Illustration of a fibre array taped together, and the cicada, whose wing inspired the invention of the cheap and easy fibre mould.
Credit: Platform Technologies Research Institute, RMIT.
SYDNEY: Inspired by the humble cicada, Australian scientists have shown for the first time that optical fibre nanosensors - tiny devices that can be used to detect trace amounts of chemicals - can be mass-produced.
While many groups around the world are working on increasing the sensitivity of nanosensors, which generally become more effective when used together, this is the first demonstration that they could be manufactured en masse on the tips of optical fibres and could one day be cheap enough to be used across a range of industries.
“We have demonstrated that imprinting nanosensors on optical fibre tips can effectively be done very simply and cheaply,” said lead author Gorgi Kostovski of the Platform Technologies Research Institute and now working with the Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) at RMIT in Melbourne.
Cheap and easy nanosensors
There are a variety of ways to create nanosensors – devices featuring structures one billionth of a metre in size that have the potential to detect in the blood stream molecules such as glucose, and potentially even signs of cancer – and many research groups create them from scratch using electron or ion beams.
But the one thing that all research groups have in common, according to Kostovski, is that they have been making only one optical fibre nanosensor at a time.
However, this Melbourne team, which also involves Arnan Mitchell from RMIT and Paul Stoddart from Swinburne University of Technology, have now managed to create 40 of these nanosensors in just two hours using a cheap and easy to upscale technique known as nanoimprint lithography – which involves creating a mould of a nanostructure and then ‘stamping’ this on to the tips of optical fibres.
Nature’s done the hard work
Instead of making a new template, Kostovski and his team decided to use the clear wing of a cicada - which previous research had shown is covered in a criss-cross of nanostructures that make it less visible to predators.
“In general it’s very difficult to make things on the nanoscale because they’re so small – so cicada wings are convenient because nature has already done the hard work for us ... and they’re very cheap,” said Kostovski of the research which was featured on the cover of Advanced Materials on 25 January 2011.
After the mould has been created, up to 40 optical fibres with flat tips are placed into a unique structure, created by the RMIT team, which has micro-sized u-shaped grooves to hold them in place. The tips are then coated in a soft polymer and pushed against the cicada wing mould, transferring nanostructures to each of the tips.
