High-tech shrink art could hold the key to creating tiny electronics, 3D nanostructures and even holograms to hide secret messages.
A new method for making tiny structures relies on Minify them after building themrather than making them start getting smaller, researchers report Dec. 23 science.
keys are spongy hydrogel material expand or contract in response to surrounding chemicals (Serial Number: 1/20/10). By engraving patterns in hydrogel with a laser and then shrinking the gel to about a tenth of its original size, the researchers created patterns with details as small as 25 billionths of a meter.
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With this level of precision, the researchers can create letters small enough to easily write entire texts along the circumference of a typical human hair.
Biologist Yongxin Zhao and colleagues deposited a variety of materials in patterns to create nanoscale images of Chinese zodiac animals. By shrinking the hydrogel after laser etching, some of the images ended up being about the size of a red blood cell. They include a monkey made of silver, a gold and silver alloy pig, a titanium dioxide snake, an iron oxide dog and a rabbit made of light-emitting nanoparticles.
Because the hydrogel can repeatedly shrink and expand through a chemical bath, the researchers were also able to create layered holograms within a bulk of the hydrogel to encode secret messages. Shrunk down the hydrogel hologram to make it unreadable. “If you want to read it, you have to expand the sample,” said Zhao of Carnegie Mellon University in Pittsburgh. “But you need to expand it to the exact same extent as the original”. In fact, knowing how well a hydrogel swells is the key to unlocking the information hidden within.
But the most exciting aspect of the research, Zhao said, is the wide range of materials researchers can work with at such tiny scales. “We will be able to combine different types of materials to create truly functional nanodevices.”