SHEETS of gold one nano-particle thick have been folded into tiny origami. Dubbed plasmene, the material has some of the weirdest optical properties around. It could someday enable things like invisibility cloaks and super-efficient solar cells.
Plasmonic materials, such as gold and silver, capture light and transmit it along their surfaces as waves of electrons called plasmons. They can squeeze light into spaces smaller than the laws of physics normally allow.
That makes them tempting materials for use in antennas to pick up light signals, and possibly someday Harry Potter-style invisibility cloaks. But to be useful, they need to be manipulated into the right shape – and building nanoscale shapes out of gold or silver has so far been impossible.
Wenlong Cheng at Monash University in Melbourne, Australia, and his colleagues made the thin material by coating nanocubes of gold and silver in polystyrene, suspending them in a chloroform solution then spreading it over a fine mesh. Chen called the substance plasmene after the famous carbon-based graphene (ACS Nano, doi.org/wmf).
Using the same technology that etches lines into semiconductors to make computer chips, Chen was able to fold the material into almost any shape, including an origami bird.
"That amazed me," says Michael Cortie at the University of Technology Sydney in Australia. The bendy material may also find uses in medical materials and wearable technology.
This article appeared in print under the headline "Gold origami exerts strange power over light"
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