Multimaterial fibre 'ink' for 3D-printed devices

The system makes use of conventional 3D printers outfitted with a special nozzle and a new kind of filament to replace the usual single-material polymer filament, which typically gets fully melted before it’s extruded from the printer’s nozzle. The researchers’ new filament has a complex internal structure made up of different materials arranged in a precise configuration, and is surrounded by polymer cladding on the outside.

In the new printer, the nozzle operates at a lower temperature and pulls the filament through faster conventional printers do, so that only its outer layer gets partially molten. The interior stays cool and solid, with its embedded electronic functions unaffected. In this way, the surface is melted just enough to make it adhere solidly to adjacent filaments during the printing process, to produce a sturdy 3D structure.

The internal components in the filament include metal wires that serve as conductors, semiconductors that can be used to control active functions, and polymer insulators to prevent wires from contacting each other.