Tag Archives: AFOSR

Desktop nanofabrication is in the laboratory but not in the marketplace yet

Another Chad Mirkin, Northwestern University (Chicago, Illinois, US), research breakthrough has been announced (this man, with regard to research,  is as prolific as a bunny) in a July 19, 2013 news item on ScienceDaily,

A new low-cost, high-resolution tool is primed to revolutionize how nanotechnology is produced from the desktop, according to a new study by Northwestern University researchers.

Currently, most nanofabrication is done in multibillion-dollar centralized facilities called foundries. This is similar to printing documents in centralized printing shops. Consider, however, how the desktop printer revolutionized the transfer of information by allowing individuals to inexpensively print documents as needed. This paradigm shift is why there has been community-wide ambition in the field of nanoscience to create a desktop nanofabrication tool.

“With this breakthrough, we can construct very high-quality materials and devices, such as processing semiconductors over large areas, and we can do it with an instrument slightly larger than a printer,” said Chad A. Mirkin, senior author of the study.

The July 19, 2013 Northwestern University news release (on EurekAlert), which originated the news item, provides details,

The tool Mirkin’s team has created produces working devices and structures at the nanoscale level in a matter of hours, right at the point of use. It is the nanofabrication equivalent of a desktop printer.

Without requiring millions of dollars in instrumentation costs, the tool is poised to prototype a diverse range of functional structures, from gene chips to protein arrays to building patterns that control how stem cells differentiate to making electronic circuits.

“Instead of needing to have access to millions of dollars, in some cases billions of dollars of instrumentation, you can begin to build devices that normally require that type of instrumentation right at the point of use,” Mirkin said.

The paper details the advances Mirkin’s team has made in desktop nanofabrication based upon easily fabricated beam-pen lithography (BPL) pen arrays, structures that consist of an array of polymeric pyramids, each coated with an opaque layer with a 100 nanometer aperture at the tip. Using a digital micromirror device, the functional component of a projector, a single beam of light is broken up into thousands of individual beams, each channeled down the back of different pyramidal pens within the array and through the apertures at the tip of each pen.

The nanofabrication tool allows one to rapidly process substrates coated with photosensitive materials called resists and generate structures that span the macro-, micro- and nanoscales, all in one experiment.

Key advances made by Mirkin’s team include developing the hardware, writing the software to coordinate the direction of light onto the pen array and constructing a system to make all of the pieces of this instrument work together in synchrony. This approach allows each pen to write a unique pattern and for these patterns to be stitched together into functional devices.

“There is no need to create a mask or master plate every time you want to create a new structure,” Mirkin said. “You just assign the beams of light to go in different places and tell the pens what pattern you want generated.”

Because the materials used to make the desktop nanofabrication tool are easily accessible, commercialization may be as little as two years away, Mirkin said. In the meantime, his team is working on building more devices and prototypes.

In the paper, Mirkin explains how his lab produced a map of the world, with nanoscale resolution that is large enough to see with the naked eye, a feat never before achieved with a scanning probe instrument. Not only that, but closer inspection with a microscope reveals that this image is actually a mosaic of individual chemical formulae made up of nanoscale points. Making this pattern showcases the instrument’s capability of simultaneously writing centimeter-scale patterns with nanoscale resolution.

Here’s a link to and a citation for the published paper,

Desktop nanofabrication with massively multiplexed beam pen lithography by Xing Liao, Keith A. Brown, Abrin L. Schmucker, Guoliang Liu, Shu He, Wooyoung Shim, & Chad A. Mirkin. Nature Communications 4, Article number: 2103 doi:10.1038/ncomms3103 Published 19 July 2013

This paper is behind a paywall. As an alternative of sorts, you might like to check out this March 22, 2012 video of Mirkin’s presentation entitled, A Chemist’s Approach to Nanofabrication: Towards a “Desktop Fab” for the US Air Force Office of Scientific Research.

Better night vision goggles for the military

I remember a military type, a friend who served as a Canadian peacekeeper (Infantry) in the Balkans, describing night-vision goggles and mentioning they are loud. After all, it’s imaging equipment and that requires a power source or, in this case, a source of noise. The Dec. 29, 2012 news item on Nanowerk about improved imaging for night vision goggles doesn’t mention noise but hopefully, the problem has been addressed or mitigated (assuming this technology is meant to be worn),

Through some key breakthroughs in flexible semiconductors, electrical and computer engineering Professor Zhenqiang “Jack” Ma has created two imaging technologies that have potential applications beyond the 21st century battlefield.

With $750,000 in support from the Air Force Office of Scientific Research (AFOSR), Ma has developed curved night-vision goggles using germanium nanomembranes.

The Dec. 28, 2012 University of Wisconsin-Madison news release, which originated the news item, describes the Air Force project and another night vision project for the US Department of Defense,

Creating night-vision goggles with a curved surface allows a wider field of view for pilots, but requires highly photosensitive materials with mechanical bendability-the silicon used in conventional image sensors doesn’t cut it.

…  Ma’s design employs flexible germanium nanomembranes: a transferrable flexible semiconductor that until now has been too challenging to use in imagers due to a high dark current, the background electrical current that flows through photosensitive materials even when they aren’t exposed to light.

“Because of their higher dark current, the image often comes up much noisier on germanium-based imagers,” says Ma. “We solved that problem.”

Ma’s dark current reduction technology has also been recently licensed to Intel.

In another imaging project, the U.S. Department of Defense has provided Ma with $750,000 in support of development of imagers for military surveillance that span multiple spectra, combining infrared and visible light into a single image.

“The reason they are interested in IR is because visible light can be blocked by clouds, dust, smoke,” says Ma. “IR can go through, so simultaneous visible and IR imaging allows them to see everything.”

Inexpensive silicon makes production of visible light imagers a simple task, but IR relies on materials incompatible with silicon.

The current approach involves a sensor for IR images and a sensor for visible light, combining the two images in post-processing, which requires greater computing power and hardware complexity. Instead, Ma will employ a heterogeneous semiconductor nanomembrane, stacking the two incompatible materials in each pixel of the new imager to layer IR and visible images on top of one another in a single image.

The result will be imagers that can seamlessly shift between IR and visible images, allowing the picture to be richer and more quickly utilized for strategic decisionmaking.

It’s impossible to tell from the description if this particular technology will be worn by foot soldiers or human military personnel but, in the event it will be worn,  it does well to remember that it will need a power source. Interestingly, the average soldier already carries a lot of weight in batteries (up to 35 pounds!) as per my May 9, 2012 posting about energy-harvesting textiles and the military.