While 3-D patterning on the macroscale is a breeze, 3-D fabrication on the nanoscale is extremely limited, according to researchers at Johns Hopkins University (Baltimore). A self-assembly technique developed by the scientists, however, has enabled the creation of nanoparticles with nanolithography-patterned 3-D surfaces.
Hailing from the university’s departments of chemical and biomolecular engineering and chemistry, the research team has built on established 2-D lithography patterning methods to produce stable 3-D polyhedral nanoparticles as small as 100 nm. To make the boxes, the team carved the outline of six , 500-nm-wide square panels into a silicon wafer to form a cross-shaped mold. A nickel film was then deposited in the mold in order to make the box’s sides; tin grains were added to form hinges. Self-assembly of the panels into the cube shape was incited through the application of gases intended to etch away the silicon. Heating the panels then caused the hinges to melt, consequently merging the grains together and prompting the panels to be pulled upward to form the 3-D box shape.
This capability could contribute to the development of future electronic nanocircuits or have application in drug-delivery systems, according to the researchers.
