Scientists from the Massachusetts Institute of technology have found a way to pattern hundreds-of-metres-long multimaterial fibres with embedded functional elements. Multimaterial fibres that integrate metal, glass and semiconductors will be useful in biomedicine, smart textiles and robotics. But, positioning functional elements has been difficult.

The research has been reported in ACS Central Science. With this method, functional elements, such as electrodes or sensors, could be positioned at specific locations.

Youngbin Lee, Polina Anikeeva and colleagues developed a thiol-epoxy/thiol-ene polymer that could be combined with other materials, heated and drawn from a macroscale model into fibres that were coated with the polymer. When exposed to ultraviolet light, the polymer, which is photosensitive, crosslinked into a network that was insoluble to common solvents, such as acetone. By placing "masks" at specific locations along the fibre in a process known as photolithography, the researchers could protect the underlying areas from UV light. Then, they removed the masks and treated the fibre with acetone. The polymer in the areas that had been covered dissolved to expose the underlying materials.

As a proof of concept, the researchers made patterns along fibres that exposed an electrically conducting filament underneath the thiol-epoxy/thiol-ene coating. The remaining polymer acted as an insulator along the length of the fibre. In this way, electrodes or other microdevices could be placed in customisable patterns along multimaterial fibres, the researchers say.

The authors acknowledge funding from the National Science Foundation, the National Institute of Neurological Disorders and Stroke, and the Kwanjeong Educational Foundation.