The wings of noisy cicada insects have been harnessed as nanoscale printing blocks. Chinese scientists say the synthetic wings could someday be used to make anti-reflective lens coatings and improved laser microscopes.
Cicada鈥檚 wings are covered with thousands of pillar-like protrusions. Each is 400 nanometres tall and tapers from 150 nm wide at the base to 80 nm at the tip.
Jin Zhang and colleagues at Beijing National Laboratory for Molecular Sciences and another team from Capital Normal University, both in China, captured wild cicadas for study. They removed the wings and treated them to remove stains that clog the pillars together. Finally, they tested them as tiny printing blocks.
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The technique, called 鈥渘anoimprint lithography鈥�, involved pressing a wing into a layer of heated plastic to create an imprint, making a mould of the nanoscopic pattern found on each wing.
Acid etching
The mould can be used to make copies of the nanopillar pattern from other materials, including metals and silicon. Such structures could have useful applications, says Zhang. 鈥淭he silicon copy can be used as an anti-reflective layer for optical lenses,鈥� by scattering light that would otherwise cause reflections, he told New 杏吧原创.
Nanopillars made from gold could perhaps improve the sensitivity of Raman spectroscopy probes, he adds. They could aid the scattering of laser light that lets these probes peer inside materials (see Nanotech spy eyes life inside the cell.
The wings make ideal stamps partly because they refuse to stick to the plastic mould. 鈥淲e found that on the surface of the wings there is a layer of wax which acts as an anti-adhesive layer,鈥� explains Zhang.
Lotus leaf
The team plans to try using other natural surfaces for printing. The lotus leaf, which is covered with microscopic water-repelling bumps, is next in line.
Mark Morrison, a nanotechnology expert at the UK鈥檚 Institute of Nanotechnology, says nanoimprint lithography has the potential to scale up for mass production more readily than other more complex nano-fabrication methods.
Currently, he notes, a nano printing template must be created using more complicated processes: 鈥淯sing a natural structure like a cicada wing could be a way to get around that.鈥�
But Morrison also warns that natural templates are not always perfect: 鈥淭hey might not be good at covering large areas,鈥� he says. 鈥淓ven small areas of cicadas鈥� wings have inconsistencies in the pattern.鈥�
Journal reference: Small (vol 2006 2, p 1440)
