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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 | N O V E M B E R / D E C E M B E R 2 0 2 1 6 SHAPESHIFTING LIQUID CRYSTAL Physicists at Case Western Reserve University, Cleveland, and Tufts Univer- sity, Medford, Mass., report changing the shape of a flat liquid crystal surface without applying any local stimulus. “This is a groundbreaking accomplish- ment and could prove to be the start- ing point for future applications—many which we cannot yet imagine,” says Case physics professor Charles Rosen- blatt, one of the lead researchers. Pre- viously, scientists who have similarly transformed the shape of liquid crys- tal surfaces have done so by using heat, light, or another force applieddirectly to the undisturbed surface. This team took a new path, changing the liquid crystal surface simply by placing a patterned substrate on the opposite side of a thin film in which the molecules are aligned in parallel. Future applications could lead to improvements in microchips and development of fluid microscop- ic tools that could perform repairs less invasively, flowing back into their orig- inal shape after use. In the new work, the team manipulated what Rosenblatt calls “an orientable Newtonian liquid,” a nematic liquid crystal that behaves predictably when an outside stimulus is RESEARCH TRACKS applied. The nematic phase consists of cigar-shaped molecules arranged par- allel to each other, but which can flow like water. Consider that when a glass is filled with water, the surface where the air and water meet is essentially flat. In this case, the researchers forced the liquid crystal/air interface to change shape by exploiting the orientability of the molecules that comprise the liq- uid crystal. To do that, the team placed the patterned substrate on the oppo- site side of a thin nematic film. By doing so, they were able to control the alignment of molecules throughout the material. This resulted in a predetermined “bumpy” surface where the liquid and air meet—accom- plished without any stimu- lus at the surface and with- out any control beyond the patterned bottom of the pool far from the surface. The rela- tive change was as much as a 30-70% increase in height from a flat surface. Next, the team will next work on fine-tuning the surface shape by applying an external elec- tric field and varying temper- ature. case.edu. Liquid crystals in the nematic phase, in which their rod-like molecules line up in a disorderly yet parallel manner. Courtesy of Wikimedia Commons. NEW SILICON CARBIDE FABRICATION FACILITY Engineering researchers at the University of Arkansas, Fayetteville, re- ceived $17.87 million from the Nation- al Science Foundation to build and op- erate a national silicon carbide research and fabrication facility. The team is led by Prof. Alan Mantooth. The open ac- cess center will fill a void in U.S. produc- tion of integrated circuits made with silicon carbide. Currently, all silicon car- bide fabrication facilities in the U.S. are for internal use only, so U.S. research and development of silicon carbide in- tegrated circuits relies on international fabrication. The new center will provide do- mestic opportunities for prototyping, proof-of-principle demonstrations, and device design. It will be the only openly accessible fabrication facility of its kind in the U.S. with services available to ex- ternal researchers. The aim is to provide integrated circuits, sensors, and devic- es for military and industrial applica- tions such as solar inverters, electron- ics for cars, and systems used in heavy equipment and space exploration. uark.edu. Alan Mantooth at the University of Arkansas, future home of an open access domestic silicon carbide fabrication facility.