Flowers grow to face the sun, but flower-like lenses that self-assemble from liquid crystals could offer better ways to capture sunlight.
These liquid crystals are made up of tiny, rod-like molecules that can guide the passage of light. Controlling the direction in which the rods point changes the way they steer light, which sometimes lets them act as lenses.
Previously, researchers had realised that tweaking the way the rods arrange themselves on a surface could help grow lenses much smaller than ones that can be made with glass. But most lenses made this way have needed precisely ordered scaffolds on which to grow.
Now Randall Kamien and his colleagues at the University of Pennsylvania in Philadelphia have found a simpler way: dropping a transparent silicon bead into the solution.
The team found that the liquid crystal layers rearranged themselves around the bead, without the need for a complex frame. "It's like an oyster, which lays down layers of nacre around a grain of sand to form a pearl," says Kamien.
The crystals form a bulge ringed with "petals" that focus light from many directions at once, like the elements of a fly's compound eye, says Kamien. The flower-like bulge also works as a lens, so could one day find uses in solar panels and tiny cameras used in surgery, he adds.
Oleg Lavrentovich at Kent State University in Ohio thinks any potential use for the lens is a long way off. "This is a piece of fundamental physics," he says. "It might result in a lens, it might result in a microrobot, it might result in a trap for microbes. No one is sure at the moment what exactly this research result is good for, but it is definitely good for everything that involves soft matter."
Journal reference: Physical Review X, DOI: 10.1103/PhysRevX.3.041026
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