(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.

(Funded by the U.S. Department of Energy and the National Institutes of Health)
Researchers from the University of California, Berkeley; the U.S. Department of Energy’s Lawrence Berkeley National Laboratory; and the University of Cambridge have developed a practical way to make hydrocarbons – molecules made of carbon and hydrogen – powered solely by the sun. The device combines a light absorbing “leaf” made from a high-efficiency solar cell material called perovskite, with a flower-shaped copper nanocatalyst, to convert carbon dioxide into useful molecules. Unlike most metal catalysts, which can only convert carbon dioxide into single-carbon molecules, the copper flowers enable the formation of more complex hydrocarbons with two carbon atoms, such as ethane and ethylene, which are key building blocks for liquid fuels, chemicals, and plastics.

(Funded by the U.S. National Science Foundation)
Researchers from the University at Buffalo; Central South University in Changsha, China; Shandong Normal University in Jinan, China; TU Wien in Vienna, Austria; the University of Salerno in Italy; and Sungkyunkwan University in Suwon, South Korea, have demonstrated that using thin two-dimensional (2D) materials, like the semiconductor molybdenum disulfide (MoS2), in combination with silicon can create highly efficient electronic devices with excellent control over how an electrical charge is injected and transported. The presence of the 2D material between the metal and silicon – despite the MoS2 being less than one nanometer thick – can change how electrical charges flow. “Our work investigates how emerging 2D materials can be integrated with existing silicon technology to enhance functionality and improve performance, paving the way for energy-efficient nanoelectronics,” says Huamin Li, the study’s lead author.