A new method uses standard 3D printers to produce functioning devices with the electronics already embedded inside. The devices are made of fibers containing multiple interconnected materials that can light up, sense their surroundings, store energy, or perform other actions.
The system uses conventional 3D printers outfitted with a special nozzle and a new filament to replace the usual single-material polymer filament, which typically gets fully melted before it is extruded from the printer's nozzle. The 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 than 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. As a demonstration, the team printed a wing for a model airplane using filaments that contained both light-emitting and light-detecting electronics. These components could potentially reveal the formation of any microscopic cracks that might develop. While the filaments used in the model wing contained eight different materials, in principle they could contain even more.
The method makes use of thermally drawn fibers that contain a variety of different materials embedded within them. Researchers have created an array of fibers that have electronic components within them, enabling the fibers to carry out a variety of functions; for example, for communications applications, flashing lights can transmit data that is then picked up by other fibers containing light sensors.
To make the fibers, the different materials are assembled into a larger-scale version called a preform, which is then heated and drawn in a furnace to produce a very narrow fiber that contains all those materials, in their same relative positions but greatly reduced in size.
The method could potentially be developed further to produce a variety of different kinds of devices, especially for applications where the ability to precisely customize each device is essential. One such area is for biomedical devices, where matching the device to the patient's own body can be important. Prosthetic limbs might someday be printed using this method, not only matching the precise dimensions and contours of the patient's limb, but with all the electronics to monitor and control the limb embedded in place.