Science

“Mini Lisa” demonstrates potential of nanomanufacturing technique

“Mini Lisa” demonstrates poten...
Professor Jennifer Curtis "painting" the 30-micron Mini Lisa
Professor Jennifer Curtis "painting" the 30-micron Mini Lisa
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Mini Lisa is a 30 x 40 micron gray-scale QVGA rendering of Leonardo's Mona Lisa
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Mini Lisa is a 30 x 40 micron gray-scale QVGA rendering of Leonardo's Mona Lisa
On the left appears a grey scale image of the real Mona Lisa, while on the right appears an image showing the variations in heat required to create Mini Lisa
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On the left appears a grey scale image of the real Mona Lisa, while on the right appears an image showing the variations in heat required to create Mini Lisa
The TCNL atomic force microscope in action
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The TCNL atomic force microscope in action
TCNL image of Ansel Adams' Rose and Driftwood, illustrating how the heated cantilever and tip render the image
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TCNL image of Ansel Adams' Rose and Driftwood, illustrating how the heated cantilever and tip render the image
Professor Jennifer Curtis "painting" the 30-micron Mini Lisa
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Professor Jennifer Curtis "painting" the 30-micron Mini Lisa
Schematic of a simple atomic force microscope with a heated cantilever and tip
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Schematic of a simple atomic force microscope with a heated cantilever and tip
View gallery - 6 images

Arguably the world’s most famous painting, da Vinci's Mona Lisa has now been copied onto the world’s smallest canvas at the Georgia Institute of Technology. Associate Professor Jennifer Curtis' "Mini Lisa" is one-third the width of a human hair, with details as small as one-eighth of a micron. Mini Lisa demonstrates the flexibility of a new nanolithography technique that can vary the surface concentration of molecules on very small portions of a substrate.

Mini Lisa was rendered using an atomic force microscope and a new process called ThermoChemical NanoLithography (TCNL).

Mini Lisa is a 30 x 40 micron gray-scale QVGA rendering of Leonardo's Mona Lisa
Mini Lisa is a 30 x 40 micron gray-scale QVGA rendering of Leonardo's Mona Lisa

The Georgia Tech team formed the image pixel by pixel. The cantilever and tip of an atomic force microscope were heated, and then lowered to the desired location of a pixel.

Schematic of a simple atomic force microscope with a heated cantilever and tip
Schematic of a simple atomic force microscope with a heated cantilever and tip

The molecular canvas is a plastic whose surface contains active chemical sites which are initially protected from chemical reaction by capping them with protecting molecules. The heat of the cantilever triggers a confined nanoscale chemical reaction, in which more heat produces a greater local concentration of new surface molecules.

TCNL image of Ansel Adams' Rose and Driftwood, illustrating how the heated cantilever and tip render the image
TCNL image of Ansel Adams' Rose and Driftwood, illustrating how the heated cantilever and tip render the image

More heat produced the lighter shades of gray, as seen on the Mini Lisa’s forehead and hands. Less heat produced the darker shades in her dress and hair seen when the molecular canvas is visualized using fluorescent dye. Each pixel is spaced by 125 nanometers, and the overall image has 240 x 320 pixels.

On the left appears a grey scale image of the real Mona Lisa, while on the right appears an image showing the variations in heat required to create Mini Lisa
On the left appears a grey scale image of the real Mona Lisa, while on the right appears an image showing the variations in heat required to create Mini Lisa

“By tuning the temperature, our team manipulated chemical reactions to yield variations in the molecular concentrations on the nanoscale,” said Jennifer Curtis, an associate professor in the School of Physics and the study’s lead author. “The spatial confinement of these reactions provides the precision required to generate complex chemical images like the Mini Lisa.”

Generating chemical concentration gradients and variations on the sub-micrometer scale is difficult to achieve with other methods. At present the Georgia Tech TCNL system is limited to production of chemical gradients of amine and carboxyl groups, but it is expected that other material chemistries will be compatible with the new process.

“We envision TCNL will be capable of patterning gradients of other physical or chemical properties, such as conductivity of graphene,” Curtis said. “This technique should enable a wide range of previously inaccessible experiments and applications in fields as diverse as nanoelectronics, optoelectronics and bioengineering.”

This simple technique renders high spatial resolutions at a speed faster than other existing methods. While one obvious area of application is in making specialized surfaces for "lab on a chip" development, Professor Curtis is hopeful that TCNL will provide the option of nanoscale printing integrated with the fabrication of large quantities of surfaces or everyday materials whose dimensions are more than one billion times larger than the TCNL features themselves. These would indeed by smart materials.

Source: The Georgia Institute of Technology

View gallery - 6 images
1 comment
The Skud
As a demonstration, this is clever, but how far away are we from practical uses that will assist us, the long-suffering and usually (taxes) grant-paying public?