bay Area (ZMCC BA) in the company’s new high-tech building designed for customer and employee collaboration in Dublin, Calif. The ZMCC BA houses electron, light, and x-ray microscopes that are supported by resident application experts in life science, materials research, and electronics segments. zeiss.com. BRIEFS University of Oklahoma graduate student Sergio Chacon helps undergraduate researcher Rachel Penner set up perovskite solar cell measurements. The image shows the impact liquid droplets can make on a granular, sandy surface (left) versus a hard, plaster surface (right). Courtesy of Cheng Research Group, University of Minnesota.
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