Varying etching conditions influences the angles formed by the
panels in these nanoboxes. The left column is a close-up of the
tin hinge material. The other columns show the boxes at
different magnifications. The panels are patterned with the letters
“JHU” with line-widths of 15 nanometers. Credit: ACS/Nano Letters
Chemists have become very skilled at building 2-D nanostructures, but making 3-D patterned structures for drug delivery, electronics and other applications has proved more challenging. In particular, no one has been able to make 3-D structures with patterned surfaces.
David Gracias and Jeong-Hyun Cho of Johns Hopkins University in Baltimore have overcome this problem. They first made arrays of patterned, cross-shaped nickel structures on a silicon wafer, then added tin hinges. When placed in a plasma etching chamber, the flat structures folded up into cubes and released from the wafer. To make nanocubes as small as 100 nanometers a side, the researchers added another panel.
The work is described online in the journal Nano Letters, where the researchers write that it should apply to other polyhedral shapes as well.