ADVANCED MATERIALS & PROCESSES | MAY/JUNE 2024 12 LIGHT RESPONSIVE MATERIAL FOR SOFT MACHINES Scientists developed a type of soft material that can change shape in response to light, a discovery that could innovate soft machines for a variety of fields spanning robotics to medicine. Researchers at Lawrence Livermore National Laboratory (LLNL), Calif., created the novel material, a liquid crystal elastomer (LCE), by incorporating liquid crystals into the molecular structure of a stretchable material. Adding gold nanorods to the LCE material, scientists and engineers created photo-responsive inks and 3D-printed structures that could be made to bend, crawl, and move when exposed to a laser that causes localized heating in the material. The LLNL team used a direct ink writing technique to build a variety of light-responsive objects, including cylinders that could roll, asymmetric crawlers that could move forward, and lattice structures that oscillated. Researchers report the movement of the LCE material is driven primarily by a process known as photothermal actuation. Activated by the interaction between light, gold nanorods, and the LCE matrix, the process enables the printed structures to exhibit dynamic and reversible movements in response to external stimuli. Combining shape morphing with photoresponsivity, researchers say their new material could be used to create a soft machine capable of mimicking the movements and behaviors of living organisms. The team is now looking at starting a new strategic initiative at the lab to focus on autonomous materials and make advancements toward sentient materials. llnl.gov. INSECTS INSPIRE INVISIBILITY DEVICES Researchers at Penn State, State College, Pa., are looking to a common backyard insect for both inspiration and instruction for developing nextgen technology. The team precisely replicated the complex geometry of the tiny particles that leafhoppers secrete and use as a coating. Through the replication of these particles, called brochosomes, scientists elucidated a better understanding of how they absorb both visible and ultraviolet light. This could enable the development of bioinspired optical materials with applications ranging from invisible cloaking devices to coatings that can EMERGING TECHNOLOGY harvest solar energy, according to the researchers. The team found that the size of the holes in the brochosome that give it a hollow, soccer ball-like appearance is extremely important. The size is consistent across leafhopper species, regardless of body size. The brochosomes are roughly 600 nanometers (nm) in diameter, about half the size of a single bacterium, and the brochosome pores are around 200 nm. The researchers found the unique design of brochosomes serves a dual purpose— absorbing ultraviolet (UV) light, which reduces visibility to predators with UV vision, and scattering visible light, creating an anti-reflective shield against potential threats. Using advanced 3D-printing technology, researchers produced a scaledup version that was 20,000 nm in size. They accurately replicated the shape and morphology, as well as the number and placement of pores, to produce synthetic brochosomes that were large enough to characterize optically. Next, the researchers plan to explore additional applications for synthetic brochosomes, such as information encryption, where the structures could be used as part of an encoded system where data is only visible under certain light wavelengths. psu.edu. Liberty Reach Inc., Dexter, Mich., a supplier of 3D volumetric vision guidance systems for robot applications, changed its name to Liberty Robotics Inc. This reflects the company’s focus on machine vision and robotic guidance technologies. liberty-robotics.com. BRIEF Photo-responsive inks and movable 3D-printed structures were created by combining LLNL’s new liquid crystal elastomer with gold nanorods. Courtesy of Michael Ford. Brochosomes are hollow, nanoscopic, soccer ball-shaped spheroids with through-holes produced by a leafhopper. Courtesy of Lin Wang and Tak-Sing Wong/Penn State.
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