Nanometric imprinting on fibre

 

Switzerland-based researchers from EPFL's Laboratory of Photonic Materials and Fibre Devices have devised a simple and innovative thermal drawing method to imprint complex, nanometric patterns on hollow polymer fibres. 

 

According to the researchers, imprinted designs could, for example, be used to impart optical effects on a fibre or guide stem-cell growth.

 

To make the nanometric imprints, the researchers first fabricated optical fibres using conventional thermal drawing, in which millimetre-sized patterns are engraved on a macroscopic version of the target fibre, the preform.

 

The imprinted preform is heated to change its viscosity, stretched like molten plastic into a long, thin fiber and then allowed to harden again.

 

Stretching causes the pattern to shrink while maintaining its proportions and position, but as Professor Fabian Sorin, Head of the Photonic Materials and Fibre Devices Laboratory, highlights: “When the fibre is stretched, the surface tension of the structured polymer causes the pattern to deform and even disappear below a certain size, around several microns.”

 

To avoid this problem, the researchers sandwiched the imprinted preform in a sacrificial polymer, which protects the pattern during stretching by reducing the surface tension, and is discarded once stretching is complete.

 

 

In this way, the researchers can apply nanoscale and highly complex patterns to various types of fibres, marking the first time that such minute, complex patterns have been imprinted on flexible fibre on a large scale. 

 

“We have achieved 300 nm patterns, but we could easily make them as small as several tens of nanometres,” highlights Sorin. “This technique enables us to achieve textures with feature sizes two order of magnitude smaller than previously reported, and could be applied to kilometres of fibres at a highly reasonable cost.”

 

Working in vitro with neuroprosthetic technology researchers, including Stéphanie Lacour, the researchers have used the fibres to guide neurites from a spinal ganglion, on the spinal nerve.

 

 

Sorin says this is an encouraging step toward using these fibres to help nerves regenerate or to create artificial tissue. And the development could have implications in many other fields besides biology.

 

“Fibres that are rendered water-resistant by the pattern could be used to make clothes. Or we could give the fibres special optical effects for design or detection purposes," says Sorin. "There is also much to be done with the many new microfluidic systems out there."

 

The researchers now intend to study in vivo nerve regeneration, using the imprinted polymer fibres.

 

Research is published in Advanced Functional Materials.