Scientists at Northwestern University near Chicago have found a way to turn a common laboratory tool into the world's finest writing instrument, capable of drawing lines just a few molecules wide and one molecule thick.
The instrument is an atomic force microscope, or AFM, commonly used to transfer molecules onto surfaces with extremely high precision. But AFMs have an irritating problem for their users: The tip tends to attract moisture from the air and form a tiny drop between the tip and the substrate, or surface to be drawn on.
Northwestern chemistry professor Chad A. Mirkin and colleagues write in the Jan. 29 edition of the journal Science that they turned the bug into a feature, harnessing the flow of water molecules between tip and substrate to pass the chemical "ink" through a super-tiny capillary channel to the surface. Mirkin said his technique has very old roots: "It's a miniaturization of a 4,000-year-old technology, the dip pen."
The research could have practical implications for nanotechnology, the science of incredibly tiny objects -- both in testing nanotech concepts and in creating linkages between the nano-sized objects and more conventional microscopic equipment.
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