A machine that combines multiple 3D printing methods could one day produce prosthetic limbs.Credit: Jae C. Hong/AP/REX/Shutterstock

A prototype 3D printer has for the first time combined several printing methods to enable researchers to produce devices out of multiple materials in a single print run. So far the machine has created basic electronic devices, but the technology brings materials scientists a step closer to their goal of printing complex equipment such as robots or smartphones.

The printer is being presented at a meeting of the American Chemical Society in New Orleans, Louisiana, on 21 March.

“This is a remarkable technological advance and a great leap for the field of 3D printing,” says Xuanhe Zhao, a materials scientist at the Massachusetts Institute of Technology in Cambridge, who was not involved in the work.

The most common 3D printers heat a plastic filament and lay it down in repeated lines, building a layered structure from the bottom up. This is the technique used in inexpensive consumer models. Several other 3D-printing methods have also emerged in recent years, including spraying fine streams of aerosols, printing with liquid resin that is then cured to form a flexible polymer, laying down thin layers of ink that are dried and hardened when exposed to light, and even printing ink that contains conductive nanoparticles, to produce wires and circuits.

“Each printing technology has its own limitations,” says Jerry Qi, a materials scientist at the Georgia Institute of Technology in Atlanta, who led the design of the multimaterial printer. “We put four 3D-printing technologies under one platform.”

Combined forces

Although current 3D printers can already produce electronic parts and devices made of multiple materials, if a structure requires more than one printing method, a different machine is required for each. But moving an object from one printer to another is usually impractical for the micrometre-level precision that is required in 3D printing, and is inefficient if multiple materials are used in a single layer, says Qi.

His team’s multimaterial printer has printheads — the nozzles that produce the material — for each of the four techniques on a single printing platform. Each has its own software, lights for curing the materials, and a moving platform and robot arms that can pick up and place components. This allows the printheads to work together to build single layers with multiple materials. “It is a very smart solution to this challenge,” says Zhou.

Qi and his colleagues have used the printer to embed a light-emitting diode inside a plastic case, printing the inner circuitry at the same time as the outer enclosure. They have also printed a layer of conductive ink inside a rubbery material that can stretch and flex while delivering a current, demonstrating its possibilities for flexible electronics.

A wheel (left) and a flexible conductive ribbon created with a new 3D printer.Credit: Craig Hamel and Conner Dunn

The printer has excited researchers in the field. “We just had a conversation where we were dreaming of that kind of machine,” says Geoff Spinks, a materials engineer at the University of Wollongong in Australia. Such stretchable electronics could be used in compact soft robots, because they offer flexibility that is impossible using the current process of embedding wires into a device, he says.

The machine was mostly funded by the US Air Force and cost roughly US$350,000 to build, says Qi. He thinks the printer’s first customers will be aerospace companies that will use it to design circuitry for avionics, where the ability to print antennas directly could enable rapid prototyping of avionic devices. Qi estimates the printer would sell for about $1 million.

Spinks says this is only the beginning for multimaterial printers. He expects devices with expanded capabilities will soon become available: “I’d imagine in the near future we might have 16 different types of printheads, or even more.”