Wood could provide a plentiful source material for printing assorted miniature devices, such as an array of lenses for high-resolution projectors.
A technique called ‘nanoimprinting’ can press nanometre-scale patterns into plastic. Now Mingwei Zhu at Nanjing University in China, Liangbing Hu at the University of Maryland in College Park and their colleagues have applied the technique to cellulose in wood fibre, which can serve as an abundant substitute for plastic.
The researchers first stripped wood fibres of their lignin, the natural glue that holds them together. The team then pressed the fibres into a mould with a desired pattern, such as a grid of dots with a diameter of roughly 40 to 90 nanometres.
The authors demonstrated their technique by printing a grid of convex lenses onto a sheet of wood. Each lens is about 6.5 micrometres in diameter — small enough for light to pass through the wood just as it does through a similar lens made of polystyrene, a common plastic. But the wood lens can operate at 150 °C, whereas the plastic lens would melt.