(Funded by the U.S. National Science Foundation)
Researchers at Washington University in St. Louis have developed ultra-thin materials, called metasurfaces, that can amplify and interact with light regardless of its polarization. The metasurfaces are made of tiny nanoantennas that can both amplify and control light in very precise ways and could replace conventional refractive surfaces in eyeglasses and smartphone lenses. The polarization-independent metasurfaces have what’s known as a high quality factor, which means they trap light over a narrow band of resonant frequencies for a long time, generating a strong response to external stimuli.

(Funded by the U.S. National Science Foundation)
Researchers from Northwestern University have defined a method to tailor a sponge that is coated with nanoparticles to specific Chicago pollutants and then to selectively release them. In its first iteration, the sponge platform was made of polyurethane and coated with a substance that attracted oil and repelled water. The newest version is a highly hydrophilic (water-loving) cellulose sponge coated with nanoparticles tailored to other pollutants. The scientists found that by lowering the pH, metals flush out of the sponge. Once copper and zinc are removed, the pH is then raised, at which point phosphate comes off the sponge. Even after five cycles of collecting and removing minerals, the sponge worked just as well, and the resulting water had untraceable amounts of pollutants.

(Funded by the U.S. National Science Foundation, the U.S. Department of Defense, and the U.S. Department of Energy)
Physicists from the Massachusetts Institute of Technology, Harvard University, and the National Institute for Materials Science in Tsukuba, Japan, have directly measured superfluid stiffness for the first time in “magic-angle” graphene – materials that are made from two or more atomically thin sheets of graphene twisted with respect to each other at just the right angle. The twisted structure exhibits superconductivity, in which electrons pair up, rather than repelling each other as they do in everyday materials. These so-called Cooper pairs can form a superfluid, with the potential to move through a material as an effortless, friction-free current. “But even though Cooper pairs have no resistance, you have to apply some push, in the form of an electric field, to get the current to move,” says Joel Wang, one of the scientists involved in this study. “Superfluid stiffness refers to how easy it is to get these particles to move, in order to drive superconductivity.”

(Funded by the National Institutes of Health and the U.S. National Science Foundation)
A major challenge in self-powered wearable sensors for health care monitoring is distinguishing different signals when they occur at the same time. Now, researchers from Penn State and Hebei University of Technology in China have addressed this issue by developing a new type of flexible sensor that can accurately measure both temperature and physical strain simultaneously but separately, potentially enabling better wound healing monitoring. The sensor is made with laser-induced graphene, which forms when a laser heats certain carbon-rich materials in a way that converts their surface into a graphene structure.

(Funded by the U.S. National Science Foundation, the U.S. Department of Defense, and the National Institutes of Health)
Researchers from Caltech; the Beckman Research Institute at City of Hope in Duarte, CA; and the University of California, Los Angeles, have developed a technique for inkjet-printing arrays of special nanoparticles that enables the mass production of long-lasting wearable sweat sensors. These sensors could be used to monitor a variety of biomarkers – such as vitamins, hormones, metabolites, and medications – in real time, providing patients and their physicians with the ability to continually follow changes in the levels of those molecules. Wearable biosensors that incorporate the new nanoparticles have been successfully used to monitor metabolites in patients suffering from long COVID and the levels of chemotherapy drugs in cancer patients at City of Hope. “There are many chronic conditions and their biomarkers that these sensors now give us the possibility to monitor continuously and noninvasively,” says Wei Gao, one of the researchers involved in this study.