Apr 5, 2011
Tip measures nanochannel kinetics in thin water films
Researchers in Brazil have fabricated nanochannels by scanning an AFM tip on water deposits on a mica surface at room temperature. The time evolution of the channel profile is an important factor in the application of this method as a fabrication technique. To find out more, the nanostructures and interfaces group based at UNICAMP has studied the structure and transport properties of water layers that adjoin a charged solid, such as a mica surface. The team presented its findings in the journal Nanotechnology.
By analysing the shape and morphology of the material removed during channel fabrication, the channel profile was shown to vary on the scale of a tenth of a second, far too slow for a liquid rearrangement. Therefore, there is no liquid at the tip/substrate interaction region, but only an aggregate that behaves as a solid-like structure. The results show conclusively that, because water behaves as an ice-like material at these dimensions, only gas can be transported in 10 nm radius structures.
The fabricated channels could be used to pattern micro-fluidic chips because they are stable under fixed temperature and humidity. A three-dimensional view of a fabricated grating together with a schematic diagram of the nanochannel formation process are shown in the image.
A full discussion of the results can be found in the journal Nanotechnology.
About the author
Omar Teschke is professor and head of the Grupo de Nanoestruturas e Interfaces, Departamento de Fisica Aplicada, Instituto de Fisica, UNICAMP, SP, Brazil.