Writing With A Nanoscale Fountain Pen

By Roland Piquepaille

I'm sure that almost all of you have used a fountain pen. But imagine a pen drawing lines only 40 nanometers in width. Now, it can be done with the Nanofountain Probe (NFP) developed by scientists at Northwestern University. This innovative fountain pen "employs a volcano-like dispensing tip and capillary fed solutions to enable sub-100 nanometer molecular writing." But it needs to be mounted on an atomic force microscope (AFM) to be useful, so it probably is something you'll not find at your local drugstore for a while. However, this nanofountain probe could have applications for nanosensors, biotechnology and pharmaceuticals. Read more...

Here is the description of the Nanofountain Probe.

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.

Below are two images illustrating the technology, with associated comments from the researchers.

High-speed patterning over large areas with the resolution of dip-pen nanolithography (DPN) is the goal of this research by both removing the need for repeated dipping as in the DPN technique and by parallelizing the writing. Our strategy is to combine continuous ink feeding with the DPN technique using micromachining technology.

A novel AFM cantilever integrated with microchannels has been designed and microfabricated. Ink is supplied and stored in an on-chip reservoir, and subsequently fed through the microchannels by capillarity to reach a volcano-shape dispensing tip attached at the end of the cantilever. Batch-fabricated chips can be mounted into commercial atomic force microscopes.

The images above and their legends belong to Espinosa's Micro & Nanomechanics Laboratory and come from this page about the Nano Fountain Active Probe (NFAP).

But what will be able to do with these probes?

The standard microfabrication techniques used for the NFP chip -- an important feature of this development -- provides scalability to massively parallel arrays of probes and reservoirs for high throughput patterning with multiple molecular inks.

"The writing capability of such NFP arrays with chemical and bimolecular inks in fountain-pen mode is unique," said Espinosa. "We believe the technology will likely lead to many high-impact applications in the field of nanosensors, biotechnology and pharmaceuticals."

The research work has been published by Small, a new scientific journal from the Wiley & Sons group, under the name "A Nanofountain Probe with Sub-100 nm Molecular Writing Resolution."

Here are two links to the (empty) abstract and to the full paper (PDF format, 4 pages, 176 KB). It also contains other images illustrating the technology.

Here is the conclusion of the paper.

In summary, sub-100 nm molecular patterning has been achieved in fountain-pen writing mode with an AFM probe integrated with a volcano tip, microchannels, and a reservoir. The volcano tip has experimentally shown controlled transport of ink to avoid molecular flooding of substrates, ensuring high-resolution patterning. Standard microfabrication techniques were used, which allow the fabrication of massively parallel fountain probe arrays and integration of multiple reservoirs for sub-100 nm patterning over large areas with multiple inks. The devices have application in the fields of nanolithography, combinatorial nanochemistry, biosensors, nanodevices, and beyond.

Finally, if you want to become a partner of Northwestern University to develop such applications, please check their Technology Transfer Program about the High Speed Nano Fountain Pen.

Sources: Northwestern University news release, April 26, 2005; and various websites

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• Biotechnology
  
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