Innovative fountain pen writes on the nanoscale

Sm"The first practical fountain pen was invented in 1884 by Lewis Waterman.
Although pens with self-contained ink reservoirs had existed for more than a
hundred years before his invention, they suffered from ink leaks and other
troubles. Waterman solved these problems by inventing the capillary feed which
produced even ink flow. Now fountain pen history is repeating itself in the tiny
world of nanoscale writing.

Researchers at Northwestern University have
demonstrated writing at the sub-100 nanometer molecular scale in fountain-pen
fashion. They developed a novel atomic force microscope (AFM) probe chip with an
integrated microfluidic system for capillary feeding of molecular ink.

Dip-pen nanolithography (DPN) has been well-known for its capability of
high-resolution direct writing as a bottom-up nanofabrication technique. The DPN
technique exploits controlled deposition of molecules from an AFM tip to a
surface. However, the need of replenishing ink whenever exhausted has been a
limiting feature. Various attempts have been reported to overcome such a
drawback, but none of them reached molecular patterns with features smaller than
100 nanometers.

The Nanofountain Probe (NFP) developed by Horacio D.
Espinosa, professor of mechanical engineering, and his colleagues employs a
volcano-like dispensing tip and capillary fed solutions to enable sub-100
nanometer molecular writing. The NFP was microfabricated on a chip to be mounted
on commercially available AFMs. The device consists of an on-chip reservoir,
microchannels and a volcano-like dispensing tip. The microchannels are embedded
in the AFM cantilevers of the chip and the volcano dispensing tip has an annular
aperture to guide ink dispensing. The ink on the reservoir is driven through the
microchannel via capillary action to reach the dispensing tip. At present, the
smallest feature width achieved with the device is 40 nanometers…"


[Thanks Mike Shea!]